When Malicious Actors Control Your Subsystems: A Systems Engineering Approach to Functional Perseverance

Abstract

Security in modern engineered systems is not merely an added layer of protection but a prerequisite for system functionality. As systems engineers navigate the evolving security landscape, they must prioritize functional perseverance, the ability of a system to maintain operational integrity despite adversarial threats. This article examines a possible method for using system-theoretic process analysis (STPA) and system dynamics (SD) to enhance security-aware system engineering.

The approach shown is inspired by a 1982 paper called “The Byzantine Generals Problem” and is a peer-to-peer voting design that avoids single points of failure. In particular, we propose a system analysis and design approach that would allow the construction of a system capable of using peer-to-peer self-policing to detect an intruder that has already penetrated the security perimeter of the system and corrupted one or more of the subsystems. This article shows how STPA could inform the design of the peer-to-peer voting system and how SD could be used to examine the tradeoff of investments in redundancy versus the expected level of achieved resilience.