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Microsoft Office Works Converter Heap Overflow Vulnerability

02.12.08

BACKGROUND

Microsoft Works is a word processor created by Microsoft in the 1980s. Microsoft Office, a widely use productivity suite, is distributed with converters for various versions of the Works file format.

DESCRIPTION

Remote exploitation of a heap corruption vulnerability in Microsoft Corp.'s Works Converter, as included with Microsoft Office, could potentially allow an attacker to execute arbitrary code as the current user.

This vulnerability stems from improper input validation of OLE structures within wkcvqd01.dll when converting a Microsoft Works document (WPS extension) to Rich Text Format (RTF). When certain fields are modified, such as the length or count values, heap corruption can occur. This leads to a potentially exploitable condition.

ANALYSIS

Exploitation allows attackers to execute arbitrary code as the user that converts a specially crafted Works document.

Exploitation might require the installation of additional Microsoft Office components. When installing Microsoft Office, there are several installation options for converters. In corporate environments, the required components are usually set to be installed from the hard drive on first use. However, one of the installation options causes a request for the installation media. If this option is used, the media prompt may help mitigate exploitation.

Microsoft first released a fix for this vulnerability as part of Office 2003 SP3. No specific mention was made about this vulnerability at that time.

DETECTION

iDefense has confirmed that wkcvqd01.dll version 7.03.0616.0, as included with Microsoft Office 2003, is vulnerable to this issue. Older versions are assumed to be vulnerable as well. Additionally, Microsoft Works itself is suspected to be vulnerable.

WORKAROUND

User awareness is the best defense against this type of attack. Users should be reminded not to open attachments or click URLs from untrusted sources.

VENDOR RESPONSE

Microsoft has officially addressed this vulnerability with Security Bulletin MS08-011. For more information, consult their bulletin at the following URL.

http://www.microsoft.com/technet/security/Bulletin/ms08-011.mspx

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2007-0216 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

11/13/2006 Initial vendor notification
11/14/2006 Initial vendor response
09/17/2007 Office 2003 SP3 released (fix included)
02/12/2008 Coordinated public disclosure

CREDIT

This vulnerability was reported to VeriSign iDefense by Damian Put (pucik@overflow.pl).

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LEGAL NOTICES

Copyright © 2008 Verisign, 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 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.