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Microsoft Excel LABELSST Record Memory Corruption Vulnerability



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


Remote exploitation of a memory corruption vulnerability in Microsoft Corp.'s Excel could allow an attacker to execute arbitrary code with the privileges of the current user.

The vulnerability occurs when Excel parses a specially crafted LABELSST record in an Excel file. A specific length value of the LABELSST record will cause the application to treat a value from the file as a pointer and modify memory content at that address. This leads to memory corruption and may allow arbitrary code execution.


Exploitation of this vulnerability results in the execution of arbitrary code with the privileges of the user opening the file. To exploit this vulnerability, an attacker needs to convince a user to open a malicious file. Attackers typically accomplish this by e-mailing a targeted user the file or hosting the file on a Web page.


Microsoft Excel 2003 SP3 and Office 2004 for Mac are vulnerable.


iDefense is unaware of any workaround for this issue.


Microsoft has released updates to address this vulnerability. For more information, consult their advisory at the following URL.


The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2011-3403 to this issue. This is a candidate for inclusion in the CVE list (, which standardizes names for security problems.


06/08/2011 Initial Vendor Notification
06/08/2011 Initial Vendor Reply
12/13/2011 Coordinated Public Disclosure


The discoverer of this vulnerability wishes to remain anonymous.

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Copyright © 2011 Verisign, Inc.

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