Microsoft Visual Basic for Applications Remote Code Execution Vulnerability

Date Published : 08 August 2006

Date Last Revised : 08 August 2006

Overview : A remote code execution vulnerability exists in the way that Visual Basic for Applications (VBA) checks the document properties that a host application passes to it when opening a document.

This vulnerability has been classified as "High Risk." Computer users should take appropriate action to patch vulnerable systems.

Description : The vulnerability results from the way that VBA checks certain document properties that a host application passes to it when opening a document. As a result, it is possible for the host application to pass unchecked parameters to VBA, causing a buffer overrun condition that could allow arbitrary code to be executed.

Microsoft VBA is a development technology for developing client desktop packaged applications and integrating them with existing data and systems. Microsoft VBA is based on the Microsoft Visual Basic development system. Microsoft Office products include VBA and make use of VBA to perform certain functions. VBA can also be used to build customized applications based around an existing host application.

An attacker who successfully exploited this vulnerability could take complete control of an affected system.

Impact : In order for an attack to be successful, a user would have to open a specially crafted document sent to them by an attacker. This document could be any type of document that supports VBA, such as a Word document, Excel spreadsheet, PowerPoint presentation. In the case where Microsoft Word is being used as the HTML e-mail editor for Microsoft Outlook, this document could be an e-mail message; however, the user would need to reply to or forward the message in order for the vulnerability to be exploited.

In a Web-based attack scenario, an attacker could host a Web site that contains a Web page that is used to exploit this vulnerability. In addition, compromised Web sites and Web sites that accept or host user-provided content or advertisements could contain specially crafted content that could exploit this vulnerability. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to persuade users to visit the Web site, typically by getting them to click a link in an e-mail message or instant messenger message that takes users to the attacker's Web site.

An attack that is successfully exploited would enable an attacker to install malicious code (worm, virus, Trojan horse), read confidential data, or take control over the target system.

Platforms Affected : Please review the Microsoft Security Bulletin MS06047 for a complete list of affected platforms: http://www.microsoft.com/technet/security/bulletin/MS06047.mspx

ZoneAlarm Products That Provide Protection : To ensure the most comprehensive protection, computer users should employ ZoneAlarm Security Suite, or ZoneAlarm Pro. Zone Labs products are not vulnerable to this attack. All Zone Labs security products, including ZoneAlarm, protect the user's system from unauthorized access and intrusions, and alert the user when malicious code attempts to access the network.

Recommended Actions :

ZoneAlarm Family

ZoneAlarm Pro and ZoneAlarm Security Suite protect your system against this vulnerability through "Internet Zone Security" and "Trusted Zone Security". It is recommended that you ensure the following:

• Internet Zone Security is set to High.
• Trusted Zone Security is set to Medium.
• Only trusted hosts are in the 'Trusted' Zone.

Check Point Integrity

Check Point Integrity protects your system against this vulnerability through the following available services:

Classic Firewall Rules

It is recommended that you ensure:

• Only trusted hosts are in the 'Trusted' Zone.

SmartDefense Program Advisor

SmartDefense Program Advisor automatically blocks malware. It is recommended that you ensure the following:

• Internet Zone Security is set to High.
• Trusted Zone Security is set to Medium.

For more information about activating SmartDefense Program Advisor, please refer to CPSA200510 .

Advanced Cooperative Enforcement

• Use Advanced Cooperative Enforcement to enforce policy upon remote endpoints.

Related Resources :

Install Microsoft patches to remove this vulnerability from the Windows Operating System and other software components: http://windowsupdate.microsoft.com

Review Microsoft Security Bulletin MS06047: http://www.microsoft.com/technet/security/Bulletin/MS06047.mspx

Disclaimer : The information in this 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.

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