US-CERT Technical Cyber Security Alert TA06-139A -- Microsoft Word Vulnerability

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                 National Cyber Alert System

           Technical Cyber Security Alert TA06-139A

Microsoft Word Vulnerability

Original release date: May 19, 2006
Last revised: –
Source: US-CERT

Systems Affected

 * Microsoft Word 2003
 * Microsoft Word XP (2002)

Microsoft Word is included in Microsoft Works Suite and Microsoft
Office. Other versions of Word, and other Office programs may be
affected or act as attack vectors.

Overview

A buffer overflow vulnerability in Microsoft Word could allow an
attacker to execute arbitrary code on a vulnerable system.

I. Description

Microsoft Word contains a buffer overflow vulnerability. Opening a
specially crafted Word document, including documents hosted on web
sites or attached to email messages, could trigger the
vulnerability.

Office documents can contain embedded objects. For example, a
malicious Word document could be embedded in an Excel or PowerPoint
document. Office documents other than Word documents could be used
as attack vectors.

For more information, please see Vulnerability Note VU#446012.

II. Impact

By convincing a user to open a specially crafted Word document, an
attacker could execute arbitrary code on a vulnerable system. If
the user has administrative privileges, the attacker could gain
complete control of the system.

III. Solution

At the time of writing, there is no complete solution available.
Consider the following workarounds:

Do not open untrusted Word documents

Do not open unfamiliar or unexpected Word or other Office
documents, including those received as email attachments or hosted
on a web site.  Please see Cyber Security Tip ST04-010 for more
information.

Do not rely on file extension filtering

In most cases, Windows will call Word to open a document even if
the document has an unknown file extension. For example, if
document.d0c (note the digit "0") contains the correct file header
information, Windows will open document.d0c with Word.

Appendix A. References

 * Vulnerability Note VU#446012 -
   <http://www.kb.cert.org/vuls/id/446012>

 * Cyber Security Tip ST04-010 -
   <http://www.us-cert.gov/cas/tips/ST04-010.html>

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Information used in this document came from SANS and Microsoft.

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The most recent version of this document can be found at:

 <http://www.us-cert.gov/cas/techalerts/TA06-139A.html>

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Feedback can be directed to US-CERT Technical Staff. Please send
email to <[email protected]> with "TA06-139A Feedback VU#446012" in the
subject.

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Produced 2006 by US-CERT, a government organization.

Terms of use:

 <http://www.us-cert.gov/legal.html>

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Revision History

May 19, 2006: Initial release

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