A system, method and program product for defending against man in the middle (MITM) attacks directed at a target server. A system is provided that includes an activity recording system that records an incoming IP address, userid, and time of each session occurring with the target server; an activity analysis system that identifies suspect IP addresses by determining if an unacceptable number of sessions are occurring from a single incoming IP address during a predefined time period; and a countermeasure system for taking action against suspect IP addresses.