iDefense Security Advisory 03.11.08
http://labs.idefense.com/intelligence/vulnerabilities/
Mar 11, 2008

I. BACKGROUND

Microsoft Excel is the spreadsheet application that is included with
Microsoft Corp's Office productivity software suite. More information
is available at the following website.

http://office.microsoft.com/excel/

II. DESCRIPTION

Remote exploitation of a memory corruption vulnerability in Microsoft
Corp.'s Excel 2003 could allow attackers to execute arbitrary code in
the context of the currently logged on user.

This vulnerability specifically exists due to the improper handling of
malformed formulas. By creating a document containing a specially
crafted formula, an attacker is able to cause memory corruption that
leads to arbitrary code execution.

III. ANALYSIS

Exploitation allows an attacker to execute arbitrary code in the context
of the currently logged on user. In order to exploit this vulnerability,
the attacker must persuade a user to open a specially crafted Excel
(XLS) document. Likely attack vectors include sending the file as an
e-mail attachment or linking to the file on a website.

IV. DETECTION

iDefense has confirmed the existence of this vulnerability in Excel 2003
SP2. Other versions may also be affected.

V. WORKAROUND

Disabling support for legacy binary file formats in the registry will
prevent exploitation of this issue. However, this workaround is not
available for all versions of Microsoft Excel.

VI. VENDOR RESPONSE

Microsoft has officially addressed this vulnerability with Security
Bulletin MS08-014. A fix for this issue was originally included as part
of Office 2003 SP3. For more information, consult their bulletin at the
following URL.

http://www.microsoft.com/technet/security/Bulletin/ms08-014.mspx

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2008-0115 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

07/27/2007  Initial vendor notification
07/27/2007  Initial vendor response
03/11/2008  Coordinated public disclosure

IX. CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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X. LEGAL NOTICES

Copyright © 2008 iDefense, 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.