A Case Study on Cyber-security Program for the Programmable Logic Controller of Modern NPPs

As instrumentation and control (I and C) systems for modern Nuclear Power Plants (NPPs) have been digitalized to cope with their growing complexity, the cyber-security has become an important issue. To protect the I and C systems adequately from cyber threats, such as Stuxnet that attacked Iran's nuclear facilities, regulations of many countries require a cyber-security program covering all the life cycle phases of the system development, from the concept to the retirement. This paper presents a case study of cyber-security program that has been performed during the development of the programmable logic controller (PLC) for modern NPPs of Korea. In the case study, a cyber-security plan, including technical, management, and operational controls, was established through a security risk assessment. Cyber-security activities, such as development of security functions and periodic inspections, were conducted according to the plan: the security functions were applied to the PLC as the technical controls, and periodic inspections and audits were held to check the security of the development environment, as the management and operational controls. A final penetration test was conducted to inspect all the security problems that had been issued during the development. The case study has shown that the systematic cyber-security program detected and removed the vulnerabilities of the target system, which could not be found otherwise, enhancing the cyber-security of the system