Secure Networked Control via Software Rejuvenation

Software rejuvenation has been proposed as a prevention mechanism against unanticipated and undetectable attacks on cyber-physical systems. Without needing to implement any detection algorithm, the system is periodically refreshed with a secure and trusted copy of the control software to eliminate any malicious modifications to the run-time code and data that may have corrupted the controller. Previous work has considered using software rejuvenation while being able to disconnect from the network when recovering from dangerous situations. In contrast, we consider using software rejuvenation in cases where a network connection is needed in order for proper recovery to occur. We present an algorithm that satisfies the conditions necessary to ensure safe recovery in such situations where the system must become vulnerable in order to be safe. A procedure for calculating optimal parameters to achieve these conditions is presented, and our approach is illustrated via simulation.