Cyberattacks targeting Industrial Control System (ICS) environments are no longer theoretical. From ransomware incidents shutting down manufacturing plants to intrusions on national infrastructure networks, the risks are real and increasing. ICS security is focused on protecting these control systems — ensuring they operate safely, reliably, and without disruption.
One of the most effective ways to approach ICS security systematically is through the use of security frameworks. Frameworks like NIST CSF, IEC 62443, and ISO 27001 provide structure, consistency, and guidance. They help organisations benchmark their maturity, manage compliance, and implement repeatable security processes across complex industrial environments.
In addition to the established frameworks, a major influence in the European landscape is the NIS2 Directive — which is rapidly transforming how critical industries approach cybersecurity.
Why frameworks matter
In cybersecurity, a framework provides a structured way to manage and reduce risk. It defines the principles, processes, and controls an organisation should use to protect its systems — in this case, its industrial control systems.
In industrial environments, where safety and uptime are critical, having an agreed framework is especially valuable. It helps different teams — from IT and OT to compliance and operations — align around a common language and approach.
Standardising security across industries
ICS security frameworks exist to bring consistency. Without them, each site or department might apply its own security measures, creating gaps and inconsistencies that attackers can exploit. A recognised framework ensures every system, process, and person follows the same baseline practices.
This standardisation also makes it easier to evaluate suppliers, assess third-party risk, and integrate with other organisations in the supply chain — a growing need in industrial sectors.
Supporting compliance and risk management
Frameworks also help organisations meet regulatory and contractual obligations. Whether your business must comply with government regulations, ISO standards, or customer-driven audits, using a recognised framework provides a defensible and transparent way to demonstrate compliance.
Most importantly, frameworks guide organisations in understanding risk — identifying what’s critical, where the weaknesses lie, and how to prioritise investment.
Overview of key ICS security frameworks
There are several frameworks relevant to ICS environments, each serving a slightly different purpose. Three of the most widely used and respected are NIST CSF, IEC 62443, and ISO/IEC 27001. In addition, the NIS2 Directive is now having a major impact on how critical industries approach cybersecurity across the EU.
NIST Cybersecurity Framework (CSF)
The NIST Cybersecurity Framework was developed by the U.S. National Institute of Standards and Technology. Although it originated in critical infrastructure sectors, it’s now used globally across industries of all sizes.
Purpose
To provide a high-level, flexible structure for managing cybersecurity risk.
Structure
The framework is organised around five core functions:
- Identify – Understand assets, systems, data, and risks.
- Protect – Implement safeguards to ensure service delivery.
- Detect – Monitor systems for anomalies and security events.
- Respond – Take action to contain and mitigate incidents.
- Recover – Restore operations and improve resilience post-incident.
Applicability to ICS
NIST CSF is adaptable and scalable. It’s often used by industrial organisations as a management layer — a way to coordinate security activities across both IT and OT environments.
Benefits
- Easy to align with other frameworks
- Supports continuous improvement
- Widely recognised by regulators and customers
Limitations
- High-level guidance — it doesn’t provide detailed technical controls specific to industrial systems.
IEC 62443
The IEC 62443 series, developed by the International Electrotechnical Commission, is the cornerstone standard for industrial automation and control system (IACS) cybersecurity.
Purpose
To provide detailed technical and procedural guidance for securing industrial systems across their entire lifecycle.
Structure
IEC 62443 is a suite of standards divided into four main categories:
- General (IEC 62443-1-x): Terminology, concepts, and models.
- Policies and Procedures (IEC 62443-2-x): Security management systems.
- System Level (IEC 62443-3-x): Technical requirements for systems and networks.
- Component Level (IEC 62443-4-x): Secure product development and component-level requirements.
Applicability to ICS
IEC 62443 is purpose-built for industrial environments. It applies to asset owners, system integrators, and product suppliers, making it a comprehensive reference for everyone involved in OT security.
Benefits
- Directly relevant to industrial automation systems
- Covers both organisational and technical controls
- Widely accepted by regulators and industrial clients
Limitations
- Complex to implement fully — requires specialist understanding
- Best suited to organisations ready for structured, long-term adoption
ISO/IEC 27001
ISO/IEC 27001 is the international standard for Information Security Management Systems (ISMS). It defines how organisations should manage information security risk at a governance and policy level.
Purpose
To establish, implement, maintain, and continually improve an ISMS across the business.
Structure
ISO 27001 is built around the Plan-Do-Check-Act (PDCA) cycle, focusing on continuous improvement through regular review and audit.
Applicability to ICS
While ISO 27001 was originally designed for IT, many organisations use it to provide overarching governance for both IT and OT environments. It complements technical frameworks like IEC 62443 by providing management-level discipline and accountability.
Benefits
- Recognised globally and often required in contracts
- Supports certification and external validation
- Integrates well with business management systems
Limitations
- Less focused on technical controls
- Requires adaptation for industrial contexts
NIS2 Directive
The NIS2 Directive (Network and Information Systems Directive) is a major piece of EU cybersecurity legislation that came into force in 2023, expanding and strengthening the original NIS Directive from 2016. It aims to enhance cybersecurity resilience across critical infrastructure sectors — including manufacturing, energy, and transport — by setting uniform security and incident reporting obligations for both public and private entities.
Purpose
Unlike voluntary frameworks such as NIST or ISO 27001, NIS2 is a mandatory regulatory requirement aimed at ensuring that essential and important entities implement appropriate technical and organisational measures to manage cyber risks.
Structure
NIS2 outlines key obligations for covered organisations:
- Risk management and security measures: Entities must implement policies for risk analysis, incident handling, business continuity, and supply chain security.
- Incident reporting: Organisations must report significant incidents within 24 hours (early warning) and provide detailed reports within 72 hours.
- Governance: Board-level accountability and personal liability for non-compliance.
- Supervision and enforcement: National authorities are granted powers to audit, investigate, and issue substantial fines.
Applicability to ICS
NIS2 has direct implications for industrial control systems (ICS) and OT environments, as many operators of essential services fall under its scope. This includes energy providers, manufacturing companies, water utilities, and other critical infrastructure sectors. It pushes organisations to improve asset visibility, incident response, and network segmentation — areas traditionally weak in OT environments.
Benefits
While compliance may seem demanding, NIS2 provides clear benefits:
- Forces organisations to elevate security maturity and formalise OT risk management.
- Encourages alignment between IT and OT cybersecurity strategies.
- Creates a competitive advantage for compliant organisations when dealing with clients, suppliers, and insurers.
Limitations
NIS2 is prescriptive in outcomes but not in methods — meaning it mandates what must be achieved (e.g. “appropriate measures”), not how to achieve it. Organisations still need to align with frameworks like IEC 62443, NIST CSF, or ISO 27001 to operationalise compliance. Additionally, national interpretations may differ slightly across EU member states, which can complicate implementation for multinational businesses.
Framework comparison
| Framework / Regulation | Primary Focus | Applicability | Strengths | Common Use Case |
| NIST CSF | Cyber risk management | IT + OT | Flexible, widely adopted | Governance alignment |
| IEC 62443 | Industrial automation systems | OT / ICS | Detailed technical controls | Control system security |
| ISO/IEC 27001 | Information Security Management | Enterprise-wide | Governance + certification | ISMS implementation |
| NIS2 Directive | Regulatory and compliance obligations | EU critical infrastructure and manufacturing | Legal accountability, supply chain focus | Compliance alignment and risk governance |
How to choose the right framework
No single framework fits every organisation. The right approach depends on your size, sector, regulatory environment, and maturity level.
Consider your size and sector
Large enterprises with complex supply chains may adopt multiple frameworks simultaneously, using ISO 27001 for governance and IEC 62443 for OT implementation.
SMEs often start with NIST CSF to establish structure before layering on more specific controls as they grow.
Highly regulated sectors (e.g., energy, utilities, and defence) typically require adherence to IEC 62443 due to its direct relevance to control systems.
Assess regulatory requirements
Different jurisdictions and clients may expect compliance with specific standards. For example, in the UK, regulators such as the NCSC and Ofgem increasingly reference both NIST CSF and IEC 62443 when assessing critical infrastructure operators.
Hybrid adoption
In practice, many organisations adopt a hybrid approach — using NIST CSF as the overall framework, ISO 27001 for management processes, and IEC 62443 for technical implementation.
This layered model allows flexibility: management teams can align governance and policy through ISO 27001, while engineering teams apply detailed ICS controls through IEC 62443.
Steps to implement an ICS security framework
Implementing an ICS security framework is a structured process that helps ensure improvements are sustainable, not just reactive.
1. Conduct a gap assessment
Start by understanding your current security posture. Map your existing policies, controls, and processes against the chosen framework. This identifies where you meet the requirements and where there are gaps.
2. Align policies and governance
Develop or update your security policies to align with the framework’s structure. Define roles, responsibilities, and escalation procedures. For ICS environments, this should include coordination between IT, OT, and compliance teams.
3. Build awareness and training
Even the best frameworks fail without engagement. Training operational teams, engineers, and managers ensures that everyone understands their role in maintaining security.
Training should go beyond compliance — helping staff recognise risks, follow secure procedures, and respond appropriately to incidents.
4. Implement controls and monitoring
Introduce or strengthen technical and procedural controls based on the framework’s recommendations. This may include:
- Network segmentation and access control
- Vulnerability management and patching
- Logging and anomaly detection
- Vendor and supply chain assurance
5. Audit and continuous improvement
Frameworks such as ISO 27001 and NIST CSF emphasise the importance of continuous improvement. Regular audits and reviews ensure controls remain effective as technology, operations, and threats evolve.
Establishing performance indicators and governance reporting helps maintain executive visibility and accountability.
Common challenges and practical solutions
Legacy systems
Older industrial systems may not support modern security controls such as encryption or regular patching. The solution is to implement compensating controls, such as network segmentation, monitoring, and strict access control, to reduce exposure.
Lack of OT visibility
Many organisations lack full visibility of their control networks. Passive asset discovery and network monitoring tools can help identify devices and communication patterns without disrupting operations.
Resource limitations
Smaller businesses often face budget or staffing constraints. Prioritisation is key — focus first on critical assets and processes and build capability gradually. Using a framework helps direct limited resources toward the most impactful actions.
Broader compliance and insurance pressure
In parallel with regulatory change, cyber insurance providers are becoming more demanding. Industrial operators seeking or renewing policies are now being asked to demonstrate concrete controls — such as network segmentation, incident response readiness, and vulnerability management — often aligned with frameworks like IEC 62443.
This financial incentive is significant. For many businesses, maintaining insurance coverage depends on being able to evidence a structured and well-managed approach to ICS and OT security.
The combined effect of NIS2 and insurance-driven compliance pressure is a notable acceleration in OT security maturity across Europe. Organisations that once viewed security as a technical add-on are now treating it as a core operational requirement, integrated into governance, procurement, and performance management.
In summary
The combination of structured frameworks and regulatory expectations under NIS2 is driving a new level of maturity in ICS and OT security. At the same time, insurance market scrutiny is making it clear that cybersecurity investment is no longer optional — it’s a prerequisite for resilience, compliance, and insurability.
By aligning with recognised frameworks such as IEC 62443, NIST CSF, ISO 27001, and by addressing the obligations of NIS2, organisations can demonstrate due diligence and strengthen operational reliability in a rapidly evolving threat landscape.
Harpoon Consulting supports industrial organisations in mapping their security posture against these standards, achieving compliance readiness, and building long-term resilience strategies that satisfy both regulatory and insurance expectations. Why not book a free consultation call with one of our team to discuss your current ICS security and start building a stronger, more resilient operation?
