Mapping ISA/IEC 62443 to NIST Cybersecurity Framework (CSF)

ISA/IEC 62443 and the NIST Cybersecurity Framework (CSF) are both comprehensive standards designed to enhance the cybersecurity posture of organizations. ISA/IEC 62443 is focused on industrial automation and control systems (IACS), while NIST CSF provides a general framework for managing cybersecurity risk. Mapping ISA/IEC 62443 to NIST CSF allows organizations to harmonize these two standards, leveraging their strengths to ensure robust cybersecurity measures for industrial environments.

This article explores the methodology, examples, and detailed procedural requirements for mapping ISA/IEC 62443 to NIST CSF.

ISA/IEC 62443

ISA/IEC 62443 is a series of standards, technical reports, and related information that define procedures for implementing electronically secure industrial automation and control systems (IACS). It covers multiple aspects of cybersecurity, including system requirements, policies, and technical controls.

NIST Cybersecurity Framework (CSF)

The NIST CSF is a voluntary framework consisting of standards, guidelines, and best practices to manage cybersecurity-related risks. It is structured around five core functions: Identify, Protect, Detect, Respond, and Recover.

Purpose of Mapping

Mapping ISA/IEC 62443 to NIST CSF helps organizations:

• Integrate specific industrial control system (ICS) security practices with a broader cybersecurity risk management framework.
• Streamline compliance with both standards.
• Enhance the security and resilience of their IACS environments.

Mapping Methodology

Step 1: Understand the Structures

1. ISA/IEC 62443:

   • Parts: Multiple parts addressing different aspects, such as policies, system requirements, component requirements, and lifecycle requirements.
   • Key Parts:
     • ISA/IEC 62443-2-1: Establishing an IACS security program.
     • ISA/IEC 62443-3-3: System security requirements and security levels.
     • ISA/IEC 62443-4-2: Technical security requirements for IACS components.

2. NIST CSF:

   • Core Functions: Identify, Protect, Detect, Respond, and Recover.
   • Categories and Subcategories: Detailed activities and outcomes within each function.
   • Informative References: Guidelines and practices mapped to each subcategory.

Step 2: Identify Common Elements

Identify overlapping areas by analyzing the objectives of each standard. Both frameworks emphasize risk management, access control, threat detection, and incident response.

Step 3: Map Specific Controls

Match ISA/IEC 62443 requirements to corresponding NIST CSF categories and subcategories. Analyze the objectives and procedures required for each control to ensure accurate mapping.

Step 4: Create a Crosswalk Table

Crosswalk Table: Mapping ISA/IEC 62443 to NIST CSF

The following crosswalk table maps specific requirements from ISA/IEC 62443 to corresponding categories and subcategories in the NIST Cybersecurity Framework (CSF). This table helps ensure that all necessary controls and procedures are accounted for when integrating the two standards.

Mapping Examples

Example 1: ISA/IEC 62443-3-3 SR 1.1 – Human User Identification and Authentication

ISA/IEC 62443-3-3 Requirement:

• SR 1.1: The system shall provide identification and authentication mechanisms for human users.

NIST CSF Mapping:

NIST CSF Category: Protect (PR)

• Function: Protect (PR)
  • Category: PR.AC - Identity Management, Authentication, and Access Control
    • Subcategory: PR.AC-1: Identities and credentials are issued, managed, verified, revoked, and audited for authorized devices, users, and processes.
      • Procedural Requirements:
        • Implement mechanisms to uniquely identify and authenticate users.
        • Issue and manage user credentials securely.
        • Regularly verify and audit user identities and access rights.
        • Implement processes for revoking access when no longer needed.

Example 2: ISA/IEC 62443-2-1 SR 2.6 – Security Monitoring

ISA/IEC 62443-2-1 Requirement:

• SR 2.6: The IACS environment shall be monitored to detect security events.

NIST CSF Mapping:

NIST CSF Category: Detect (DE)

• Function: Detect (DE)
  • Category: DE.CM - Security Continuous Monitoring
    • Subcategory: DE.CM-1: The network is monitored to detect potential cybersecurity events.
      • Procedural Requirements:
        • Establish continuous monitoring of the IACS network.
        • Implement tools and techniques to detect security events in real-time.
        • Regularly review and analyze monitoring data.
        • Maintain logs and records of detected events for further analysis.

Example 3: ISA/IEC 62443-4-2 CR 3.5 – Access Control

ISA/IEC 62443-4-2 Requirement:

• CR 3.5: The IACS components shall support logical access control to restrict access to authorized entities.

NIST CSF Mapping:

NIST CSF Category: Protect (PR)

• Function: Protect (PR)
  • Category: PR.AC - Identity Management, Authentication, and Access Control
    • Subcategory: PR.AC-3: Remote access is managed.
      • Procedural Requirements:
        • Implement logical access controls on IACS components.
        • Ensure that access control mechanisms are in place to restrict remote access to authorized users only.
        • Regularly review and update access control policies and mechanisms.

Detailed Procedural Requirements

Implementing Human User Identification and Authentication (SR 1.1 / PR.AC-1)

1. Identify and Authenticate Users:

   • Implement unique identification methods (e.g., user IDs, biometric data).
   • Use strong authentication mechanisms (e.g., passwords, multi-factor authentication).

2. Manage User Credentials:

   • Securely issue and manage credentials.
   • Implement policies for password complexity and expiration.

3. Verify and Audit:

   • Regularly review user access rights.
   • Conduct periodic audits to ensure compliance with access control policies.

4. Revoke Access:

   • Implement procedures for promptly revoking access when no longer needed.
   • Ensure that all access points (physical and logical) are updated when access is revoked.

Establishing Security Monitoring (SR 2.6 / DE.CM-1)

1. Continuous Monitoring:

   • Deploy monitoring tools to capture network activity and detect anomalies.
   • Implement logging mechanisms to record events.

2. Real-Time Detection:

   • Use intrusion detection systems (IDS) and security information and event management (SIEM) systems.
   • Monitor for specific indicators of compromise (IoCs).

3. Review and Analysis:

   • Regularly analyze monitoring data for signs of security events.
   • Correlate data from different sources for comprehensive analysis.

4. Maintain Logs:

   • Keep detailed logs of all detected events.
   • Ensure logs are protected from tampering and are accessible for forensic analysis.

Managing Access Control (CR 3.5 / PR.AC-3)

1. Implement Logical Access Control:

   • Define and enforce access control policies.
   • Ensure access is granted based on the principle of least privilege.

2. Manage Remote Access:

   • Implement secure remote access solutions (e.g., VPNs, secure tunnels).
   • Monitor and control remote access sessions.

3. Review and Update Policies:

   • Regularly review access control policies to ensure they remain effective.
   • Update policies based on changing requirements and threat landscape.

Mapping ISA/IEC 62443 to NIST CSF provides a structured approach to integrating industrial control system security with broader cybersecurity risk management. By following the outlined methodology and implementing the detailed procedural requirements, organizations can enhance their cybersecurity posture, streamline compliance efforts, and ensure robust protection for their industrial environments.

This article provides a practical guide to understanding and applying the mapping between ISA/IEC 62443 and NIST CSF, offering examples and detailed procedural steps to aid organizations in this endeavor.