Microsoft released Office 2004 11.3.7, an update to address an important security problem with remote code execution. The Office 2004 11.3.6 update is a pre-requisite.

Microsoft Security Bulletin MS07-044 – Critical
This security update resolves a privately reported vulnerability in addition to other security issues identified during the course of the investigation. These vulnerabilities could allow remote code execution if a user opens a specially crafted Excel file. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.