Sophos Anti-Virus Petite File Denial of Service Vulnerability
iDefense Security Advisory 10.31.06
Oct 31, 2006
Sophos Anti-Virus is comprehensive scanning solution used to protect
users from viruses, malicious code, ad-ware, trojans, and more. For more
information see their website at http://sophos.com/
Remote exploitation of a denial of service vulnerability in version 5.1
of Sophos Anti-Virus could result in unusable system conditions.
The problem manifests itself when the scanning engine encounters an
executable compressed with petite that contains a large number of
Successful exploitation would result in the scanning engine attempting
to allocate an extremely large amount of memory resulting in memory
exhaustion on the system in question. The auto-scan features of Sophos
Anti-Virus will attempt to scan files on access.
iDefense has confirmed the existence of this issue with Sophos Anti-Virus
5.1 for Windows as well as version 5 for Linux. It is suspected that
earlier versions and other architectures are also vulnerable.
iDefense is unaware for any effective workarounds for this issue.
VI. VENDOR RESPONSE
Sophos recommends upgrading to an unaffected version of the scan engine.
For more information consult the following support article.
VII. CVE INFORMATION
The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2006-4839 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
VIII. DISCLOSURE TIMELINE
09/15/2006 Initial vendor notification
09/19/2006 Initial vendor response
10/31/2006 Coordinated public disclosure
This vulnerability was reported to iDefense by Damian Put