Full Disclosure mailing list archives
Internet Explorer Help System RCE
From: Mike Allen <mallen7474 () yahoo com>
Date: Thu, 12 May 2005 22:15:55 -0700 (PDT)
Hi, quick question on decoding. A little background first. Earlier tonight, one of my co-workers found what might he thinks might be the first "in the wild" example of the Internet Explorer/ms-its protocol vulnerability. (Discussed at gossamer-threads.com/lists/fulldisc/full-disclosure/30100.) The exploit itself is based on a Proof-of-Concept by ShredderSub7. This is another unpatched flaw that has been known since at least December. This particular exploit attempts to download a phony JPEG file from iframedollars.biz/dl/adv622/JQTmudI.jpg (the SubSeven PoC downloads a harmless htm.txt file instead). This not a JPEG, but, rather, is a BASE64-encoded PHP script. There is a decoding script at the end, but I cannot make heads nor tails of what this decodes to. I have very little PHP experience, but it seems to take a character out of an encoded string, subtract that from 127, and then convert it to Unicode. Here is the decoding script: for(i=0;i<568;i++)s=s.substr(1)+String.fromCharCode(127-s.charCodeAt(0));document.write(s); I wrote a small decoder in assembly to perform what I think this thing does, but all I got was the original code. Am I missing something here? Is this really an obfuscation script or am I chasing ghosts? It's be happy to provide the munged data itself, if I can cut 'n' paste it, but I'm basically interested in knowing whether I am even on the right track. Mike __________________________________ Do you Yahoo!? Yahoo! Small Business - Try our new resources site! http://smallbusiness.yahoo.com/resources/ _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.grok.org.uk/full-disclosure-charter.html Hosted and sponsored by Secunia - http://secunia.com/
Current thread:
- Internet Explorer Help System RCE Mike Allen (May 12)
- Re: Internet Explorer Help System RCE Duncan Hill (May 12)