Synthesis of covert command attackers at the supervisory layer of cyber-physical systems

In this paper, we investigate the problem of command attacker synthesis in cyber–physical systems at the supervisory control layer. The attacker attempts to inflict damage or reach a blocking state, while undetected by the supervisor. Specially, we propose the so-called Command Attack Structure (CAS) to capture attack processes and describe the interaction between the attacker and the supervisory control system. To address the races between attack events and commands or internal events of the control system during the interaction, we propose the conditions of strictly race-free and loosely race-free, which the attacker must adhere to. Moreover, we design pruning algorithms to achieve covert and race-free CASs, and ultimately obtain successful command attackers. Lastly, we also consider combined attacks, which involve multiple attack operations on a single command. Then the combined CAS is designed to model and analyze such scenarios.