Public Vulnerability Reports

VMware VMnc Codec Heap Overflow Vulnerability

04.09.10

BACKGROUND

VMware Inc. markets several virtualization products such as ACE, Player, Server, and Workstation. These products include a video coder-decoder (codec) called 'vmnc.dll', or VMware Movie Decoder, that is registered on the host machine at installation time. This codec will be used whenever video streams of the 'VMnc' type, such as those produced when using VMware Workstation's "Capture Movie" feature, are encountered. For more information, refer to the links shown below.

http://en.wikipedia.org/wiki/Codec

http://www.vmware.com/support/ws5/doc/ws_running_capture.html

DESCRIPTION

Remote exploitation of a heap-based buffer overflow vulnerability in VMware Inc.'s movie decoder allows attackers to execute arbitrary code.

This vulnerability exists due to a lack of input validation when processing certain specially crafted Audio-Video Interleave (AVI) files. During processing, a heap buffer will be allocated based on one part of the AVI file data. However, the amount of data copied into that buffer is calculated based on a different part of the file. This leads to an exploitable heap-based buffer overflow condition.

ANALYSIS

Exploitation of this vulnerability results in the execution of arbitrary code with the privileges of the user running an application utilizing the vulnerable codec. In order to reach the vulnerable code, a targeted user must play a specially crafted AVI media file. An attacker typically accomplishes this via social engineering or injecting content into compromised, trusted sites.

DETECTION

iDefense confirmed the existence of this vulnerability using the following software.

 vmnc.dll version 6.5.2.7026 from Workstation 6.5.2 vmnc.dll version 6.5.3.8888 from Workstation 6.5.3 

A full list of affected VMware products can be found in Security Advisory VMSA-2010-0007.

WORKAROUND

Disabling the 'VMnc' codec will prevent exploitation. In order to do so, import the 'disable-vmnc-codec.reg' registry file as follows.

 Windows Registry Editor Version 5.00 [HKEY_LOCAL_MACHINESOFTWAREWow6432NodeMicrosoftWindows NTCurrentVersionDrivers32] "VIDC.VMnc"=- [HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersionDrivers32] "VIDC.VMnc"=- 

VENDOR RESPONSE

VMware Inc. has released patches to address this issue. Information about downloadable vendor updates can be found by clicking on the URLs shown. http://lists.vmware.com/pipermail/security-announce/2010/000090.html

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2010-1564 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org/), which standardizes names for security problems.

DISCLOSURE TIMELINE

08/25/2009 Initial Vendor Notification
08/25/2009 Initial Vendor Reply
04/09/2010 Coordinated Public Disclosure

CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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LEGAL NOTICES

Copyright © 2010 Verisign, Inc.

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