Adobe Flash - Out-of-Bounds Memory Read While Parsing a Mutated '.TTF' File Embedded in SWF

EDB-ID:

37858




Platform:

Windows

Date:

2015-08-19


Become a Certified Penetration Tester

Enroll in Penetration Testing with Kali Linux , the course required to become an Offensive Security Certified Professional (OSCP)

GET CERTIFIED

Source: https://code.google.com/p/google-security-research/issues/detail?id=363&can=1&q=label%3AProduct-Flash%20modified-after%3A2015%2F8%2F17&sort=id

The following access violation was observed in the Adobe Flash Player plugin:

(1ba8.1c60): 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 FlashPlayer.exe - 
eax=0004c800 ebx=00000000 ecx=08982000 edx=00002588 esi=00001200 edi=0042d46c
eip=017723c0 esp=0042d278 ebp=0042d3c4 iopl=0         nv up ei pl nz na pe nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b             efl=00210206
FlashPlayer!IAEModule_IAEKernel_UnloadModule+0x254f0:
017723c0 8b0408          mov     eax,dword ptr [eax+ecx] ds:002b:089ce800=????????

0:000> kb
ChildEBP RetAddr  Args to Child              
WARNING: Stack unwind information not available. Following frames may be wrong.
0042d3c4 0177cfaf 0042d3e0 0042d46c 00000001 FlashPlayer!IAEModule_IAEKernel_UnloadModule+0x254f0
0042d3ec 0177d112 0042d414 0042d46c 00001376 FlashPlayer!IAEModule_IAEKernel_UnloadModule+0x300df
0042d424 0177d4c2 0042d454 0042d46c 00000006 FlashPlayer!IAEModule_IAEKernel_UnloadModule+0x30242
0042d4e0 0176ec7a 00000000 0042d540 03497440 FlashPlayer!IAEModule_IAEKernel_UnloadModule+0x305f2
0042d544 01788715 08875020 47535542 6c61746e FlashPlayer!IAEModule_IAEKernel_UnloadModule+0x21daa
0042d7d8 01775c95 0042d814 01775f31 01775f41 FlashPlayer!IAEModule_IAEKernel_UnloadModule+0x3b845
0042d7e0 01775f31 01775f41 03497440 00000000 FlashPlayer!IAEModule_IAEKernel_UnloadModule+0x28dc5
0042d828 017834d2 03497440 00000000 00000030 FlashPlayer!IAEModule_IAEKernel_UnloadModule+0x29061
00000000 00000000 00000000 00000000 00000000 FlashPlayer!IAEModule_IAEKernel_UnloadModule+0x36602

0:000> db ecx
08982000  35 00 00 00 01 00 00 00-00 00 00 00 00 00 00 ff  5...............
08982010  00 00 00 00 00 00 00 00-01 00 00 00 00 00 00 00  ................
08982020  80 a4 b7 01 00 00 00 00-00 00 00 00 00 10 00 00  ................
08982030  00 00 00 00 18 a8 b7 01-20 50 87 08 00 00 00 00  ........ P......
08982040  03 30 02 00 49 00 00 00-01 00 00 00 00 00 00 00  .0..I...........
08982050  00 00 00 ff 00 00 00 00-00 00 00 00 01 00 00 00  ................
08982060  00 00 00 00 80 a4 b7 01-00 00 00 00 00 00 00 00  ................
08982070  00 10 00 00 00 00 00 00-18 a8 b7 01 20 50 87 08  ............ P..

0:000> !address ecx
[...]
Usage:                  <unknown>
Base Address:           08906000
End Address:            08990000
Region Size:            0008a000
State:                  00001000	MEM_COMMIT
Protect:                00000004	PAGE_READWRITE
Type:                   00020000	MEM_PRIVATE
Allocation Base:        087f0000
Allocation Protect:     00000001	PAGE_NOACCESS

Notes:

- Reliably reproduces with latest Adobe Flash Player Projector for Windows and Google Chrome for Windows.

- The out-of-bounds read appears to be caused by an overly large index value (stored in the "EAX" register at the time of the crash) relative to a dynamically allocated buffer pointed to by "ECX".

- The 32-bit value read from the unmapped memory address is in fact a pointer, and is used to immediately read 12 bytes from in one function up the call chain.

- Attached samples: signal_sigsegv_7ffff710e9d3_881_11431348555663755408.ttf.swf (crashing file), 11431348555663755408.ttf.swf (original file).

Proof of Concept:
https://github.com/offensive-security/exploitdb-bin-sploits/raw/master/bin-sploits/37858.zip