Detecting Integrity Attacks on Control Systems using a Moving Target Approach
For control system security, this work provides a detection method against powerful adversaries with full channel access, though it is incremental as it builds on existing moving target concepts.
The paper addresses integrity attacks on control systems where an adversary can read and modify all sensor and actuator channels. It proposes a moving target defense using external states with time-varying dynamics unknown to the attacker, enabling detection of stealthy attacks.
Maintaining the security of control systems in the presence of integrity attacks is a significant challenge. In literature, several possible attacks against control systems have been formulated including replay, false data injection, and zero dynamics attacks. The detection and prevention of these attacks may require the defender to possess a particular subset of trusted communication channels. Alternatively, these attacks can be prevented by keeping the system model secret from the adversary. In this paper, we consider an adversary who has the ability to modify and read all sensor and actuator channels. To thwart this adversary, we introduce external states dependent on the state of the control system, with linear time-varying dynamics unknown to the adversary. We also include sensors to measure these states. The presence of unknown time-varying dynamics is leveraged to detect an adversary who simultaneously aims to identify the system and inject stealthy outputs. Potential attack strategies and bounds on the attacker's performance are provided.