I. BACKGROUND

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/

II. DESCRIPTION

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 sections.

III. ANALYSIS

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.

IV. DETECTION

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.

V. WORKAROUND

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. http://www.sophos.com/support/knowledgebase/article/7609.html

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 security problems.

VIII. DISCLOSURE TIMELINE

09/15/2006 Initial vendor notification
09/19/2006 Initial vendor response
10/31/2006 Coordinated public disclosure

IX. CREDIT

This vulnerability was reported to iDefense by Damian Put <pucik@overflow.pl>.

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X. LEGAL NOTICES

Copyright © 2006 iDefense, Inc.

Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDefense. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please email customerservice@idefense.com for permission.

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 author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.