A Tree-Based Scheme to Assess the Safety and Security for Industrial Control Systems

The growing significance of reliability and security in industrial control systems (ICS) has rendered it essential to investigate the integration of safety and security. However, safety and security were studied and discussed separately in previous studies. Meanwhile, there are some conflicts between safety and security in ICS, making the integration challenging to balance. In this paper, we put forward a scheme to incorporate safety and security in ICS utilizing fault trees and attack defense trees. We present a fault-attack defense tree model to evaluate safety and security. To solve the quantitative analysis issue, we adopted the fuzzy set theory and applied least squares to strengthen the confidence in the assessment outcomes. When conducting an integrated security and assurance assessment, our solution provides effective security countermeasures. In this paper, we prove that the suggested scheme can balance safety and security and properly assess the effectiveness of security countermeasures through experiments and analysis of the Tennessee Eastman system.