Kaspersky Anti-Virus Engine CHM File Parser Buffer Overflow
Vulnerability

iDEFENSE Security Advisory 10.10.05
www.idefense.com/application/poi/display?id=318&type=vulnerabilities 
October 10, 2005

I. BACKGROUND

Kaspersky Anti-Virus Engine (KAV) is a popular virus scanning engine 
for Windows and Linux. The Kaspersky Anti-Virus Engine is commonly 
included in various vendors' network mail gateway and host-based anti-
virus products. 

II. DESCRIPTION

Remote exploitation of a buffer overflow vulnerability in Kaspersky 
Labs' Anti-Virus Engine allows remote attackers to execute arbitrary 
code. Kaspersky Anti-Virus Engine is used by multiple vendors in Linux 
virus scanner products and exploitation requires minimal interaction by 
a targeted user.

The Kasperksy Anti-Virus Engine (KAV) is found in many gateway and 
host-based anti-virus scanners. The vulnerability specifically exists 
in the CHM file parser within the KAV engine. When a corrupt CHM file 
is scanned by the KAV engine, a heap overflow can occur which allows 
remote attackers to execute arbitrary code with permissions of the 
anti-virus application's process, usually user privileges. On Microsoft 
platforms, affected software has not been shown to execute arbitrary 
code, however Kaspersky Anti-Virus will fail to scan any files after a 
corrupt CHM file has been encountered, thus allowing further malicious 
codes to reach the target.

III. ANALYSIS

Successful exploitation of the vulnerability can result in remote 
arbitrary code execution or the disabling of anti-virus functionality. 
In the case of Linux platforms, specifically network gateways, user 
interaction is not required and can lead to the compromise of trusted 
systems. In addition, compromising mail gateways can lead to further 
compromise of internal hosts by injecting malicious code into mail 
attachments.

IV. DETECTION

iDEFENSE Labs has confirmed the existence of this vulnerability in the 
following products (tested April 2005):

    * Kaspersky Personal 5.0.227
    * Kaspersky Anti-Virus On-Demand Scanner for Linux 5.0.5
    * F-Secure Anti-Virus for Linux 4.50

All products utilizing the Kaspersky Anti-Virus engine are potentially 
vulnerable.

The vendor has notified iDEFENSE that the vulnerability has been 
addressed via a signature update. Users who have updated their 
signatures after July 2005 are reportedly not affected.    

V. WORKAROUND

iDEFENSE is currently unaware of any effective workarounds for this 
issue. 

VI. VENDOR RESPONSE

The vendor has notified iDEFENSE that the vulnerability has been 
addressed via a signature update. Users who have updated their 
signatures after July 2005 are reportedly not affected. Update your 
anti-virus signatures to ensure the vulnerability has been addressed.

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-2937 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

06/20/2005  Initial vendor notification
10/05/2005  Initial vendor response
10/10/2005  Public disclosure

IX. CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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X. LEGAL NOTICES

Copyright (c) 2005 iDEFENSE, Inc.

Permission is granted for the redistribution of this alert
electronically. It may not be edited in any way without the express
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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.