Robust Covert Attack Strategies and Their Detection for Switched Cyber-Physical Systems

In this paper, first, a robust covert attack is designed for switched cyber-physical systems with synchronous switching from the attacker-viewpoint in which the attacker makes the system follow their specified reference signal while it remains stealthy in the monitoring system. This attack is defined in the form of H-infinity control problem such that the objectives of the attacker will be achieved. Next, as a defender, a novel detection method will be presented that can detect covert attacks in the switched system. In the proposed method, we do not need any secure channel and even in the case that the attacker can find the model of the auxiliary system and injects another signal on the corresponding communicated information, the cyber-attack can be detected. The only protected information in the proposed method is the considered delay in the mode information of the auxiliary system that needs to be exactly estimated by the attacker to have a completely stealthy attack. Simulation results demonstrate and illustrate the significant performance and capabilities of the proposed method.