Antimalware Engine 1.1.7801.0 was released to customers on 18 Oct 2011

Antimalware Engine 1.1.7801.0 is released to all Microsoft Security Essentials and Forefront Client Security, Forefront Endpoint Protection, Windows Intune Endpoint Protection customers on 21 September 2011. Signature package 1.115.7.0 is the first that contains this engine.