A passivity-based framework for composing attacks on networked control systems

Networked control systems present an inviting target for adversaries seeking to attack physical infrastructure through cyber attacks alone. A diverse set of possible attacks, including node compromise, false data injection, malware propagation, and denial of service have been identified and studied in isolation. Currently, however, there is no framework for composing multiple attacks, mounted by one or more adversaries, and designing a system defense that guarantees stability and allows flexible performance. In this paper, we introduce a passivity framework for modeling and mitigating multiple, interdependent attacks on networked control systems. Under our framework, multiple adversaries are modeled as passive individual blocks, either in parallel or negative feedback interconnections depending on the interdependencies between the attacks, leading to an overall system that is passive and stabilizable. We present two case studies within this framework, namely joint node capture and malware propagation, as well as joint node capture and control channel jamming, and derive a stabilizing network response to the attacks. Our results are illustrated through a numerical study.