Multiple Vendor FLAC Library Multiple Integer Overflow Vulnerabilities

iDefense Security Advisory 10.11.07
http://labs.idefense.com/intelligence/vulnerabilities/
Oct 11, 2007

I. BACKGROUND

Free Lossless Audio Codec (FLAC) is a popular file format for audio data
compression. AOL Corp.'s Winamp media player has support for the FLAC
format. More information about FLAC and Winamp is available at the
following URLs.

http://flac.sourceforge.net/
http://www.winamp.com/

II. DESCRIPTION

Remote exploitation of multiple integer overflow vulnerabilities in
libFLAC, as included with various vendor's software distributions,
allows attackers to execute arbitrary code in the context of the
currently logged in user.

These vulnerabilities specifically exist in the handling of malformed
FLAC media files. In each case, an integer overflow can occur while
calculating the amount of memory to allocate. As such, insufficient
memory is allocated for the data that is subsequently read in from the
file, and a heap based buffer overflow occurs.

III. ANALYSIS

Exploitation allows remote attackers to execute arbitrary code in the
context of the user attempting to play the media file. Exploitation
requires that an attacker persuade a targeted user into opening a
malformed FLAC file.

IV. DETECTION

iDefense has confirmed the existence of these vulnerabilities libFLAC
1.2.0, as well as the version of libFLAC included in in the full 5.35
version Winamp. Previous versions of libFLAC may also be vulnerable.
The lite version of Winamp does not include support for the FLAC file
format, and as such is not vulnerable.

V. WORKAROUND

For Winamp users, it is possible to remove support for the FLAC file
format by uninstalling the FLAC input plug-in.

VI. VENDOR RESPONSE

The FLAC maintainers have released version 1.2.1 of FLAC to address
these vulnerabilities. AOL Corp. has addressed this vulnerability in
version 5.5 of Winamp. For more information see the FLAC change log at
the following URL.

http://flac.sourceforge.net/changelog.html

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2007-4619 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

08/29/2007  Initial vendor notification
08/29/2007  Initial vendor response
10/11/2007  Coordinated public disclosure

IX. CREDIT

This vulnerability was reported to iDefense by Sean de Regge.

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X. LEGAL NOTICES

Copyright © 2007 iDefense, Inc.

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