Penetration testing is a well-established practical concept for the identification of potentially exploitable security weaknesses and an important component of a security audit. Providing a holistic security assessment for networks consisting of several hundreds hosts is hardly feasible though without some sort of mechanization. Mitigation, prioritizing counter-measures subject to a given budget, currently lacks a solid theoretical understanding and is hence more art than science. In this work, we propose the first approach for conducting comprehensive what-if analyses in order to reason about mitigation in a conceptually well-founded manner. To evaluate and compare mitigation strategies, we use simulated penetration testing, i.e., automated attack-finding, based on a network model to which a subset of a given set of mitigation actions, e.g., changes to the network topology, system updates, configuration changes etc. is applied. Using Stackelberg planning, we determine optimal combinations that minimize the maximal attacker success (similar to a Stackelberg game), and thus provide a well-founded basis for a holistic mitigation strategy. We show that these Stackelberg planning models can largely be derived from network scan, public vulnerability databases and manual inspection with various degrees of automation and detail, and we simulate mitigation analysis on networks of different size and vulnerability.The first version of this article was published on arXiv under the title 'Simulated Penetration Testing and Mitigation Analysis' [2]. The mitigation analysis formalism was later dubbed 'Stackelberg planning' and discussed in a more general scope in a separate publication [42]. The present version thus concentrates on the application to simulated pentesting. In comparison to the previous version, the algorithmic implementation was removed (it can be found [42]), the presentation was streamlined, typos were fixed and the title changed to reflect the new focus.
Speicher et al.to obtain a good middle ground between accuracy and practicality [12,17] (we discuss this in detail as part of our related work discussion, Section 2).Simulated pentesting has been used to great success, but an important feature was overseen so far. If a model of the network is given, one can reason about possible mitigations without implementing them -namely, by simulating the attacker on a modified model. This allows for analysing and comparing different mitigation strategies in terms of the (hypothetical) network resulting from their application. This problem was recently introduced as Stackelberg planning in the AI community [42]. Algorithmically, the attacker-planning problem now becomes part of a larger what-if planning problem, in which the best mitigation plans are constructed. This min-max notion is similar to a Stackelberg game, which are frequently used in security games [26]. The foundational assumption is that the defender acts first, while the adversary can choose her best response after observing this choice, similar to a market ...