Cyber-physical security of a chemical plant

The increasing number of cyber attacks on industries demands immediate attention for providing more secure mechanisms to safeguard industries and minimize risks. A supervisory control and data acquisition (SCADA) system employing the distributed networks of sensors and actuators that interact with the physical environment is vulnerable to attacks that target the interface between the cyber and physical subsystems. These cyber attacks are typically malicious actions that cause undesired results in the cyber physical world, for example, the Stuxnet attack that targeted Iran\u27s nuclear centrifuges. An attack that hijacks the sensors in an attempt to provide false readings to the controller can be used to feign normal system operation for the control system, while the attacker can hijack the actuators to send the system beyond its safety range. Cyber physical systems (CPS) being used in industries such as oil and gas, chemical process plants and the like are termed Industrial Control Systems (ICS). Control system security is aimed at preventing intentional or unintentional interference with the proper operation of ICS. This thesis proposes a process-aware approach with the use of invariant equations based on the physical and chemical properties of the process and a Multiple Security Domain Nondeducibility (MSDND) framework to detect when a sensor signal is being maliciously manipulated. We have taken a benzene production plant as case study to illustrate our approach and its effectiveness in determining the state of the system. A system without any MSDND secure information flows between the CPS and cyber monitors has fewer weaknesses that can be exploited --Abstract, page iii