A Sequential Game of Defense and Attack on an Interdependent System of Systems

Abstract

This research studies the defense strategy of an interdependent system in the face of rational attacks. We propose a sequential game between an attacker and a defender on an interdependent system of systems (SoS) to explore the effect of interdependency on the optimal defense strategy. An algorithm of backward induction isdeveloped to obtain the Nash equilibrium of the game.The attacker is the first mover as he applies an attack strategy on constituent systems that maximize his utility. The defender observes and responds by a defense strategy that maximizes her utility. Both players’ utilities are evaluated as the difference between a player’s reward due to SoS functionality (dysfunctionality) and the cost of the action. The sensitivity analysis compares the effects of different parameters on the attacker’s and defender’s strategies such as the effectiveness of defense (attack), the unit cost of defense (attack) and the interdependency level on constituent systems.