This indicates an attack attempt to exploit a Remote Code Execution vulnerability in Microsoft Office.
The vulnerability is due to improper handling of certain objects when the vulnerable software attempts to access a specially crafted MS Office file. An attacker can exploit this to execute arbitrary code within the context of the logged in user via a crafted office file.
Microsoft Office 2007
Microsoft Office 2010
Microsoft Office 2013
Microsoft Office 2013 RT
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.