Microsoft Excel 2003 SP3 and Office 2008 for Mac do not properly handle memory during the opening of files, which allows remote attackers to execute arbitrary code via a crafted spreadsheet, aka "Excel Memory Corruption Using Various Modified Bytes Vulnerability."
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A15064
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2012/ms12-030
http://www.us-cert.gov/cas/techalerts/TA12-129A.html
http://www.securitytracker.com/id?1027041