Winamp m3u Parsing Stack Overflow Vulnerability

iDefense Security Advisory 02.01.06
http://www.idefense.com/intelligence/vulnerabilities/display.php?id=377
February 1, 2006

I. BACKGROUND

Winamp is a popular media player for Windows which supports many
audio/video file formats.

More information can be obtained from the vendors site at:

 http://winamp.com/player/

II. DESCRIPTION

It has been found that a specially crafted m3u or pls file can overwrite
a stack based buffer allowing for remote code execution.

Example m3U file format:

#EXTM3U
#EXTINF:,VULN
AAAA[...]AA

Example pls file to trigger exploit:

[playlist]
numberofentries=1
File1=\\01 01AAA[...]AAA

This vulnerability is specific to the 5.11 version of Winamp and does
not affect previous versions.

III. ANALYSIS

When Winamp is installed it registers the m3u extension so that such
files  will automatically open in Winamp. This exploit can be triggered
by  clicking on a link in a webpage, or from the use of malicious
javascript.

Exploitation is straight forward, using a long full path. This path
can be either a filename or the UNC name for a fileshare, which does
not have to exist.

Public exploit code has been independently released for this
vulnerability (http://www.spyinstructors.com).

IV. DETECTION

This exploit was tested with version 5.11 of Winamp. Previous versions
were tested and found to not be exploitable.

V. WORKAROUND

Removing the file associations for the m3u and pls file extension may
mitigate the risk of exploitation.

VI. VENDOR RESPONSE

The vendor has not responded to communication regarding this
vulnerability.

The vulnerability appears to have been silently fixed in Winamp 5.13
which is available for download at:

  http://www.winamp.com/player/

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2006-0476 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
security problems.

VIII. DISCLOSURE TIMELINE

12/15/2005 Initial vendor notification
02/01/2006 Public disclosure

IX. CREDIT

This vulnerability was independently discovered by Alan Mccaig (b0f)
b0fnet@yahoo.com and Ruben Santamarta (ruben@reversemode.com).

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X. LEGAL NOTICES

Copyright (c) 2006 iDefense, Inc.

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Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
of the information constitutes acceptance for use in an AS IS condition.
There are no warranties with regard to this information. Neither the
author nor the publisher accepts any liability for any direct, indirect,
or consequential loss or damage arising from use of, or reliance on,
this information.