Proactive attack detection scheme based on watermarking and moving target defense

In this paper, the attack detection problem is investigated for cyber–physical systems (CPSs) with unknown-but-bounded (UBB) noises. A new hybrid proactive detection scheme is proposed to detect stealthy attacks by combining watermarking and moving target (MT). The designed abnormal detector is based on the residual of the zonotopic observer which can be utilized to estimate states of the system with UBB noises. We prove that the approach proposed in this work does not introduce any performance loss in the absence of attacks. The proposed active detection framework can be employed to detect various types of attacks, such as denial-of-service (DoS), replay and covert attacks. Finally, numerical examples are provided to demonstrate the effectiveness of the proposed methods.