SECUNIA ADVISORY ID: SA28506

VERIFY ADVISORY: http://secunia.com/advisories/28506/

CRITICAL: Extremely critical

IMPACT: System access

SOFTWARE:
Microsoft Excel 2003: http://secunia.com/product/4970/
Microsoft Excel Viewer 2003: http://secunia.com/product/7700/
Microsoft Excel 2002: http://secunia.com/product/4043/
Microsoft Excel 2000: http://secunia.com/product/3054/
Microsoft Office 2000: http://secunia.com/product/24/
Microsoft Office 2003 Professional Edition: http://secunia.com/product/2276/
Microsoft Office 2003 Small Business Edition: http://secunia.com/product/2277/
Microsoft Office 2003 Standard Edition: http://secunia.com/product/2275/
Microsoft Office 2003 Student and Teacher Edition: http://secunia.com/product/2278/
Microsoft Office 2004 for Mac: http://secunia.com/product/8713/

DESCRIPTION: A vulnerability has been reported in Microsoft Excel, which can be exploited by malicious people to compromise a user's system. The vulnerability is caused due to an unspecified error in the handling of Excel files and can be exploited via a specially crafted Excel file with malformed header information. Successful exploitation allows execution of arbitrary code but requires that the user is tricked into opening a malicious Excel file. NOTE: According to Microsoft, this is currently being actively exploited.

The vulnerability is reported in the following versions:
* Microsoft Office Excel 2003 Service Pack 2
* Microsoft Office Excel Viewer 2003
* Microsoft Office Excel 2002
* Microsoft Office Excel 2000
* Microsoft Excel 2004 for Mac.

SOLUTION: Do not open untrusted Excel files. For Microsoft Excel 2003, the vendor recommends using the Microsoft Office Isolated Conversion Environment (MOICE) or Microsoft Office File Block policy. Please see the vendor's advisory for details.

PROVIDED AND/OR DISCOVERED BY: Discovered as a 0-day.

ORIGINAL ADVISORY: Microsoft (KB947563): http://www.microsoft.com/technet/security/advisory/947563.mspx