Public Vulnerability Reports

Microsoft Office Web Components 2000 Buffer Overflow Vulnerability



Office Web Components is a group of ActiveX controls that can be used to view and edit Microsoft Office files such as spreadsheets and charts. It is commonly used to allow a user to edit a spreadsheet in the browser. The controls are installed with a default installation of Microsoft Office. More information can be found at the vendor's website at the following address.


Remote exploitation of a stack based buffer overflow vulnerability in Microsoft Corp.'s Office Web Components 2000 could allow an attacker to execute arbitrary code with the privileges of the logged on user.

When instantiating a Spreadsheet object, it is possible to pass the object a parameter that refers to an Excel file that will be retrieved and then loaded. By using a long string for the parameter, it is possible to case a stack based buffer overflow.


Exploitation results in the execution of arbitrary code with the privileges of the logged-on user. Exploitation would require that an attacker hosts a maliciously crafted page on a Web site and entice users to visit the site. No further action is needed other than following a link to a malicious Web page.


iDefense has confirmed the existence of this vulnerability in Microsoft Office XP Service Pack 3. Microsoft reports that the following products are affected:

 Microsoft Office XP Service Pack 3 Microsoft Office 2000 Web Components SP3 Microsoft Office XP Web Components SP3 Microsoft BizTalk Server 2002 Visual Studio .NET 2003 Service Pack 1 


Setting the kill bit for the following CLSIDs will mitigate the threat from web based attacks conducted through Internet Explorer. The CLSID for the vulnerable control is:



Microsoft has released a patch which addresses this issue. For more information, consult their advisory at the following URL:


The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2009-1534 to this issue. This is a candidate for inclusion in the CVE list (, which standardizes names for security problems.


03/17/2008 Initial vendor notification
03/17/2008 Initial vendor response
03/17/2008 PoC requested
03/17/2008 Poc sent
04/18/2008 Status update request sent
05/28/2008 Status update request sent
07/03/2008 Status update received, new case manager assigned
06/26/2009 Status update received, new case manager assigned
06/26/2009 Bulletin release scheduled for July
07/09/2009 Status update received, bulletin delayed
08/11/2009 Public disclosure by Microsoft


This vulnerability was discovered by Sean Larsson, iDefense Labs.

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Copyright © 2009 Verisign, Inc.

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