Recovery-Guaranteed Sensor Attack Detection for Cyber-Physical Systems

Sensor attacks on Cyber-Physical Systems (CPS) can cause substantial damage in the physical world, which motivates two major threads of defense works including attack detection and attack recovery. The former aims to identify whether any sensors are compromised while the latter seeks to restore a system to safety once an attack is detected. Although either thread has drawn many efforts, how to coordinate the detection and recovery has been barely studied. Overlooking the coordination, existing works may result in ineffective and even failed defense. For example, if a detector raises an alarm too late, there may not be enough time for a system to recover but reach the unsafe region anyway, even though the detection result is accurate. By contrast, raising an alarm earlier allows more time for recovery, but may come with more false positives and thus unnecessarily trigger the recovery. To fill this gap, we aim to co-design attack detection and recovery, and propose a novel recovery-guaranteed sensor attack detection framework. The framework dynamically adjusts the detection sensitivity and authenticates state estimates at run time to guarantee timely and safe recovery once an attack is detected. The detection will always reserve sufficient time for the recovery while minimizing unnecessary activation of recovery. We conduct extensive simulations and real-world testbed experiments to show the efficiency of our solution.