A weakest-adversary security metric for network configuration security analysis

A security metric measures or assesses the extent to which a system meets its security objectives. Since meaningful quantitative security metrics are largely unavailable, the security community primarily uses qualitative metrics for security. In this paper, we present a novel quantitative metric for the security of computer networks that is based on an analysis of attack graphs. The metric measures the security strength of a network in terms of the strength of the weakest adversary who can successfully penetrate the network. We present an algorithm that computes the minimal sets of required initial attributes for the weakest adversary to possess in order to successfully compromise a network; given a specific network configuration, set of known exploits, a specific goal state, and an attacker class (represented by a set of all initial attacker attributes). We also demonstrate, by example, that diverse network configurations are not always beneficial for network security in terms of penetrability.