What needs to be checked in the security assessment of a SIS system?
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The expert owners have suggested that, in accordance with the requirements outlined in GB/T2119-2002 on the functional safety of safety instrumented systems in the process industry, a safety check of the safety system should be conducted at each maintenance cycle in order to verify the safety and reliability of the SIS system. During maintenance, it is necessary to carry out system safety checks on the SIS system (other than SIL verification), and it is important to determine what tests need to be performed.
Under the functional safety standards for Safety Instrumented Systems in the process industry as specified in GB/T 21109.1-2022 (note: GB/T 2119-2002 mentioned by you may be a typo; I assume you are referring to GB/T 21109.1-2022), it is crucial to conduct system safety inspections during maintenance periods in order to ensure the safety and reliability of the SIS system. The following are the main inspection and testing items recommended for conducting security checks on SIS systems: Information collection and analysis: Collect relevant information about the SIS system, including its architecture, deployment environment, as well as the hardware and software used. Analyze documents such as the security requirements, threat models, and security policies of the SIS system. Threat modeling and risk assessment: Use threat modeling tools to model threats for SIS systems, identifying potential threats and attack surfaces. Based on the risk assessment method, the severity and impact of threats are determined to provide a basis for setting inspection priorities. System security configuration check: Verify the security configuration of the SIS system to ensure that it is set up in accordance with best practices. Check whether security measures such as network firewalls, access control, and log monitoring have been strengthened. Security function testing: Verify the security functions of the SIS system, such as authentication, authorization, encryption, etc. Test whether the permission management for different types of users is effective, to ensure that the system can properly carry out security functions in various scenarios. Security log analysis: Analyze the security logs of the SIS system to identify abnormal activities and potential intrusion attempts. Ensure that the system can record and monitor security events to support subsequent security reviews and troubleshooting. Vulnerability scanning and penetration testing: Use automated vulnerability scanning tools to conduct a thorough scan of the SIS system in order to identify any potential vulnerabilities and security configuration issues. Conduct penetration testing by simulating the behavior of attackers to identify the weaknesses and vulnerabilities in the SIS system. Backup and recovery testing: Verify the SIS system’s backup strategies and recovery procedures to ensure rapid restoration in the event of failures or data loss. Personnel training and operational procedure inspection: Check the training records of SIS system operators to ensure that they possess the necessary safety knowledge and skills. Review the operating procedures for the SIS system to ensure that operators follow safety best practices. Documents and reports: Prepare detailed safety inspection reports that document the inspection methods, results, and recommendations. The report should include information such as the scope of the inspection, identified security issues, risk assessment, and recommended solutions. Continuous improvement: Based on inspection results and feedback, implement improvement measures to enhance the security and reliability of the SIS system. Regular safety inspections and assessments are carried out to ensure that the SIS system remains in its optimal safe condition at all times.