Microsoft Office Excel 2000 SP3 allows remote attackers to execute arbitrary code via a crafted Excel spreadsheet that contains a malformed object, which triggers memory corruption during the loading of records from this spreadsheet, aka "File Format Parsing Vulnerability." http://www.microsoft.com/technet/security/Bulletin/MS08-074.mspx
A remote code execution vulnerability exists in Microsoft Office Excel as a result of memory corruption when loading Excel records. The vulnerability could allow remote code execution if a user opens a specially crafted Excel file that includes a malformed object. An attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.