Synthesis of Supremal Successful Normal Actuator Attackers on Normal Supervisors

In this paper, we propose and develop an actuator attack model for discrete-event systems. We assume the actuator attacker partially observes the execution of the closed-loop system and eavesdrops the control commands issued by the supervisor. The attacker can modify each control command on a specified subset of attackable events. The goal of the actuator attacker is to remain covert until it can establish a successful attack and lead the attacked closed-loop system into generating certain damaging strings. We then present a characterization for the existence of a successful attacker and prove the existence of the supremal successful attacker, when both the supervisor and the attacker are normal. Finally, we present an algorithm to synthesize the supremal successful normal attackers.