A Survey on Cyber–Physical Systems Security

Cyber–physical systems (CPSs) are new types of intelligent systems that integrate computing, control, and communication technologies, bridging the cyberspace and physical world. These systems enhance the capabilities of our critical infrastructure and are widely used in a variety of safety-critical systems. CPSs are susceptible to cyber attacks due to their vulnerabilities such that their security has become a critical issue. Therefore, it is important to classify and comprehensively investigate this issue. Most of the existing surveys on it are conducted from a single perspective. In this article, we present a comprehensive view of the security of CPSs from three perspectives: 1) the physical domain; 2) the cyber domain; and 3) the cyber–physical domain. In the physical domain, we review some attacks that directly damage the physical components of CPSs such as sensors and discuss corresponding defenses. We also review the attacks that CPSs in the cyber domain may face and study methods to detect and defend against them. In addition, we survey the intelligent attacks faced by CPSs and the corresponding defensive means. In the cyber–physical domain, we provide an overview of attacks that come from the cyber domain and eventually damage the physical parts, and discuss the corresponding detection and defense methods. Finally, we present the challenges and future research directions. Through this in-depth review, we attempt to summarize the current security threats to CPSs and the state-of-the-art security means to provide researchers with a comprehensive overview.

I. Introduction

The rapid development of information technology has put forward higher requirements on the physical world, which entails investigations into cyber–physical systems (CPSs). CPSs are intelligent systems that integrate computing, communication, and control. They form an important part of the Industrial Internet of Things and play an important role in Industry 4.0 [1]. They can sense the world around them and have the ability to adapt to and control the physical world [2]. They closely integrate cyber and physical processes, and exchange data and information in real time. Physical processes are usually carried out by several tiny devices with sensing, computing, or communication capabilities. These physical devices can be identified with physical properties or information sensing devices and are connected to a cyber system, to send data to the computing system [3].