This indicates an attack attempt to exploit a remote Code Execution vulnerability in Microsoft Office Outlook email client.
The vulnerability is due to a error when parsing the contents of an S/MIME message. A remote attacker could exploit this to execute arbitrary code execution within the context of the application, via a crafted email.
Microsoft Office Outlook 2007
Microsoft Office Outlook 2010
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.