iDefense Security Advisory 02.12.08 http://labs.idefense.com/intelligence/vulnerabilities/ Feb 12, 2008 I. BACKGROUND Microsoft Word is a word processing application which is heavily used in corporate environments. Word comes with Office Converters that allow it to import files from various formats such as old versions of other word processing software. More information can be found on the vendor's site at the following URL. http://office.microsoft.com/ II. DESCRIPTION Remote exploitation of a buffer overflow vulnerability in Microsoft Corp.'s Works Converter allows attackers to execute arbitrary code as the current user. This vulnerability stems from improper input validation of section length headers 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, a stack-based buffer overflow occurs. This leads to a directly exploitable condition. III. 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. In order to exploit this vulnerability, the targeted user must manually choose to open the malformed Works document in Microsoft Word. The file extension is not registered by default. IV. DETECTION iDefense confirmed that wkcvqd01.dll version 7.03.0616.0, as included with Microsoft Office 2003, is vulnerable. Older versions of Microsoft Office as well as Microsoft Works are also assumed vulnerable. V. WORKAROUND User awareness is the best defense against this type of attack. Users should not open attachments or click URLs from untrusted or unknown sources. VI. 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 VII. CVE INFORMATION The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2008-0108 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org/), which standardizes names for security problems. VIII. DISCLOSURE TIMELINE 06/14/2007 Initial vendor notification 06/14/2007 Initial vendor response 02/12/2008 Coordinated public disclosure IX. CREDIT This vulnerability was reported to VeriSign iDefense by sillypea. Get paid for vulnerability research http://labs.idefense.com/methodology/vulnerability/vcp.php Free tools, research and upcoming events http://labs.idefense.com/ X. LEGAL NOTICES Copyright © 2008 iDefense, Inc. Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDefense. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please e-mail customerservice@xxxxxxxxxxxx for permission. 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.
