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.

I. Introduction

Recently, cyber-physical systems (CPS) have drawn much research interest within the discrete-event systems and formal methods communities [1]–[9]. Due to the prevalence of cyber-physical systems in modern society and the catastrophic consequences that could happen after these systems get attacked [10], [11], it is important to design resilient control mechanisms against adversarial attacks. The first step towards this goal is to understand when adversarial attacks can succeed.