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Security Services

VMware VMnc Codec Heap Overflow Vulnerability



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.


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.


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.


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

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

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


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"=- 


VMware Inc. has released patches to address this issue. Information about downloadable vendor updates can be found by clicking on the URLs shown.


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 (, which standardizes names for security problems.


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


The discoverer of this vulnerability wishes to remain anonymous.

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Copyright © 2010 Verisign, Inc.

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