Probabilistic Event Graph to Model Safety and Security for Diagnosis Purposes

Diagnosing accidental and malicious events in an industrial control system requires an event model with specific capacities. Most models are dedicated to either safety or security but rarely both. And the latter are developed for objectives other than diagnosis and therefore unfit for this task. In this paper, we propose an event model considering both safety and security events, usable in real-time, with a probabilistic measure of on-going and future events. This model is able to replace alerts in the context of more global scenarios, including with reinforcements or conflicts between safety and security. The model is then used to provide an analysis of some of the security and safety events in the Taum Sauk Hydroelectric Power Station.