Analyzing Origins of Safety and Security Interactions Using Feared Events Trees and Multi-level Model

Existing approaches to analyzing safety and security are often limited to a standalone viewpoint and lack a comprehensive mapping of the propagation of concerns, including unwanted (feared events like faults, failures, hazards, and attacks) and wanted ones (e.g., requirements, properties) and their interplay across different granular system representations. We take this problem to a novel combination of the Fault and Attack Trees (FATs) as Feared Events-Properties Trees (FEPTs) and propose an approach for analyzing safety and security interactions considering a multi-level model. The multi-level model facilitates identifying safety- and security-related feared events and associated properties across different system representation levels, viz. system, sub-system, information, and component. Likewise, FEPT allows modeling and analyzing the inter-dependencies between the feared events and properties and their propagation across these levels. We illustrate the use of this approach in a simple and realistic case of trajectory planning in an intersection point scenario regarding autonomous Connected-Driving Vehicles (CDVs) to address the potential interactions between safety and security.