Microsoft Office Excel 2000 SP3, 2002 SP3, 2003 SP3, and 2007 SP1; Excel Viewer 2003 Gold and SP3; Excel Viewer; Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats SP1; and Excel in Microsoft Office 2004 and 2008 for Mac allow remote attackers to execute arbitrary code via a crafted Excel document that triggers an access attempt on an invalid object, as exploited in the wild in February 2009 by Trojan.Mdropper.AC.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A5968
https://exchange.xforce.ibmcloud.com/vulnerabilities/48875
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2009/ms09-009
http://www.vupen.com/english/advisories/2009/1023
http://www.us-cert.gov/cas/techalerts/TA09-104A.html
http://www.symantec.com/business/security_response/writeup.jsp?docid=2009-022310-4202-99
http://www.securityfocus.com/bid/33870
http://www.microsoft.com/technet/security/advisory/968272.mspx
http://securitytracker.com/id?1021744