A controller design for mitigation of passive system identification attacks in networked control systems

The literature regarding attacks in Networked Control Systems (NCS) indicates that covert and accurate attacks must be designed based on an accurate knowledge about the model of the attacked system. In this context, the literature on NCS presents the Passive System Identification attack as a metaheuristic-based tool to provide the attacker with the required system models. However, the scientific literature does not report countermeasures to mitigate the identification process performed by such passive metaheuristic-based attack. In this sense, this work proposes the use of a randomly switching controller as a countermeasure for the Passive System Identification attack, in case of failure of other conventional security mechanisms - such as encryption, network segmentation and firewall policies. This novel countermeasure aims to hinder the identification of the controller, so that the model obtained by the attacker is imprecise or ambiguous, in such a way that the attacker hesitates to launch covert or model-dependent attacks against the NCS. The simulation results indicate that this countermeasure is capable to mitigate the mentioned attack at the same time that it performs a satisfactory plant control.