Identifying and Detecting Attacks in Industrial Control Systems
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Identifying and Detecting Attacks in Industrial Control Systems Nilufer Tuptuk A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy of University College London. UCL DEPARTMENT OF COMPUTER SCIENCE UCL DEPARTMENT OF SECURITY AND CRIME SCIENCE University College London May 29, 2019 2 I, Nilufer Tuptuk, confirm that the work presented in this thesis is my own. Where information has been derived from other sources, I confirm that this has been indicated in the work. Abstract The integrity of industrial control systems (ICS) found in utilities, oil and natural gas pipelines, manufacturing plants and transportation is critical to national well- being and security. Such systems depend on hundreds of field devices to manage and monitor a physical process. Previously, these devices were specific to ICS but they are now being replaced by general purpose computing technologies and, increasingly, these are being augmented with Internet of Things (IoT) nodes. Whilst there are benefits to this approach in terms of cost and flexibility, it has attracted a wider community of adversaries. These include those with significant domain knowledge, such as those responsible for attacks on Iran’s Nuclear Facil- ities, a Steel Mill in Germany, and Ukraine’s power grid; however, non-specialist attackers are becoming increasingly interested in the physical damage it is possible to cause. At the same time, the approach increases the number and range of vulnera- bilities to which ICS are subject; regrettably, conventional techniques for analysing such a large attack space are inadequate, a cause of major national concern. In this thesis we introduce a generalisable approach based on evolutionary mul- tiobjective algorithms to assist in identifying vulnerabilities in complex heteroge- neous ICS systems. This is both challenging and an area that is currently lack- ing research. Our approach has been to review the security of currently deployed ICS systems, and then to make use of an internationally recognised ICS simulation testbed for experiments, assuming that the attacking community largely lack spe- cific ICS knowledge. Using the simulator, we identified vulnerabilities in individual components and then made use of these to generate attacks. A defence against these attacks in the form of novel intrusion detection systems were developed, based on Abstract 4 a range of machine learning models. Finally, this was further subject to attacks cre- ated using the evolutionary multiobjective algorithms, demonstrating, for the first time, the feasibility of creating sophisticated attacks against a well-protected adver- sary using automated mechanisms. Impact Statement The objective of the research described in this thesis is to develop an approach that can be used to identify vulnerabilities in Industrial Control Systems (ICS). ICS are used to monitor and control many of the national critical services, including energy production, manufacturing plants, chemical processing, financial services, trans- portation and healthcare, to a name but a few. Any failures or disruptions can have severe consequences, from economic damage and lost production, through injury and loss of life, to catastrophic nation-wide effects. The security of these systems is therefore important to national security as well as individual manufacturing enter- prises. As a result, research in this area is of significant interest to policy makers, industry and academia. Given the novelty of Internet-facing ICS to the attacker communities, the po- tential variety of attacks is extensive and unknown. The only way we can begin to understand our exposure to the risk of attack is to conduct practical research studies in which systems and countermeasures are actively attacked in advance of deployment. Recognising that conducting experiments on real systems is not safe and is often not feasible, this research offers an alternative: to create realistic ICS testbeds, and carry out attacks diagnosed to identify vulnerabilities proactively in- stead of waiting for the adversaries to find these vulnerabilities. Our methodology is a new approach to the design of better security. It can be implemented by those that do not have special security knowledge needed to test their systems for vul- nerabilities, in a more conventional manner to help them in making security related decisions. This research has further benefits for academia. The research carried out ap- Impact Statement 6 plies to several academic domains: control engineering, information security and evolutionary computation. Control engineers can use the insight gained from this work to analyse the implications of security on process control, and to design security-aware control algorithms. The detection models we built will interest the information security, machine learning and the fault detection and diagnosis com- munities. The training dataset we have generated in this thesis contains a rich set of attacks; this will be made opensource and will provide a new resource to the research community in this area who are currently reliant on a limited set of exam- ples. We designed a methodology for securing ICS using evolutionary multiobjec- tive optimisation algorithms, and applied this to a domain that is more realistic than has been. Existing studies that make use of adversarial machine learning and evo- lutionary computation tend to focus on simplified examples. ICS security is currently on the agenda of many governmental bodies, stan- dards bodies and business. This research will be beneficial in understanding some of the security threats we are facing, both as the community of attackers changes and as ICS become increasingly Internet facing. Finally, the potential of our ap- proach to handle complexity makes it ideal for application to the IoT systems that underpin Industry 4.0 since these have more complex dynamics and a much larger attack surface. Acknowledgements Firstly, I would like to express my sincere gratitude to my supervisor, Prof. Stephen Hailes for his constant guidance, patience, motivation and support throughout the completion of this thesis. Thank you for always being available, you were always very generous, kind and helpful. Thank you to my second supervisor Prof. David Pym. Thank you to Dr. Bill Langdon and Dr. Hector Menendez for showing interest in my work, and helping me to understand the field of evolutionary computation. I am grateful to Prof. Richard Wortley for his valuable support throughout the years, and giving me the opportunity to do this PhD as part of the UCL Security Science Doctoral Training Centre (SECReT). I would like to also say thank you to administrative staff for their support, and my fellow PhD students at the Department of Security and Crime Science for all the good times and laughs. Thank you to staff and students at the Department of Computer Science for creating a positive and enjoyable work environment. To all my friends: thank you for your friendship, support and patience through- out the years, with special thanks to Rae and Veronika, for always cheering me up and listening to me. I am thankful to my parents, my sisters, my three year and a half old niece Aliya (for reminding me that “a good rabbit never gives up”), and my extended family for their love, support and encouragement, without them none of this would have been possible. Finally, I would like to express my gratitude for the generous funding awarded by the Engineering and Physical Sciences Research Council (EPSRC). The research Acknowledgements 8 presented here was made possible through the grant provided via the EPSRC Secu- rity Science Doctoral Training Centre with reference number EP/G037264/1. The final year of this work was supported by the PETRAS – EPSRC IoT Research Hub. Contents 1 Introduction 23 1.1 Motivation . 24 1.1.1 Attacks against Industrial Control Systems . 27 1.1.2 Security of Industrial Control Systems . 29 1.2 Research Questions . 31 1.3 Thesis Structure and Key Contributions . 32 1.4 List of Publications . 35 2 Background 37 2.1 Terminology . 38 2.2 History of Attacks . 39 2.2.1 Nuclear Power Plants . 40 2.2.2 Petrochemical Plants . 41 2.2.3 Wind Turbines and Solar Systems . 42 2.2.4 Factories . 43 2.2.5 Tunnels . 44 2.2.6 Electricity Industry . 45 2.2.7 Oil and Gas Industry . 46 2.2.8 Water Treatment Systems and Canals . 48 2.2.9 Defence Industry . 49 2.2.10 Traffic Lights . 49 2.2.11 Transportation Systems . 50 2.2.12 Ports . 51 Contents 10 2.3 ICS Attack Taxonomy . 52 2.3.1 Threat Origin . 52 2.3.2 Threats . 54 2.3.3 Attack Vectors . 56 2.3.4 Vulnerabilities . 58 2.3.5 Initial Infection . 60 2.3.6 Attack Impact . 60 2.3.7 Countermeasures . 61 2.4 Summary . 61 3 Literature Review 63 3.1 Detecting Attacks on Industrial Control Systems . 63 3.1.1 Performance Metrics for Intrusion Detection Systems . 63 3.1.2 Intrusion Detection for ICS Network and Hosts . 65 3.1.3 Anomaly Detection in Process Control . 68 3.2 Evolutionary Computation . 73 3.2.1 Evasion and Adversarial Learning . 74 3.2.2 Coevolution Approaches . 78 3.3 Summary . 79 4 Case Study, Threat Model and Methods 80 4.1 Case Study: Tennessee Eastman Process Control Problem . 81 4.1.1 Disturbances . 86 4.2 Threat Model . 89 4.2.1 Denial of Service Attacks . 90 4.2.2 Integrity Attacks . 91 4.2.3 Replay Attacks . 92 4.2.4 Attack Model . 92 4.3 Evolutionary Algorithms and Multiobjective Optimisation . 95 4.3.1 Multiobjective Optimisation . 97 4.3.2 Evolutionary Multiobjective Optimisation Algorithms . 99 Contents 11 4.4 Machine Learning Methods . 108 4.4.1 Decision Trees . 111 4.4.2 Ensemble Learning using Decision Trees . 114 4.4.3 Support Vector Machines . 116 4.4.4 Deep Learning and Deep Neural Network . 125 4.4.5 Recurrent Neural Networks .