Clam AntiVirus ClamAV CHM Chunk Name Length DoS Vulnerability

iDefense Security Advisory 10.15.06
http://www.idefense.com/intelligence/vulnerabilities/
Oct 15, 2006

I. BACKGROUND

Clam AntiVirus is a multi-platform GPL anti-virus toolkit.  The main
purpose of which is integration into electronic mail servers.  More
information about ClamAV can be found at http://clamav.net/.  Microsoft
Compressed HTML Help (CHM) files are commonly used for windows based
software documentation.

II. DESCRIPTION

Remote exploitation of a input validation vulnerability in Clam
AntiVirus's ClamAV could allow attackers to crash the virus scanning
service.

The vulnerability specifically exists due to improper handling of an
specially crafted CHM file.  While processing such a file, ClamAV may
attempt to read an invalid memory location resulting in abnormal
termination of the scanning service.

III. ANALYSIS

Successful exploitation could allow an attacker to crash the ClamAV
virus scanning service.  Exploitation requires that attackers send a
specially constructed CHM file through an e-mail gateway or personal
anti-virus client using the ClamAV scanning engine.

IV. DETECTION

iDefense has confirmed this vulnerability affects Clam AntiVirus ClamAV
v0.88.4. All prior versions that implement CHM file scanning are
suspected to be vulnerable.

V. WORKAROUND

iDefense is unaware of any effective workarounds for this issue.

VI. VENDOR RESPONSE

The ClamAV team has addressed this vulnerability within version 0.88.5.

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2006-5295 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

09/28/2006  Initial vendor notification
09/29/2006  Initial vendor response
10/10/2006  Second vendor notification
10/15/2006  Coordinated public disclosure

IX. CREDIT

This vulnerability was reported to iDefense by Damian Put and an
anonymous researcher.

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X. LEGAL NOTICES

Copyright © 2006 iDefense, Inc.

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at the time of publishing based on currently available information. Use
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