DIDoS: Disturbance-induced Denial-of-service Attack in Networked Cyber-physical Systems

Abstract

Event-triggered control (ETC) in a cyber-physical system (CPS) is an efficient aperiodic control strategy that generates control packets only when a control-triggering condition is satisfied. However, the CPS with ETC introduces a new point of vulnerability. A well-designed disturbance signal can unnecessarily trigger control events and the resulting excessive packet exchanges can destabilize the physical systems due to network saturation. In this paper, we propose a novel CPS attack vector entitled the disturbance-induced denial of service (DIDoS) attack, which has the following key characteristics: DIDoS cannot be mitigated by a conventional network security method such as a firewall. Unlike most cyber-physical attacks, DIDoS does not require knowledge of physical system dynamics. Under DIDoS, a disturbance signal into a single physical system can saturate the whole network and destabilize all the physical systems connected to the network. We study the relationship between the network delay and the stability of physical systems under DIDoS. We derive a stability condition under a time-varying network delay and quantitatively describe network saturation under DIDoS with an IEEE 802.11 wireless network model. Our simulation results show that DIDoS can saturate the network and destabilize all the physical systems.