full-disclosure - GAYER THAN AIDS ADVISORY #01: IE 5 remote code execution

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From: dotslash at snosoft.com (KF)
Subject: GAYER THAN AIDS ADVISORY #01: IE 5 remote code
 execution

Btw this does nothing to the IE on Win2k Version: 5.00.3700.1040,
Update Versions: SP4;Q824145:Q832894
-KF

KF wrote:
> Man ... those voices in my head... they keep screaming "DMCA"!
> -KF
> 
> gta@...h.com wrote:
> 
>> I downloaded the Microsoft source code.  Easy enough.  It's a lot
>> bigger than Linux, but there were a lot of people mirroring it and so
>> it didn't take long.
>>
>> Anyway, I took a look, and decided that Microsoft is GAYER THAN AIDS.
>> For example, in win2k/private/inet/mshtml/src/site/download/imgbmp.cxx:
>>
>>     // Before we read the bits, seek to the correct location in the file
>>     while (_bmfh.bfOffBits > (unsigned)cbRead)
>>     {
>>         BYTE abDummy[1024];
>>         int cbSkip;
>>
>>         cbSkip = _bmfh.bfOffBits - cbRead;
>>                 if (cbSkip > 1024)
>>             cbSkip = 1024;
>>
>>         if (!Read(abDummy, cbSkip))
>>             goto Cleanup;
>>                     cbRead += cbSkip;
>>     }
>>
>> .. Rrrrriiiiggghhhttt.  Way to go, using a signed integer for an
>> offset.  Now all we have to do is create a BMP with bfOffBits > 2^31,
>>
>> and we're in. cbSkip goes negative and the Read call clobbers the
>> stack with our data.
>>
>> See attached for proof of concept.  index.html has [img src=1.bmp]
>> where 1.bmp contains bfOffBits=0xEEEEEEEE plus 4k of 0x44332211.
>> Bring it up in IE5 (tested successfully on Win98) and get
>> EIP=0x44332211.
>>
>> IE6 is not vulnerable, so I guess I'll get back to work.  My Warhol
>> worm will have to wait a bit...
>>
>> .gta
>> PROPS TO the Fort and HAVE IT BE YOU.
>>
>>
>>
>> ------------------------------------------------------------------------
>>
>>
>>   Hello
>>
> 
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