Man ... those voices in my head... they keep screaming "DMCA"! -KF
[EMAIL PROTECTED] 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
_______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.netsys.com/full-disclosure-charter.html
