1. A method of identifying malicious messages transmitted over a mobile communication network comprising a plurality of mobile terminals, comprising the steps of: equipping said mobile terminals with sentinel modules for monitoring messages passing through the respective mobile terminals, wherein said sentinel modules identify as a candidate malicious message, any message passing through said mobile terminals and failing to comply with a first set of patterns, and issue a corresponding sentinel identification message; providing a set of probe modules for monitoring messages transmitted over said network, wherein said set of probe modules identifies as a candidate malicious message, any message transmitted over said network and failing to comply with a second set of patterns, and issues a corresponding probe identification message; and identifying as a malicious message any message for which identification messages are received from two different types of modules out of said sentinel modules and said set of probe modules.