[NT] AOL Nullsoft Winamp IT Module Heap Memory Corruption (IN_MOD.DLL)

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AOL Nullsoft Winamp IT Module Heap Memory Corruption (IN_MOD.DLL)
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SUMMARY

<http://www.winamp.com/> Winamp is "a proprietary media player written by
Nullsoft, a subsidiary of Time Warner. It is skinnable, multi-format
freeware / shareware". Successful exploitation may allow the attacker to
run arbitrary code in context of user running AOL Nullsoft Winamp.

DETAILS

Vulnerable Systems:
* AOL Nullsoft Winamp version 5.33 (x86) Feb 13 2007 (on Windows XP
SP1/SP2).

The problem takes place when Winamp is trying to play specially crafted
IT file.

IT is the proprietary module format used by Impulse Tracker, featuring
support for more advanced features than MOD or S3M before it. These
include a larger limit for lines in a pattern, higher quality samples, and
other effects.

Take a look a this code snippet:
----// SNIP SNIP //-------------------------------------------------
text:00E97BCA write_looop: ; CODE XREF:
sub_E97976+29D#j
text:00E97BCA mov edx, [ebp+6Ch+arg_0]
text:00E97BCD mov ecx, [ebx+18h]
text:00E97BD0 mov dx, [eax+edx*2]
text:00E97BD4 mov [eax+ecx*2], dx
text:00E97BD8 mov eax, [ebx+370h]
text:00E97BDE mov ecx, [ebx+18h]
text:00E97BE1 mov cx, [eax+ecx*2]
text:00E97BE5 cmp cx, [esi+6Eh]
text:00E97BE9 jnb short loc_E97C09
text:00E97BEB mov al, [ebx+18h]
text:00E97BEE mov ecx, [ebp+6Ch+arg_0]
text:00E97BF1 mov [ecx+esi+148h], al ; BANG
text:00E97BF8 mov eax, [ebx+370h]
text:00E97BFE cmp word ptr [eax+ecx*2], 0FEh
text:00E97C04 jnb short loc_E97C09
text:00E97C06 inc dword ptr [ebx+18h]
text:00E97C09
text:00E97C09 loc_E97C09: ; CODE XREF:
sub_E97976+273#j
text:00E97C09 ; sub_E97976+28E#j
text:00E97C09 movzx ecx, word ptr [esi+68h] ;
ecx=controlled value (from offset 0x20)
text:00E97C0D inc [ebp+6Ch+arg_0]
text:00E97C10 cmp [ebp+6Ch+arg_0], ecx
text:00E97C13 jb short write_looop
----// SNIP SNIP //-------------------------------------------------

The memory is overwritten at 0x00E97BF1. The description of this
disassembly listing is pretty similar to the one written in s3m module
files advisory.


ADDITIONAL INFORMATION

The information has been provided by <mailto:bania.piotr@xxxxxxxxx> Piotr
Bania.
The original article can be found at:

<http://www.piotrbania.com/all/adv/nullsoft-winamp-it_module-in_mod-adv.txt> http://www.piotrbania.com/all/adv/nullsoft-winamp-it_module-in_mod-adv.txt



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