Safety and Security Interactions Modeling Using the BDMP Formalism: Case Study of a Pipeline

The digitalization of industrial control systems (ICS) raises several security threats that can endanger the safety of the critical infrastructures supervised by such systems. This paper presents an analysis method that enables the identification and ranking of risks leading to a safety issue, regardless of the origin of those risks: accidental or due to malevolence. This method relies on a modeling formalism called BDMP (Boolean logic Driven Markov Processes) that was initially created for safety studies, and then adapted to security. The use of the method is first illustrated on a simple case to show how it can be used to make decisions in a situation where security requirements are in conflict with safety requirements. Then it is applied to a realistic industrial system: a pipeline and its instrumentation and control system in order to highlight possible interactions between safety and security.