Detectable and Undetectable Network Attack Security of Cyber-physical Systems

Cyber-physical systems (CPSs) integrate computing and communication capabilities to monitor and control physical processes. In order to do so, communication networks are commonly used to connect sensors, actuators, and controllers, implemented, in general, on Programmable Logic Controllers (PLC). The use of communication networks increases the vulnerability of the CPS to attacks that can drive the system to unsafe states. We propose in this paper a defense strategy that prevents damages caused by cyber attacks in the sensor and/or actuator communication channels of supervisory control systems, without changing the behavior of the closed-loop system when it is not attacked. We introduce the definitions of DNA-and UNA-Security, and present necessary and sufficient conditions to verify these properties.