Existence Theorems and Approximation Algorithms for Generalized Network Security Games

Aspnes et al [2] introduced an innovative game for modeling the containment of the spread of viruses and worms (security breaches) in a network. In this model, nodes choose to install anti-virus software or not on an individual basis while the viruses or worms start from a node chosen uniformly at random and spread along paths consisting of insecure nodes. They showed the surprising result that a pure Nash Equilibrium always exists when all nodes have identical installation costs and identical infection costs. In this paper we present a substantial generalization of the model of [2] that allows for arbitrary security and infection costs, and arbitrary distributions for the starting point of the attack. More significantly, our model GNS(d) incorporates a network locality parameter d which represents a hop-limit on the spread of infection as accounted for in the strategic decisions, due to either the intrinsic nature of the infection or the extent of neighborhood information that is available to a node. We determine that the network locality parameter plays a key role in the existence of pure Nash equilibria (NE): local (d = 1) and global games (d = ∞) have pure NE, while for GNS(d) games with 1