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TUCoPS :: VMWare :: bx6111.htm

VMware VMnc Codec Heap Overflow Vulnerability
iDefense Security Advisory 04.09.10: VMware VMnc Codec Heap Overflow Vulnerability
iDefense Security Advisory 04.09.10: VMware VMnc Codec Heap Overflow Vulnerability

iDefense Security Advisory 04.09.10 
Apr 09, 2010


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



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


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 =A9 2010 iDefense, Inc.

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Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
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