The critical node game

In this work, we introduce a game-theoretic model that assesses the cyber-security risk of cloud networks and informs security experts on the optimal security strategies. Our approach combines game theory, combinatorial optimization, and cyber-security and aims to minimize the unexpected network disruptions caused by malicious cyber-attacks under uncertainty. Methodologically, we introduce the the critical node game , a simultaneous and non-cooperative attacker-defender game where each player solves a combinatorial optimization problem parametrized in the variables of the other player. Each player simultaneously commits to a defensive (or attacking) strategy with limited knowledge about the choices of their adversary. We provide a realistic model for the critical node game and propose an algorithm to compute its stable solutions, i.e. , its Nash equilibria. Practically, our approach enables security experts to assess the security posture of the cloud network and dynamically adapt the level of cyber-protection deployed on the network. We provide a detailed analysis of a real-world cloud network and demonstrate the efficacy of our approach through extensive computational tests.