This indicates an attack attempt against a buffer-overflow vulnerability in Microsoft Office.
The vulnerability is caused by an error when "GIFIMP32.FLT" handles a malicious GIF file. It allows a remote attacker to execute arbitrary code via sending a crafted GIF file.
Microsoft Office 2003 SP1 and SP2, Office XP SP3, Office 2000 SP3, and other products.
Apply the vendor update: