A memory corruption vulnerability was found in Microsoft Forefront Endpoint Protection 2010 and Microsoft Security Essentials. By exploiting this vulnerability malicious users can execute arbitrary code. This vulnerability can be exploited remotely via a specially crafted file.

Microsoft Forefront Endpoint Protection 2010
Microsoft Security Essentials

Install necessary updates from the KB section, that are listed in your Windows Update (Windows Update usually can be accessed from the Control Panel)

The following public exploits exists for this vulnerability:

https://www.exploit-db.com/exploits/44402

Malware exists for this vulnerability. Usually such malware is classified as Exploit. More details.