IEC 62443-3-2:2020 Security for industrial automation and control systems

Part 3-2: Security risk assessment for system design

IEC/TS 62443-3-2:2020, titled "Security for industrial automation and control systems - Part 3-2: Security risk assessment and system design for IACS," provides a comprehensive framework for conducting security risk assessments and designing secure industrial automation and control systems (IACS). The document outlines how asset owners, system integrators, and other stakeholders can systematically evaluate security risks within IACS environments and implement security measures tailored to mitigate those risks.

The focus is on defining a structured approach for identifying potential security threats, assessing vulnerabilities, and designing security solutions that protect against those threats while maintaining operational continuity. The standard complements the broader IEC 62443 series by providing guidance on how to approach the security design and risk assessment process.

Key Objectives:

• Risk Assessment Process: Establish a formalized process for conducting security risk assessments for IACS, ensuring that vulnerabilities and potential threats are identified and prioritized based on their potential impact on operations.

• Zone and Conduit Approach: The document promotes the concept of dividing the IACS environment into zones (areas of similar risk) and conduits (connections between zones) to better manage and segment security controls.

• Security Level Targeting: Based on risk assessments, the standard helps define target security levels (SLs) for different parts of the system, specifying the necessary security controls required to meet those levels.

Key Areas of Focus

1. Risk Assessment Methodology:

2. The document provides a step-by-step approach to identifying and evaluating security risks within the IACS, accounting for potential threats, vulnerabilities, and the impact on operations.

3. This methodology is essential for determining the likelihood and consequences of a security incident, which helps in prioritizing security efforts.

4. Zone and Conduit Model:

5. Zones: Refers to grouping system components that have similar security requirements and risk levels (e.g., manufacturing control zones, safety-critical zones).

6. Conduits: Represents communication pathways between zones, which must be secured to prevent the spread of attacks between different parts of the IACS.

7. This model helps in organizing security controls and isolating critical assets from less critical ones.

8. Determining Security Levels (SLs):

9. The document introduces the concept of Security Levels (SL 1 to SL 4), which define the degree of protection required based on the assessed risk and potential impact.

10. Security levels are assigned to zones and conduits to ensure they meet the specific security needs based on their criticality.

11. System Design Based on Risk:

12. Once the risk assessment is complete and security levels are defined, the standard provides guidance on designing security solutions that address the identified risks.

13. This includes choosing appropriate security controls such as access control, monitoring, encryption, and network segmentation based on the defined security levels.

14. Continuous Risk Management:

15. Security risks evolve over time, so the standard emphasizes the need for continuous monitoring, periodic reviews, and updates to the risk assessment and security design.

16. It supports a lifecycle approach where security measures are regularly evaluated and adjusted to respond to new threats or changes in the system.

Key Takeaways

• Structured Risk Assessment Process: IEC/TS 62443-3-2 provides a formal, systematic process for conducting security risk assessments in IACS environments. It helps asset owners and integrators understand how to identify and prioritize risks.

• Zone and Conduit Model: The concept of dividing an IACS environment into zones (groups of similar risk) and conduits (secure communication pathways) is a key strategy for organizing security measures. It simplifies security management by grouping assets based on their risk profile and ensuring secure connections between zones.

• Security Levels: By defining security levels (SL 1 to SL 4), stakeholders can design security controls that are appropriate for each zone's level of risk and criticality. This ensures resources are allocated efficiently and high-risk areas receive the most robust protection.

• Tailored Security Design: The standard guides stakeholders through designing a security architecture that fits their specific risk profile. This helps balance security with operational efficiency, ensuring the security measures do not disrupt normal operations.

• Lifecycle Security: Security is not a one-time task. The standard stresses the need for continuous risk assessment and security management throughout the lifecycle of the IACS, adapting to new threats as they emerge.

In Summary:

IEC/TS 62443-3-2 provides essential guidance for conducting security risk assessments and designing secure industrial automation and control systems. It introduces the zone and conduit model to help segment systems based on risk, defines security levels to ensure appropriate protection measures, and emphasizes a continuous approach to managing security risks. The key takeaway is that organizations can systematically assess and mitigate security risks in IACS environments while maintaining operational effectiveness.