Public Vulnerability Reports

Microsoft Word FIB Processing Stack Buffer Overflow Vulnerability

11.10.09

BACKGROUND

Microsoft Word is a word processing application that is part of the Microsoft Office suite of products. For more information about Microsoft Word, see following web site.

http://office.microsoft.com/en-us/word/default.aspx

DESCRIPTION

Remote exploitation of a stack buffer overflow vulnerability in Microsoft Corp.'s Word could allow attackers to execute arbitrary code with the privileges of the targeted user.

This vulnerability occurs when Word parses the File Information Block (FIB) structure inside a Word document. When a malformed FIB structure is processed, a stack buffer overflow will occur which can lead to an exploitable condition.

ANALYSIS

Exploitation allows remote attackers to execute arbitrary code on the affected host under the context of the user opening the file.

Exploitation might require that the user open a specially crafted word document with a vulnerable application. The most likely exploitation vector involves convincing a user to open a word document sent to them via e-mail or linked on a website.

DETECTION

iDefense has confirmed fully patched Microsoft Word 2003 SP3, Microsoft Word XP SP3, Microsoft Word 2000 SP3 are vulnerable.

Microsoft Word 2007 SP1 is not affected.

WORKAROUND

iDefense is currently unaware of any effective workaround for this issue. Since the vulnerability occurs in the core parsing code, it is not possible to disable the affected module.

User awareness is the best defense against this type of attack. Users should not follow links or open attachments from untrusted sources or that are received unexpectedly from trusted sources.

VENDOR RESPONSE

Microsoft Corp. has released a patch which addresses this issue. Information about downloadable vendor updates can be found by clicking on the URLs shown.

http://www.microsoft.com/technet/security/bulletin/MS09-068.mspx

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2009-3135 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

03/06/2009 - Initial Contact
03/07/2009 - Initial Response
05/21/2009 - Tentative disclosure set for September
06/25/2009 - Requested CVE from Vendor
11/10/2009 - Coordinated Public Disclosure

CREDIT

This vulnerability was discovered by Jun Mao, iDefense Labs.

Get paid for vulnerability research
http://labs.idefense.com/methodology/vulnerability/vcp.php

Free tools, research and upcoming events
http://labs.idefense.com/

LEGAL NOTICES

Copyright © 2009 Verisign, 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 customer service 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.