Winamp m3u/pls .WMA Extension Buffer Overflow Vulnerability

iDefense Security Advisory 02.01.06
http://www.idefense.com/intelligence/vulnerabilities/display.php?id=378
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 with a
target filename having the .wma extension can crash Winamp giving the
attacker control over the EAX register.

Example m3U file format:

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

Example pls file format:

[playlist]
numberofentries=5
File1=AAAA[...]AA.wma
Title1=
Length5=-1
Version=2

III. ANALYSIS

When Winamp is installed it registers the m3u and pls extensions so that
such files  will automatically open in Winamp. This exploit can be
triggered by clicking on a link in a web page, or through the use of
malicious javascript.

The crash occurs in the Winamp module with the following instructions:

mov edx, [eax]
call [edx+24]

The number of characters that can be inject is limited. With control
of the EAX register injected into the above code, meaningful
shellcode execution is possible.

IV. DETECTION

This vulnerability has been verified in version 5.094 of Winamp.

V. WORKAROUND

Removing the file mapping for m3u and pls files to Winamp should
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 5.11.
Version 5.13 is now available for download at:

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

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2005-3188 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

10/12/2005 Initial vendor notification
02/01/2006 Coordinated public disclosure

IX. CREDIT

This vulnerability was discovered by b0f.

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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
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or consequential loss or damage arising from use of, or reliance on,
this information.