Detecting and countering malicious code in enterprise networks

A system and method for detecting and countering malicious code in an enterprise network are provided. A pattern recognition processor monitors local operations on a plurality of local machines connected through an enterprise network, to detect irregular local behavior patterns. An alert may be generated after an irregularity in behavior pattern on a local machine is detected. Irregular behavior alerts from a plurality of local machines are analyzed. If similar alerts are received from at least a threshold number of local machines over a corresponding period of time, one or more countermeasure operations are selected based on the analysis of the irregular behavior alerts. The selected countermeasure operations are communicated to the local machines and performed by the local machines.