Abstract | Cyber-Physical Systems (CPS) suffer from extendable vulnerabilities due to the convergence of the physical world with the cyber world, which makes it victim to a number of sophisticated cyber-attacks. The motives behind such attacks range from criminal enterprises to military, economic, espionage, political, and terrorism-related activities. Many governments are more concerned than ever with securing their critical infrastructure. One of the effective means of detecting threats and securing their infrastructure is the use of Intrusion Detection Systems (IDS) and Intrusion Prevention Systems (IPS). A number of studies have been conducted and proposed to assess the efficacy and effectiveness of IDS through the use of self-learning techniques, especially in the Industrial Control Systems (ICS) era. This paper investigates and analyzes the utilization of IDS systems and their proposed solutions used to enhance the effectiveness of such systems for CPS. The targeted data extraction was from 2011 to 2021 from five selected sources: IEEE, ACM, Springer, Wiley, and ScienceDirect. After applying the inclusion and exclusion criteria, 20 primary studies were selected from a total of 51 studies in the field of threat detection in CPS, ICS, SCADA systems, and the IoT. The outcome revealed the trends in recent research in this area and identified essential techniques to improve detection performance, accuracy, reliability, and robustness. In addition, this study also identified the most vulnerable target layer for cyber-attacks in CPS. Various challenges, opportunities, and solutions were identified. The findings can help scholars in the field learn about how machine learning (ML) methods are used in intrusion detection systems. As a future direction, more research should explore the benefits of ML to safeguard cyber-physical systems. |