The MSRC has released an advisory 969136 about a vulnerability in Microsoft Office PowerPoint which is being exploited in the wild. Office 2000, Office XP, Office 2003 and Mac Office are vulnerable however the latest version, Office 2007, is not. Usually, these files look legit when opened, the malicious PPT files try to drop malware once opened.
Here is a screenshot with the process activity after a malicious document has been executed:
More info: MS Threat Research & Response Blog