Secure Sensor Design Against Undetected Infiltration: Minimum Impact-Minimum Damage
For operators of cyber-physical systems, this provides a proactive security layer to mitigate damage from stealthy attacks, though it is an incremental extension of existing game-theoretic and sensor design approaches.
The paper proposes a defense mechanism for cyber-physical systems that designs sensor outputs to minimize damage from undetected controller infiltration, rather than detecting attacks. A semi-definite programming algorithm computes optimal linear secure sensor outputs, with numerical analysis showing reduced attack impact.
We propose a new defense mechanism against undetected infiltration into controllers in cyber-physical systems. To this end, we cautiously design the outputs of the sensors that monitor the state of the system. Different from the defense mechanisms that seek to detect infiltration, the proposed approach seeks to minimize the damage of possible attacks before they have been detected. Controller of a cyber-physical system could have been infiltrated into by an undetected attacker at any time of the operation. Disregarding such a possibility and disclosing system's state without caution benefits the attacker in his/her malicious objective. Therefore, secure sensor design can improve the security of cyber-physical systems further when incorporated along with other defense mechanisms. We, specifically, consider a controlled Gauss-Markov process, where the controller could have been infiltrated into at any time within the system's operation. In the sense of game-theoretic hierarchical equilibrium, we provide a semi-definite programming based algorithm to compute the optimal linear secure sensor outputs and analyze the performance for various scenarios numerically.