macOS XNU - Copy-on-Write Behaviour Bypass via Partial-Page Truncation of File

macOS XNU - Copy-on-Write Behaviour Bypass via Partial-Page Truncation of File / XNU has various interfaces that permit creating copy-on-write copies of data between processes, including out-of-line message descriptors in mach messages. It is important that the copied memory is protected against...

macOS < 10.14.3 / iOS < 12.1.3 XNU - 'vm_map_copy' Optimization which Requires Atomicity isn't Atomic

/ vmmapcopyininternal in vmmap.c converts a region of a vmmap into "copied in" form, constructing a vmmapcopy structure representing the copied memory which can then be mapped into another vmmap or the same one. The function contains a while loop which walks through each of the vmmapentry...

macOS XNU - Copy-on-Write Behaviour Bypass via Partial-Page Truncation of File

/ XNU has various interfaces that permit creating copy-on-write copies of data between processes, including out-of-line message descriptors in mach messages. It is important that the copied memory is protected against later modifications by the source process; otherwise, the source process might ...

voucher_swap: Exploiting MIG reference counting in iOS 12

Posted by Brandon Azad, Project Zero In this post I'll describe how I discovered and exploited CVE-2019-6225, a MIG reference counting vulnerability in XNU's taskswapmachvoucher function. We'll see how to exploit this bug on iOS 12.1.2 to build a fake kernel task port, giving us the ability to re...

XNU - POSIX Shared Memory Mappings have Incorrect Maximum Protection

XNU - POSIX Shared Memory Mappings have Incorrect Maximum Protection When the mmap syscall is invoked on a POSIX shared memory segment DTYPEPSXSHM, pshmmmap maps the shared memory segment's pages into the address space of the calling process. It does this with the following code: int prot =...

XNU POSIX Shared Memory Mapping Issue

XNU: POSIX shared memory mappings have incorrect maximum protection CVE-2018-4435 When the mmap syscall is invoked on a POSIX shared memory segment DTYPEPSXSHM, pshmmmap maps the shared memory segment's pages into the address space of the calling process. It does this with the following code: int...

XNU POSIX Shared Memory Mapping Issue Exploit

Exploit for multiple platform in category local exploits XNU: POSIX shared memory mappings have incorrect maximum protection CVE-2018-4435 When the mmap syscall is invoked on a POSIX shared memory segment DTYPEPSXSHM, pshmmmap maps the shared memory segment's pages into the address space of the...

XNU - POSIX Shared Memory Mappings have Incorrect Maximum Protection

When the mmap syscall is invoked on a POSIX shared memory segment DTYPEPSXSHM, pshmmmap maps the shared memory segment's pages into the address space of the calling process. It does this with the following code: int prot = uap-prot; ... if prot & PROTWRITE && fp-fflag & FWRITE == 0 returnEPERM;...

XNU Kernel iOS / macOS heap buffer overflow Exploit

The vulnerability is a heap buffer overflow in the networking code in the XNU operating system kernel. XNU is used by both iOS and macOS, which is why iPhones, iPads, and Macbooks are all affected. My exploit PoC just overwrites the heap with garbage, which causes an immediate kernel crash and...

Apple iOS/macOS - Sandbox Escape due to mach Message sent from Shared Memory

iohideventsystem sets up a shared memory event queue; at the end of this shared memory buffer it puts a mach message which it sends whenever it wants to notify a client that there's data available in the queue. As a client we can modify this mach message such that the server hidd on MacOS,...

XNU kernel heap overflow due to bad bounds checking in MPTCP(CVE-2018-4241)

mptcpusrconnectx is the handler for the connectx syscall for the APMULTIPATH socket family. The logic of this function fails to correctly handle source and destination sockaddrs which aren't AFINET or AFINET6: // verify salen for AFINET: if dst-safamily == AFINET && dst-salen !=...

XNU Kernel - Heap Overflow Due to Bad Bounds Checking in MPTCP

mptcpusrconnectx is the handler for the connectx syscall for the APMULTIPATH socket family. The logic of this function fails to correctly handle source and destination sockaddrs which aren't AFINET or AFINET6: // verify salen for AFINET: if dst-safamily == AFINET && dst-salen !=...

XNU Kernel - Heap Overflow Due to Bad Bounds Checking in MPTCP Exploit

Exploit for multiple platform in category dos / poc mptcpusrconnectx is the handler for the connectx syscall for the APMULTIPATH socket family. The logic of this function fails to correctly handle source and destination sockaddrs which aren't AFINET or AFINET6: // verify salen for AFINET: if...

XNU Kernel - Heap Overflow Due to Bad Bounds Checking in MPTCP

XNU Kernel - Heap Overflow Due to Bad Bounds Checking in MPTCP mptcpusrconnectx is the handler for the connectx syscall for the APMULTIPATH socket family. The logic of this function fails to correctly handle source and destination sockaddrs which aren't AFINET or AFINET6: // verify salen for...

Apple macOS HighSierra 10.13 - ctl_ctloutput-leak Information Leak Exploit

Exploit for macOS platform in category local exploits / ctlctloutput-leak.c Brandon Azad CVE-2017-13868 While looking through the source code of XNU version 4570.1.46, I noticed that the function ctlctloutput in the file bsd/kern/kerncontrol.c does not check the return value of sooptcopyin, which...

Apple macOS XNU Kernel - Memory Disclosure due to bug in Kernel API for Detecting Kernel Memory Disclosures

/ Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1372 the kernel libproc API proclistuptrs has the following comment in it's userspace header: / Enumerate potential userspace pointers embedded in kernel data structures. Currently inspects kqueues only. NOTE: returned "pointers"...

Apple macOS XNU Kernel - Memory Disclosure due to bug in Kernel API for Detecting Kernel Memory Disclosures

Apple macOS XNU Kernel - Memory Disclosure due to bug in Kernel API for Detecting Kernel Memory Disclosures / Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1372 the kernel libproc API proclistuptrs has the following comment in it's userspace header: / Enumerate potential...

Apple macOS High Sierra 10.13 - ctl_ctloutput-leak Information Leak

Apple macOS High Sierra 10.13 - ctlctloutput-leak Information Leak / ctlctloutput-leak.c Brandon Azad CVE-2017-13868 While looking through the source code of XNU version 4570.1.46, I noticed that the function ctlctloutput in the file bsd/kern/kerncontrol.c does not check the return value of...

Apple MacOS 32-Bit Syscall Exit Kernel Register Leak(CVE-2017-2509)

The XNU kernel, when compiled for a x86-64 CPU, can run 32-bit x86 binaries in compatibility mode. 32-bit binaries use partly separate syscall entry and exit paths. To return to userspace, unixsyscall in bsd/dev/i386/systemcalls.c calls threadexceptionreturn in osfmk/x8664/locore.s, which in turn...

Apple macOS - 32-bit syscall exit Kernel Register Leak Exploit

Exploit for macOS platform in category dos / poc Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1149 The XNU kernel, when compiled for a x86-64 CPU, can run 32-bit x86 binaries in compatibility mode. 32-bit binaries use partly separate syscall entry and exit paths. To return to...