Optimal Denial-of-Service Attack Scheduling With Energy Constraint Over Packet-Dropping Networks

The recent years have seen a surge of security issues of cyber-physical systems (CPS). In this paper, denial-of-service (DoS) attack scheduling is investigated in depth. Specifically, we consider a system where a remote estimator receives the data packet sent by a sensor over a wireless network at each time instant, and an energy-constrained attacker that cannot launch DoS attacks all the time designs the optimal DoS attack scheduling to maximize the attacking effect on the remote estimation performance. Most of the existing works concerning DoS attacks focus on the ideal scenario in which data packets can be received successfully if there is no DoS attack. To capture the unreliability nature of practical networks, we study the packet-dropping network in which packet dropouts may occur even in the absence of attack. We derive the optimal attack scheduling scheme that maximizes the average expected estimation error, and the one which maximizes the expected terminal estimation error over packet-dropping networks. We also present some countermeasures against DoS attacks, and discuss the optimal defense strategy, and how the optimal attack schedule can serve for more effective and resource-saving countermeasures. We further investigate the optimal attack schedule with multiple sensors. The optimality of the theoretical results is demonstrated by numerical simulations.

I. Introduction

Cyber-physical systems (CPS) usually comprise components that can implement sensing, control, communication, and computation. Their scope of application ranges immensely from transportation systems and power networks to smart buildings and process industry [1], [2] . In CPS, wireless sensors are progressively used as communication components and the alternative to wired sensors in tradition due to their easy deployment and maintenance. This, however, exposes systems to malicious threats. For example, the wheel speed sensors that control Antilock brake systems (ABS), attacked by the ABS spoofer, could cause great damage on safety [3]. More CPS security examples, in which damage on safety and economy losses were led to, can be found in [4]. Researchers have devoted efforts in studying security issues in CPS to avoid large losses due to attacks recently [5]–[7].