Excel Security Problem

[just_jon]

FYI --

Microsoft Excel Invalid Column Heap Corruption Vulnerability

iDefense Security Advisory 01.09.07
http://labs.idefense.com/intelligence/vulnerabilities/
Jan 09, 2007

I. BACKGROUND

Microsoft Excel is the spreadsheet application from the Microsoft Office
System. More information is available at the following link:

http://office.microsoft.com/

II. DESCRIPTION

Remote exploitation of an input validation error in Microsoft Corp.'s
Excel spreadsheet application may allow the execution of arbitrary code.

The vulnerability specifically exists in the handling of out of range
values in the column field in several BIFF8 record types. By supplying
an invalid Column field to one of these records, it is possible to cause
the system to reference arbitrary memory. This can be exploited to gain
control of the application.

III. ANALYSIS

Successful exploitation of this vulnerability would allow an attacker to
execute arbitrary code in the context of the user who opened the
document.
In order exploit this vulnerability, an attacker would need to convince
the target to open an Excel spreadsheet file. Likely attack vectors
include sending the file as an attachment in an email or linking to the
file on a website.

Systems with a default install of Office 2000 will open Office
documents, including Excel spreadsheet files, from websites without
prompting the user. This allows an attacker to exploit this
vulnerability without user interaction beyond visiting a website. Later
versions of Office will not open these documents automatically unless
the user has chosen this behavior.

IV. DETECTION

iDefense has confirmed the existence of this vulnerability in Microsoft
Excel 2003 with all available service packs and security patches.
Previous versions of Excel are also likely to be affected.

V. WORKAROUND

Do not follow links or open files from unknown sources or that you were
not expecting to receive.

VI. VENDOR RESPONSE

Microsoft has addressed this vulnerability with Microsoft Security
Bulletin MS07-002. A link to this bulletin can be found below.

http://www.microsoft.com/technet/security/bulletin/ms07-002.mspx

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2007-0030 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

09/14/2006 Initial vendor notification
09/15/2006 Initial vendor response
01/09/2007 Coordinated public disclosure

IX. CREDIT

This vulnerability was discovered by Greg MacManus, iDefense Labs.

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

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X. LEGAL NOTICES

Copyright (c) 2006 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
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customerservice@idefense.com 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.