The Best 10 OT Cybersecurity Frameworks for Critical Infrastructure

The operational technology (OT) landscape-the digital core that controls our power grids, water treatment plants, manufacturing facilities, and transportation systems-is no longer a closed, air-gapped environment. The convergence of IT and OT, fueled by the Industrial Internet of Things (IIoT) and the drive for greater efficiency, has blurred the lines and exposed previously isolated industrial control systems (ICS) to the volatile world of internet-borne cyber threats.

The stakes in Operational Technology (OT) and Industrial Control System (ICS) cybersecurity are arguably the highest in the entire digital domain. An attack on a financial database is a catastrophe; an attack on a pipeline, a power utility, or a chemical plant is a threat to life, safety, and national security. This elevated risk is why adopting a robust, globally recognized cybersecurity framework isn’t just a best practice-it’s a fundamental requirement for maintaining Critical Infrastructure (CI) resilience.

For OT leaders, security professionals, and compliance officers, the challenge isn’t a lack of guidance, but rather an abundance of standards. This blog post cuts through the noise. Drawing on the latest information, including key updates to major frameworks, we present the 10 best and most influential OT cybersecurity frameworks and standards that organizations must leverage to build a truly resilient cyber-physical ecosystem.

1. The Global Gold Standard: ISA/IEC 62443 Series

The ISA/IEC 62443 series is universally recognized as the definitive international standard

operational resilience. This resilience is what ensures the continuity of essential services, protects public safety, and guarantees the stability of the global economy. The time to build these foundations is now.

started in the IT world, IEC 62443 was born specifically from the needs of the industrial environment, making it the most technically granular and directly applicable standard for securing OT.

Core Philosophy: Zones and Conduits

The foundation of IEC 62443 is its risk-based, defense-in-depth architecture centered on the concept of Zones and Conduits.

• Zones: Groups of logical or physical assets (people, technology, process) that share common security requirements (e.g., a Level 1 PLC Zone, a Level 3 SCADA Zone).
• Conduits: The communication paths between zones, through which all information flow must be controlled and monitored.

This approach mandates that security controls are proportionate to the risk level of the assets within each zone, effectively containing potential breaches.

The Series Breakdown

The standard is a four-part series addressing different roles and lifecycles:

• Part 1 (General): Terminologies, concepts, and models.
• Part 2 (Policies & Procedures): Requirements for Asset Owners and Service Providers. This includes topics like security program management and patch management.
• Part 3 (System Level): Specifies system security requirements, including Security Levels (SLs) (ranging from SL-1 for protection against accidental misuse to SL-4 for protection against sophisticated attacks with extensive resources).
• Part 4 (Component Level): Technical security requirements for control system products (e.g., controllers, embedded devices).

Why it’s a Must-Have: It’s the only standard that holistically addresses security across the entire IACS lifecycle-from product development (suppliers) to system integration (service providers) to daily operations (asset owners). For any multinational industrial operation, IEC 62443 is non-negotiable.

2. The Comprehensive Risk Management Playbook: NIST CSF 2.0 for OT

The National Institute of Standards and Technology (NIST) Cybersecurity Framework (CSF) is the globally adopted, high-level, risk-management framework. The 2024 update to NIST CSF 2.0 significantly broadened its scope beyond U.S. critical infrastructure, emphasizing its applicability to all organizations, including those with substantial OT and ICS environments.

The Six Core Functions (CSF 2.0)

CSF 2.0 expanded from the original five Functions to six, solidifying the framework as a comprehensive management tool:

1. Govern (NEW): Establishes the organization’s cybersecurity risk management strategy, roles, responsibilities, and policy. This is crucial for bridging the IT/OT governance gap and ensuring OT security is an executive-level priority.
2. Identify: Developing an understanding of cybersecurity risk to systems, assets, data, and capabilities. This is where OT asset inventory and risk assessment (using guidelines like NIST SP 800-82r3) are critical.
3. Protect: Developing and implementing safeguards to ensure the delivery of critical services.
4. Detect: Developing and implementing activities to identify the occurrence of a cybersecurity event.
5. Respond: Developing and implementing activities to take action regarding a detected cybersecurity incident.
6. Recover: Developing and implementing activities to restore assets and operations affected by a cybersecurity incident.

Complementary NIST Guidance for OT

The CSF 2.0 is often paired with the more technical and OT-specific guidance in:

• NIST SP 800-82r3, Guide to Operational Technology (OT) Security: A vital resource detailing the unique characteristics of OT, associated threats, and specific security controls tailored for ICS environments.
• NIST SP 800-53: A catalog of security and privacy controls for information systems and organizations.

Why it’s a Must-Have: NIST CSF 2.0 provides the management structure and a common language for leadership to discuss and govern cyber risk. When coupled with SP 800-82r3, it offers a robust, flexible, and internationally respected playbook for integrating OT security into an enterprise risk program.

3. The Threat-Informed Defense: MITRE ATT&CK for ICS

While frameworks like IEC 62443 and NIST CSF tell you what to protect and how to manage your program, the MITRE ATT&CK for ICS framework tells you how adversaries will attack your system. It is a game-changer for moving from a compliance-focused approach to a true threat-informed defense.

Key Features: Tactics and Techniques

ATT&CK for ICS is a knowledge base of adversarial tactics and techniques based on real-world observations of attacks on industrial control systems.

• Tactics: The adversary’s high-level goal (e.g., Inhibit Response Function, Evasion, Impact).
• Techniques: The specific ways an adversary achieves a tactical goal (e.g., Change Control Parameters, Program Download, Exploit Programmable Logic Controller (PLC)).

The framework includes 12 ICS-specific Tactics and dozens of Techniques, detailing the procedures, typical assets targeted (e.g., DCS Controllers, Firewalls, Switches-a key update in the latest v18 release), and corresponding mitigations.

Why it’s a Must-Have: It’s the critical link between generic security controls and real-world threats. It enables organizations to:

• Conduct purple team exercises using known adversary techniques.
• Identify gaps in detection capabilities by mapping existing security monitoring tools against the framework’s techniques.
• Prioritize defenses based on the most likely or impactful attack paths.

4. The U.S. Utility Mandate: NERC Critical Infrastructure Protection (CIP)

For the Bulk Electric System (BES) in North America (U.S., Canada, and Mexico parts of the grid), the NERC CIP standards are not voluntary guidance-they are mandatory, enforceable regulations. Non-compliance can result in significant financial penalties.

Key Focus Areas and Latest Updates (2025)

NERC CIP is a comprehensive set of standards covering various aspects of electric utility security:

• Scope: Defines which assets are considered BES Cyber Systems (BCS) and categorizes them (High, Medium, Low Impact), determining the required level of security rigor. Recent updates (e.g., revisions to CIP-003 and CIP-005) are expanding the scope, subjecting more traditionally “low-impact” assets like substations to stricter controls.
• Security Management: Requires a formal security management program (CIP-003).
• Perimeter and Access: Controls for electronic security perimeters and interactive/non-interactive remote access (CIP-005). Updates are strengthening requirements for Multi-Factor Authentication (MFA) even for low-impact assets.
• Configuration and Vulnerability Management: Strict requirements for configuration control and patch management (CIP-010).
• Supply Chain Risk Management: Rules governing the procurement and vendor risk for BES Cyber Systems (CIP-013).

Why it’s a Must-Have: If your organization operates within the North American BES, NERC CIP is the minimum legal requirement for your OT security program. It is the defining regulatory standard for the power sector.

5. CISA’s Baseline for Resilience: Cross-Sector Cybersecurity Performance Goals (CPGs)

Developed by the U.S. Cybersecurity and Infrastructure Security Agency (CISA), the Cross-Sector Cybersecurity Performance Goals (CPGs) are a relatively new and highly practical framework. They are a voluntary set of priority, high-impact cybersecurity practices that all critical infrastructure entities-regardless of size or sector-should implement to meaningfully reduce risk.

A Focus on Actionable, High-Value Security

The CPGs are explicitly designed to provide a foundational cyber hygiene baseline, particularly for smaller and medium-sized organizations that may be overwhelmed by the complexity of standards like IEC 62443. They are structured to align with the NIST CSF 2.0 functions (Govern, Identify, Protect, Detect, Respond, Recover).

Key OT-Relevant Goals include:

• Maintaining an updated OT/ICS asset inventory.
• Implementing Multi-Factor Authentication (MFA) for all remote and privileged access.
• Enforcing strong network segmentation to separate OT from IT networks.
• Mandating immutable backups for critical operational data to support quick recovery.

Why it’s a Must-Have: The CPGs are arguably the best starting point for any critical infrastructure organization just beginning its OT security journey. They offer a prioritized, cost-effective list of the most impactful security actions, providing a clear roadmap to quickly elevate the cyber posture.

6. The UK’s Standardized Approach: NCSC Cyber Assessment Framework (CAF)

The UK’s National Cyber Security Centre (NCSC) developed the Cyber Assessment Framework (CAF) primarily to provide a systematic and risk-based approach for assessing the cyber resilience of Critical National Infrastructure (CNI) organizations, especially those regulated under the Network and Information Systems (NIS) Regulations.

Four Main Objectives

The CAF is built on four high-level Objectives, which are broken down into 14 security principles:

1. A: Managing Security Risk: Establishing effective governance, risk management, and asset management.
2. B: Protecting Against Cyber Attack: Implementing protective security measures, including policies, access control, and protective monitoring.
3. C: Detecting Security Events: Implementing security monitoring and proactive detection.
4. D: Minimizing the Impact of Security Incidents: Ensuring operational continuity, incident response, and recovery.

Why it’s a Must-Have: For any organization operating critical services in or subject to the regulations of the UK, the CAF is the mandated or de facto standard. It provides clear Indicators of Good Practice (IGPs) that allow organizations to measure and demonstrate an appropriate level of cyber resilience to regulators.

7. The Pipeline Security Blueprint: API Standard 1164

For the oil and natural gas pipeline industry, an industry-specific framework is often required to address unique operational and safety constraints. The American Petroleum Institute (API) Standard 1164, Pipeline Control Systems Cybersecurity, is the definitive guide for this sector.

Focus on SCADA and Safety

The standard focuses on requirements and guidance for managing cyber risk associated with Industrial Automation and Control (IAC) environments, specifically within liquid and gas pipeline systems. Key elements include:

• Risk Assessment: Requires systematic risk assessment to determine the appropriate security measures.
• Security Architecture: Specific guidance on securing SCADA systems, remote terminal units (RTUs), and the communications network.
• Safety Integration: Addresses the crucial interplay between cybersecurity and pipeline safety/integrity, ensuring security measures do not compromise physical safety.

Why it’s a Must-Have: For pipeline operators, API 1164 provides the specific, engineering-focused guidance necessary to comply with broader mandates while addressing the unique security challenges of geographically dispersed, highly critical pipeline control systems.

8. The International Management System: ISO/IEC 27001/27002

While fundamentally an Information Security Management System (ISMS) standard, the ISO/IEC 27001 (Requirements) and ISO/IEC 27002 (Controls) family is highly relevant to OT. It provides the high-level framework for building, implementing, maintaining, and continually improving an organization’s information security posture, which increasingly includes the OT environment.

Applicability to OT

• Management Focus: ISO 27001 is superb for establishing the governance and process around security-defining policy, managing risk appetite, and conducting internal audits. This organizational structure is essential for a mature OT security program.
• Control Mapping: The controls in ISO 27002 can be mapped and tailored to OT. For example, access control controls must be applied to ICS systems, and the disaster recovery controls must be extended to cover the restoration of physical processes.

Why it’s a Must-Have: Many global organizations leverage ISO 27001 for their enterprise-wide security certification. It provides the executive-level assurance and structured management system necessary to ensure OT security processes are consistent, documented, and continually reviewed.

9. The Control Checklist: CIS Critical Security Controls (CIS Controls)

The CIS Critical Security Controls (CIS Controls), published by the Center for Internet Security (CIS), offer a prioritized, consolidated, and prescriptive set of best-practice controls. They are not a full framework but an actionable checklist of high-value defensive actions.

Prioritization for OT

The CIS Controls are broken into three Implementation Groups (IGs) for organizations of different sizes and maturity levels. For OT, the initial focus should be on controls that directly reduce the attack surface:

• Control 1 & 2: Inventory of Enterprise Assets and Software: This is perhaps the single most critical step in OT security-knowing every connected device and piece of software.
• Control 3: Data Protection: Ensuring proper backups and data segregation.
• Control 4: Secure Configuration: Hardening PLCs, HMIs, and other control devices.
• Control 6: Access Control Management: Implementing least privilege access for all OT systems.

Why it’s a Must-Have: The CIS Controls are highly effective for translating abstract policy into concrete, measurable actions. They offer a fast path to establishing a robust OT cyber hygiene program, making them an excellent complement to high-level frameworks like NIST CSF.

10. The Regulatory Driver: Sector-Specific Regulations (SSR)

While not a single framework, the collection of various Sector-Specific Regulations (SSRs) around the world acts as a powerful driver, often mandating the adoption of a formal framework.

Examples of SSRs

• EU NIS 2 Directive: The updated Network and Information Systems Directive significantly strengthens cybersecurity requirements for essential and important entities across the EU, often referencing or aligning with IEC 62443.
• TSA Pipeline Security Guidelines: The U.S. Transportation Security Administration (TSA) issues security directives for pipeline owners and operators, often requiring specific measures for incident response and system testing.
• FDA Regulations (Medical Devices): The U.S. Food and Drug Administration (FDA) has increasingly focused on the cybersecurity of networked medical devices, which are essentially a form of OT/ICS in healthcare.

Why it’s a Must-Have: SSRs often dictate the speed, budget, and priority of an OT security program. They are the regulatory hammer that forces compliance and resource allocation, ensuring that the adoption of frameworks like IEC 62443 or NIST CSF becomes a business imperative rather than just a security aspiration.

Conclusion: The Path Forward to Operational Resilience

The era of isolated operational technology is over. The digital transformation of critical infrastructure, while delivering unprecedented efficiency and innovation, has irrevocably linked physical safety to digital security. As we’ve detailed, navigating this complex landscape requires more than just buying security tools; it demands a strategic, structured approach guided by the world’s most robust cybersecurity frameworks.

The IEC 62443 series provides the technical DNA for securing industrial systems; NIST CSF 2.0 provides the management structure and governance; and MITRE ATT&CK for ICS provides the critical lens of the adversary. These frameworks are not competing standards, but complementary tools in a unified defense strategy.

For leaders in the OT and IT domains, the key takeaway is that security must be viewed as an ongoing operational capability, not a one-time compliance exercise. By adopting a converged framework strategy-leveraging the technical depth of IEC 62443, the managerial oversight of NIST CSF, and the prioritization offered by CISA CPGs-critical infrastructure organizations can move beyond simply mitigating risk to building true operational resilience. This resilience is what ensures the continuity of essential services, protects public safety, and guarantees the stability of the global economy. The time to build these foundations is now.

started in the IT world, IEC 62443 was born specifically from the needs of the industrial environment, making it the most technically granular and directly applicable standard for securing OT.