Catch Me If You Learn: Real-Time Attack Detection and Mitigation in Learning Enabled CPS

Increased dependence on networked, software-based control has escalated the vulnerabilities of Cyber-Physical Systems (CPSs). Detection and monitoring components developed leveraging dynamical systems theory are often employed as lightweight security measures for protecting such safety-critical CPSs against false data injection attacks. However, existing approaches do not correlate attack scenarios with parameters of detection systems. In this work, we propose real-time attack detection and mitigation strategies for safety-critical CPSs. A Reinforcement Learning (RL) based framework is presented which adaptively sets the parameters of such detectors based on experience learned from attack scenarios. The detection system is provided with a suitable training environment to learn how to maximize the detection rate while minimizing false alarms. Along with the objective of attack detection, our framework also attempts to preserve system performance by judiciously choosing control actions based on the operating region. Our proposed method i) mathematically establishes a detection strategy for fast and accurate FDI attack detection, ii) correlates the key parameters of the detection system by learning from attack scenarios, and iii) incorporates a real-time attack mitigation strategy that uses formally synthesized fast controllers, thus creating an end-to-end defense against FDI attacks for safety-critical CPSs. We evaluate our proposed method using well-known safety-critical CPS examples.