Somebody once said..

"If you convince people that the wheel isn't right, they will allow you to re-invent it"

Friday, March 12, 2010

CVE-2010-0188 Adobe Reader TIFF vulnerability

The recent Adobe reader vulnerability (CVE-2010-0188) seems to be doing lot of rounds these days. Thanks to Mila (contagio blog), I got a chance to look at the malicious PDF file.

A Quick look at the stats using pdf-parser tool reveals the structure of this file -

C:\Analyze> -a "2010 March Luncheon Invitation_FINAL.pdf"
Comment: 4
Trailer: 0
StartXref: 2
Indirect object: 43
12: 44, 45, 46, 55, 91, 92, 112, 114, 115, 117, 115, 135
/Catalog 1: 43
/EmbeddedFile 9: 2, 3, 5, 6, 7, 121, 122, 123, 124
/Filespec 2: 116, 134
/Metadata 2: 13, 13
/ObjStm 9: 125, 126, 127, 128, 129, 130, 131, 132, 136
/XObject 6: 56, 57, 113, 118, 119, 120
/XRef 2: 133, 137

Since most of the PDF exploits are created using embedded JavaScript, my instinct was to look for JavaScript object streams inside the PDF. But that didn’t reveal any interesting results, so I turned my attention to other objects.

The actual shellcode appears to be present in object 119 -


..while the TIFF file in object 122 is used to cause the overflow in the ImageConversion.api -


Finally object 3 contains the reference to TIFF file -


All the streams in the PDF file are compressed, so I had to use the “-f” option with pdf-parser tool to inflate them and see the content. There was also a wave file stream in the PDF which is a little strange, but I could not get it to play !

Both the dropped files appear to be the same as explained in Mila’s previous analysis on the Contagio blog. Lastly, the PDF seems to have been created on 25-Feb-2010 and modified on 03-Mar-2010 using Adobe LiveCycle Designer ES 8.2.

After reading some more on the exploit, I found that the exploit for this vulnerability does not use JavaScript. Which means even if you have disabled JavaScript in Adobe reader, this exploit will work and that probably explains why bad guys are going after this vulnerability despite Adobe releasing the patches last month !

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