Sequential and Parallel Attack Tree Modelling

Abstract

The intricacy of socio-technical systems requires a careful planning and utilisation of security resources to ensure uninterrupted, secure and reliable services. Even though many studies have been conducted to understand and model the behaviour of a potential attacker, the detection of crucial security vulnerabilities in such a system still provides a substantial challenge for security engineers. The success of a sophisticated attack crucially depends on two factors: the resources and time available to the attacker; and the stepwise execution of interrelated attack steps. This paper presents an extension of dynamic attack tree models by using both, the sequential and parallel behaviour of AND- and OR-gates. Thereby we take great care to allow the modelling of any kind of temporal and stochastic dependencies which might occur in the model. We demonstrate the applicability on several case studies.