Secunia Research Advisory

Microsoft Excel rtWnDesk Record Memory Corruption Vulnerability


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                     Secunia Research 15/08/2007

 - Microsoft Excel rtWnDesk Record Memory Corruption Vulnerability -

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Table of Contents

Affected Software....................................................1
Severity.............................................................2
Vendor's Description of Software.....................................3
Description of Vulnerability.........................................4
Solution.............................................................5
Time Table...........................................................6
Credits..............................................................7
References...........................................................8
About Secunia........................................................9
Verification........................................................10

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1) Affected Software 

Microsoft Office Excel 2000, XP, 2003, 2003 Viewer, 2004 for Mac.

NOTE: Other versions may also be affected.

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2) Severity 

Rating: Highly critical
Impact: System access
Where:  From remote

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3) Vendor's Description of Software 

"Organize, analyze and present your data with precision and panache.".

Product Link:
http://office.microsoft.com/en-us/excel/

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4) Description of Vulnerability

Secunia Research has discovered a vulnerability in Microsoft Excel,
which can be exploited by malicious people to compromise a user's
system.

The vulnerability is caused due to an error when validating an index
value in the rtWnDesk record and can be exploited to corrupt memory
via a specially crafted Excel Workspace (XLW) file. A negative index
value will cause a pointer to reference memory outside of an
allocated buffer. Subsequent records will read and write to the user
controlled location.

Successful exploitation may allow execution of arbitrary code.

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5) Solution 

Install the patch released with MS07-044 (KB940965):
http://www.microsoft.com/technet/security/Bulletin/MS07-044.mspx

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6) Time Table 

17/07/2007 - Vendor notified.
18/07/2007 - Vendor response.
15/08/2007 - Public disclosure.

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7) Credits 

Discovered by Dyon Balding, Secunia Research.

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8) References

The Common Vulnerabilities and Exposures (CVE) project has assigned 
CVE-2007-3890 for the vulnerability.

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9) About Secunia

Secunia offers vulnerability management solutions to corporate
customers with verified and reliable vulnerability intelligence
relevant to their specific system configuration:

https://www.flexera.com/

Secunia also provides a publicly accessible and comprehensive advisory
database as a service to the security community and private 
individuals, who are interested in or concerned about IT-security.

Secunia believes that it is important to support the community and to
do active vulnerability research in order to aid improving the 
security and reliability of software in general.

Secunia regularly hires new skilled team members. Check the URL below 
to see currently vacant positions:

https://www.flexera.com/company/careers

Secunia offers a FREE mailing list called Secunia Security Advisories:

https://www.flexera.com/secunia_security_advisories/ 

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10) Verification 

Please verify this advisory by visiting the Secunia website:
https://www.flexera.com/about-us/secunia-research/advisories/sr-2007-65.html

Complete list of vulnerability reports published by Secunia Research:
https://www.flexera.com/about-us/secunia-research/advisories/

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