Sophos Antivirus CHM Chunk Name Length Memory Corruption Vulnerability
iDefense Security Advisory 12.08.06
Dec 08, 2006
Sophos AntiVirus offers protection from the latest Trojans, worms and
Viruses. More information is available on the vendors site at:
Sophos AntiVirus Engine is vulnerable to a Memory Corruption vulnerability
when scanning malformed CHM archives.
This memory corruption vulnerability can be triggered when Sophos
Antivirus engine scans a malformed CHM file which has a large name length
specified in a CHM chunk header.
Malformed CHM files can lead to a Memory Corruption condition on the local
machine. This memory corruption vulnerability could potentially result in
arbitrary code execution.
Files received as email attachments, uploaded via web forms or otherwise
saved to disk may trigger this condition if auto scanning is enabled on
the target machine.
Archive scanning is disabled by default and must be specified in order for
this vulnerability to trigger.
iDefense has confirmed this vulnerability in the following Sophos Antivirus
* Sophos Small business edition (Linux)
Product version: 4.06.1
Engine version : 2.34.3
Previous versions of Sophos Antivirus are suspected vulnerable. Other
Sophos Antivirus products may also be vulnerable.
Windows versions of the Sophos Antivirus product do not appear to be
Disabling the option to scan within archives will prevent exploitation of
VI. VENDOR RESPONSE
Sophos has addressed this problem with new versions of their products. See
http://www.sophos.com/support/knowledgebase/article/7609.html for more
VII. CVE INFORMATION
The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2006-5647 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
VIII. DISCLOSURE TIMELINE
09/28/2006 Initial vendor notification
10/02/2006 Initial vendor response
12/08/2006 Coordinated public disclosure
This vulnerability was reported to iDefense by Damian Put