Microsoft Visual Basic for Applications Document Check Buffer Overflow Vulnerability



Date Discovered

August 8, 2006


A vulnerability has been discovered in Microsoft Visual Basic for Applications. The vulnerability occurs due to insufficient bounds checking when checking the properties of malicious documents. As a result, a malformed document may be able to trigger a buffer-overflow within the affected application, effectively allowing for the execution of arbitrary code. Microsoft Office, Access, Visio, Word, and Works are also reportedly attack vectors, since they employ VBA when handling certain document types. Email is another potential attack vector for this vulnerability, but merely opening an email would not trigger the issue; replying or forwarding the message could potentially trigger it. Microsoft has reported that this issue is being exploited in the wild.

Technologies Affected

  • Microsoft Access 2000 SP3
  • Microsoft Office 2000 SP3
  • Microsoft Office XP SP3
  • Microsoft Project 2000 SR1
  • Microsoft Project 2002 SP1
  • Microsoft Visio 2002 SP2
  • Microsoft Visual Basic for Applications SDK 6.0
  • Microsoft Visual Basic for Applications SDK 6.2
  • Microsoft Visual Basic for Applications SDK 6.3
  • Microsoft Visual Basic for Applications SDK 6.4
  • Microsoft Works Suite 2004
  • Microsoft Works Suite 2005
  • Microsoft Works Suite 2006
  • Nortel Networks Contact Center - CCT
  • Nortel Networks Contact Center
  • Nortel Networks Contact Center Express
  • Nortel Networks Contact Center Manager
  • Nortel Networks Contact Center Manager Server


Deploy network intrusion detection systems to monitor network traffic for malicious activity.
Deploy NIDS to monitor network traffic for signs of suspicious or anomalous activity. This may help detect malicious actions that an attacker may take after successfully exploiting vulnerabilities in applications. Review all applicable logs regularly.

Do not accept or execute files from untrusted or unknown sources.
Users should never accept files from untrusted or unknown sources, because they may be malicious in nature. Avoid opening email attachments from unknown or questionable sources.

Do not accept or execute files from untrusted or unknown sources.
Avoid opening documents received unexpectedly, especially those supplied by untrustworthy or suspicious persons. These documents may be designed to exploit this or other potentially latent vulnerabilities.

Do not follow links provided by unknown or untrusted sources.
Users should avoid websites of questionable integrity. Never follow links supplied by unknown or untrusted sources.

When possible, limit the privileges granted to users to the least amount required.
Invoke all applications with the least privileges required to function. This may greatly reduce the consequences of an attacker gaining the ability to execute arbitrary code with the privileges of the application.

Microsoft has released updates that address this issue. Patches have been included for Office and other affected products. Please see the vendor advisory for more information.



Ka Chun Leung of Symantec is credited with the discovery of this vulnerability.

© 1995- Symantec Corporation

Permission to redistribute this alert electronically is granted as long as it is not edited in any way unless authorized by Symantec Security Response. Reprinting the whole or part of this alert in any medium other than electronically requires permission from


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.

Symantec, Symantec products, Symantec Security Response, and are registered trademarks of Symantec Corp. and/or affiliated companies in the United States and other countries. All other registered and unregistered trademarks represented in this document are the sole property of their respective companies/owners.