RE: security in yahoo messenger - anwar azam khan

Here is the article from Internet Storm Center where I got my information:

http://isc.sans.org/diary.html?storyid=2952


Yahoo! Messenger exploits seen in the wild
Published: 2007-06-10,
Last Updated: 2007-06-10 01:42:13 UTC
by Bojan Zdrnja (Version: 1)
Just three days after the PoCs for 2 Yahoo! Messenger vulnerabilities have
been posted (http://isc.sans.org/diary.html?storyid=2943), we've been
informed by Roger C. from the Malware-Test Lab about a site hosting exploits
for the mentioned vulnerabilities.

The exploit is referenced the standard way - an iframe points to the web
site hosting the exploit (n.88tw.net). The exploit has been pretty simply
obfuscated. One thing that makes it easier to identify is the object
creation - for some reason attackers left it outside of the obfuscated
string so it is very easy to spot:

<object classid="clsid:DCE2F8B1-A520-11D4-8FD0-00D0B7730277"
id='viewme'></object>

Practically the only difference from the published PoC is the objects name -
in this case it is, as you can see above, "viewme", while the object name in
the originally published PoC was "target".

The rest is very much the same, apart from the attached shellcode. The
shellcode in the sample we analyzed downloaded another dropper (of course),
and this second component wasn't detected by any AV vendor on the VirusTotal
site when we tested it (!!). This dropper downloaded further components, of
which one was called 5in1.exe - we haven't analyzed this yet but judging
just by the file name, it doesn't sound good.

Mitigation

As you are probably aware, Yahoo! provided a fix practically only couple of
hours after the PoCs have been posted online (kudos to Yahoo! for this). If
you are using Yahoo! Messenger you should upgrade as soon as possible.
Alternatively, you can set the kill bits for the affected ActiveX controls,
as we've posted in our original diary.

One thing that might help as well is the AV detection. Although the second
stage dropper wasn't detected by any AV vendor, the JavaScript that triggers
the exploit was detected by couple of programs. As the names were generic
(HEUR/Exploit.HTML, JS:Feebs-D, Heuristic.Exploit.HTML), my guess is that
those that detected this properly got lucky (the Javascript used standard
eval(unescape("") method). In any case, every defense layer helps.


Patrick
-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of anwar azam khan
Sent: Friday, June 15, 2007 6:34 AM
To: [email protected]
Subject: security in yahoo messenger - anwar azam khan


hello !
i have listen about the bugs in yahoo messnger? In previous days, there was
alot of problem in securitires of yahoo messenger?

Bela
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