Risk Monitoring and Intrusion Detection for Industrial Control Systems

Doctoral thesis (2018)

Cyber-attacks on critical infrastructure such as electricity, gas, and water distribution, or power plants, are more and more considered to be a relevant and realistic threat to the European society ... [more ▼]

Cyber-attacks on critical infrastructure such as electricity, gas, and water distribution, or power plants, are more and more considered to be a relevant and realistic threat to the European society. Whereas mature solutions like anti-malware applications, intrusion detection systems (IDS) and even intrusion prevention or self-healing systems have been designed for classic computer systems, these techniques have only been partially adapted to the world of Industrial Control Systems (ICS). As a consequence, organisations and nations fall back upon risk management to understand the risks that they are facing. Today's trend is to combine risk management with real-time monitoring to enable prompt reactions in case of attacks. This thesis aims at providing techniques that assist security managers in migrating from a static risk analysis to a real-time and dynamic risk monitoring platform. Risk monitoring encompasses three steps, each being addressed in detail in this thesis: the collection of risk-related information, the reporting of security events, and finally the inclusion of this real-time information into a risk analysis. The first step consists in designing agents that detect incidents in the system. In this thesis, an intrusion detection system is developed to this end, which focuses on an advanced persistent threat (APT) that particularly targets critical infrastructures. The second step copes with the translation of the obtained technical information in more abstract notions of risk, which can then be used in the context of a risk analysis. In the final step, the information collected from the various sources is correlated so as to obtain the risk faced by the entire system. Since industrial environments are characterised by many interdependencies, a dependency model is elaborated which takes dependencies into account when the risk is estimated. [less ▲]

Efficiently computing the likelihoods of cyclically interdependent risk scenarios

in Computers and Security (2017), 64

Quantitative risk assessment provides a holistic view of risk in an organisation, which is, however, often biased by the fact that risk shared by several assets is encoded multiple times in a risk ... [more ▼]

Quantitative risk assessment provides a holistic view of risk in an organisation, which is, however, often biased by the fact that risk shared by several assets is encoded multiple times in a risk analysis. An apparent solution to this issue is to take all dependencies between assets into consideration when building a risk model. However, existing approaches rarely support cyclic dependencies, although assets that mutually rely on each other are encountered in many organisations, notably in critical infrastructures. To the best of our knowledge, no author has provided a provably efficient algorithm (in terms of the execution time) for computing the risk in such an organisation, notwithstanding that some heuristics exist. This paper introduces the dependency-aware root cause (DARC) model, which is able to compute the risk resulting from a collection of root causes using a poly-time randomised algorithm, and concludes with a discussion on real-time risk monitoring, which DARC supports by design. © 2016 Elsevier Ltd [less ▲]

Dynamic Risk Analyses and Dependency-Aware Root Cause Model for Critical Infrastructures

in International Conference on Critical Information Infrastructures Security (2016)

Critical Infrastructures are known for their complexity and the strong interdependencies between the various components. As a result, cascading effects can have devastating consequences, while foreseeing ... [more ▼]

Critical Infrastructures are known for their complexity and the strong interdependencies between the various components. As a result, cascading effects can have devastating consequences, while foreseeing the overall impact of a particular incident is not straight-forward at all and goes beyond performing a simple risk analysis. This work presents a graph-based approach for conducting dynamic risk analyses, which are programmatically generated from a threat model and an inventory of assets. In contrast to traditional risk analyses, they can be kept automatically up-to-date and show the risk currently faced by a system in real-time. The concepts are applied to and validated in the context of the smart grid infrastructure currently being deployed in Luxembourg. [less ▲]