Stealthy targeted local covert attacks on cyber–physical systems

As the usage of networks in control systems becomes ubiquitous, the risk of cyber attacks on cyber–physical systems (CPS) rises significantly. Stealthy attacks belong to the most dangerous cyber attacks, because the adversary may take control of the plant while staying undetected. This paper considers a new attack scenario called targeted local covert attacks that take into account the adversarial objective explicitly and needs fewer disruption resources than standard covert attacks. The explicit conditions are given to show when the local covert attack can achieve its target and simultaneously remain stealthy. A new security index is introduced to evaluate the risk of such attacks on CPS, which is defined as the number of possible distinct targets the adversary may achieve while remaining stealthy. Based on it, an approach is given to choose which channels in the CPS should be secured to enhance cyber security. Experimental results on the three-tank system are provided to demonstrate the stealthiness and target reachability of such attacks. It is also shown how the security index can be utilized.