[VulnWatch] uuuppz.com - Advisory 002 - mIRC $asctime overflow

From: James Martin (fulldisclose@uuuppz.com)
Date: 08/27/02


From: "James Martin" <fulldisclose@uuuppz.com>
To: <vulndiscuss@vulnwatch.org>, <vulnwatch@vulnwatch.org>, <vuln-dev@securityfocus.com>, <news@securiteam.com>, "Windows NTBugtraq Mailing List" <NTBUGTRAQ@LISTSERV.NTBUGTRAQ.COM>, <full-disclosure@lists.netsys.com>, <bugtraq@securityfocus.com>
Date: Tue, 27 Aug 2002 14:58:50 +0100


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General Info
- ------------
Researched by: James Martin
Full advisory: http://www.uuuppz.com/research/adv-002-mirc.htm
Exploit: Proof of concept code available at above URL.

Product: mIRC
Website: http://www.mirc.com
Version: V6.00, V6.01, V6.02.
Fix: Download mIRC 6.03 from http://www.mirc.com
     Please do not download from unofficial sites, as you may
download
     a trojaned version.
Type: Buffer Overrun
Risk: Low to High

Summary
- -------
mIRC provides scripting capabilities to allow extension of the
client. A flaw exists in the $asctime identifier, which is used to
format Unix style time stamps. Passing a string of sufficient length
to $asctime will cause a buffer overflow on the stack. This allows
the execution of byte code through calling $asctime with a carefully
constructed string.

The default script included with mIRC does not call $asctime at any
point. However the majority of major scripts available for download
call $asctime to decode data provided by the irc server. Many scripts
call $asctime on data provided from other remote sources. The
exploitation of this flaw therefore depends on the script installed
by the victim.

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