چكيده به لاتين
Cyber-physical systems (CPSs) are the integration of computer and communication systems with physical processes. This integration is crucial to improve the efficiency, reliability and resiliency, but, on the other hand, this integration and progress has subjected them to new cyber threats. Unlike cyber systems, successful intrusion to the system is not same as disrupting the physical process under control, but, the goal of attackers is to disrupt a physical process and cause physical damages.
In this thesis, we have proposed a framework for modeling and evaluating the security of cyber-physical systems. To do so, we divide the security modeling process of cyber-physical systems into four parts. In the first part, we focus on the security of control loops, and with considering their control and defensive parameters, we propose an approach for modeling and evaluating the security of them. We show how properties of physical processes including, the speed limitation of valves and the control task scheduling may influence the outcomes of attacks. In the second part, we concentrate on the system and attacker behavior, we capture the discrete and continuous dynamics of cyber-physical systems under attacks. The proposed approach divides the security modeling process of CPSs into two phases of intrusion process modeling and disruption process modeling. In each phase, the game theory paradigm predicts the attacker and the system behaviors. In the third part, an approach for evaluating the direct and indirect impacts of attacks against cyber-physical systems is proposed. In this method, by considering sensor measurements and control signals as the primary target of disturbances, we study how an attack against system parameters can affect the values of other parameters. We can also prioritize the sensor readings and control signals based on their sensitivity to conducted attacks. In the fourth part, we model the intrusion process to predict the attacker’s behavior and propose a new approach for parameterizing the intrusion model. The validation phase of the proposed method is performed by modeling and evaluating the security and the consequence propagation of attacks against two example cyber-physical systems and comparing with other approaches. By using the proposed method, defensive countermeasures can be used more effectively to improve the security of these systems.
