Microsoft Excel Malformed Range Memory Corruption Vulnerability

Risk
High

Date Discovered
12/8/2005 12:00:00 AM

Description
An unspecified vulnerability has been reported to exist in Microsoft Excel. The vulnerability was announced on eBay. The discoverer was offering to sell the vulnerability details until the auction was terminated by eBay. According to the auction description, it is possible to have a large value passed to "msvcrt.memmove()" through data fields in an Excel .xls file. The discoverer has claimed that code execution is possible.

This entry will be updated as more details become available.

**UPDATE (Dec 9, 2005): Microsoft has confirmed that this vulnerability exists. See eWeek link in reference section. The original listing on eBay has been pulled.

**UPDATE (Mar 14, 2006): Microsoft has released security advisory MS06-012 addressing this and other issues. This issue is occurs when handling an excel file with a malformed range and can be exploited to execute code.

Symantec Vulnerability Assessment
Symantec Vulnerability Assessment detects and reports this vulnerability. Click here for the advisory released March 16, 2006.

Technologies Affected
Microsoft Excel 2000 SR1
Microsoft Excel 2000 SP2
Microsoft Excel 2000 SP3
Microsoft Excel 2000
Microsoft Excel 2002 SP2
Microsoft Excel 2002 SP1
Microsoft Excel 2002 SP3
Microsoft Excel 2002
Microsoft Excel 2003
Microsoft Excel 2003 SP1
Microsoft Excel 2004 for Mac
Microsoft Excel 95
Microsoft Excel 97
Microsoft Excel 97 SR2
Microsoft Excel 97 SR1
Microsoft Excel Viewer 2003
Microsoft Excel x for Mac

Recommendations
Do not accept or execute files from untrusted or unknown sources.
Successful exploitation of this vulnerability would require that the target user open a malicious .xls file. Do not accept such files from untrusted sources.
Run all software as a non-privileged user with minimal access rights.
Any code that is executed would run with the privileges of the user who opened the document. Do not use applications such as this on critical hosts and ensure that users are logged in as accounts with minimal privileges. This may limit the immediate impact of a successful attack.

Microsoft has released fixes to address this vulnerability in supported versions of the affected software.
Microsoft Excel 2004 for Mac :

Microsoft Patch Microsoft Office 2004 for Mac 11.2.3 Update
http://download.microsoft.com/download/9/C/9/9C90BD77-92B0-4A2A-B4CE-F41C560360CE/Office2004-1123UpdateEN.dmg

Microsoft Patch Microsoft Office 2004 for Mac 11.2.3 Update
http://download.microsoft.com/download/9/C/9/9C90BD77-92B0-4A2A-B4CE-F41C560360CE/Office2004-1123UpdateEN.dmg

Microsoft Patch Microsoft Office 2004 for Mac 11.2.3 Update
http://download.microsoft.com/download/9/C/9/9C90BD77-92B0-4A2A-B4CE-F41C560360CE/Office2004-1123UpdateEN.dmg

Microsoft Patch Microsoft Office 2004 for Mac 11.2.3 Update
http://download.microsoft.com/download/9/C/9/9C90BD77-92B0-4A2A-B4CE-F41C560360CE/Office2004-1123UpdateEN.dmg

Microsoft Patch Security Update for Excel Viewer 2003 (KB914451)
http://www.microsoft.com/downloads/details.aspx?FamilyId=7DBADBD1-0542-475B-91B5-90DD2AF2C0FC&displaylang=en

Microsoft Patch Security Update for Excel Viewer 2003 (KB914451)
http://www.microsoft.com/downloads/details.aspx?FamilyId=7DBADBD1-0542-475B-91B5-90DD2AF2C0FC&displaylang=en

Microsoft Patch Security Update for Excel Viewer 2003 (KB914451)
http://www.microsoft.com/downloads/details.aspx?FamilyId=7DBADBD1-0542-475B-91B5-90DD2AF2C0FC&displaylang=en

Microsoft Patch Security Update for Excel Viewer 2003 (KB914451)
http://www.microsoft.com/downloads/details.aspx?FamilyId=7DBADBD1-0542-475B-91B5-90DD2AF2C0FC&displaylang=en

Microsoft Patch Security Update for Excel 2003 (KB905756)
http://www.microsoft.com/downloads/details.aspx?FamilyId=AC22F83A-B409-4469-984E-6C19D8F5FE41&displaylang=en

Microsoft Patch Security Update for Excel 2003 (KB905756)
http://www.microsoft.com/downloads/details.aspx?FamilyId=AC22F83A-B409-4469-984E-6C19D8F5FE41&displaylang=en

Microsoft Patch Security Update for Excel 2003 (KB905756)
http://www.microsoft.com/downloads/details.aspx?FamilyId=AC22F83A-B409-4469-984E-6C19D8F5FE41&displaylang=en

Microsoft Patch Security Update for Excel 2003 (KB905756)
http://www.microsoft.com/downloads/details.aspx?FamilyId=AC22F83A-B409-4469-984E-6C19D8F5FE41&displaylang=en

Microsoft Patch Security Update for Excel 2003 (KB905756)
http://www.microsoft.com/downloads/details.aspx?FamilyId=AC22F83A-B409-4469-984E-6C19D8F5FE41&displaylang=en

Microsoft Patch Security Update for Excel 2002 (KB905755)
http://www.microsoft.com/downloads/details.aspx?FamilyId=643337C7-8A47-4FA3-AB58-7A916B33607D&displaylang=en

Microsoft Patch Security Update for Excel 2002 (KB905755)
http://www.microsoft.com/downloads/details.aspx?FamilyId=643337C7-8A47-4FA3-AB58-7A916B33607D&displaylang=en

Microsoft Patch Security Update for Excel 2002 (KB905755)
http://www.microsoft.com/downloads/details.aspx?FamilyId=643337C7-8A47-4FA3-AB58-7A916B33607D&displaylang=en

Microsoft Patch Security Update for Excel 2002 (KB905755)
http://www.microsoft.com/downloads/details.aspx?FamilyId=643337C7-8A47-4FA3-AB58-7A916B33607D&displaylang=en

Microsoft Patch Security Update for Excel 2002 (KB905755)
http://www.microsoft.com/downloads/details.aspx?FamilyId=643337C7-8A47-4FA3-AB58-7A916B33607D&displaylang=en

Microsoft Patch Security Update for Excel 2000 (KB905757)
http://www.microsoft.com/downloads/details.aspx?familyid=C9433440-31EF-4C18-A0C7-B595EA23F6FC&displaylang=en

Microsoft Patch Security Update for Excel 2000 (KB905757)
http://www.microsoft.com/downloads/details.aspx?familyid=C9433440-31EF-4C18-A0C7-B595EA23F6FC&displaylang=en

Microsoft Patch Security Update for Excel 2000 (KB905757)
http://www.microsoft.com/downloads/details.aspx?familyid=C9433440-31EF-4C18-A0C7-B595EA23F6FC&displaylang=en

Microsoft Patch Security Update for Excel 2000 (KB905757)
http://www.microsoft.com/downloads/details.aspx?familyid=C9433440-31EF-4C18-A0C7-B595EA23F6FC&displaylang=en

Microsoft Patch Security Update for Excel 2000 (KB905757)
http://www.microsoft.com/downloads/details.aspx?familyid=C9433440-31EF-4C18-A0C7-B595EA23F6FC&displaylang=en

References
Source: Brand new Microsoft Excel Vulnerability
URL: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7203336538

Source: eBay Pulls Bidding for MS Excel Vulnerability
URL: http://www.eweek.com/article2/0,1759,1899697,00.asp?kc=EWRSS03129TX1K0000614

Source: Microsoft Security Bulletin MS06-012 - Vulnerabilities in Microsoft Office Could
URL: http://www.microsoft.com/technet/security/Bulletin/MS06-012.mspx

Credits
Discovery credited to "fearwall".

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