OT Security Assessment Aligned to IEC 62443
IEC 62443 is the main family of standards for industrial automation and control system security. This ten-question self-assessment borrows its themes (zones, access, patching, monitoring, response, supplier requirements) so an IT manager can see roughly where the plant stands before paying for a formal assessment.
1. How complete is your inventory of OT assets (PLCs, HMIs, switches, engineering stations)?
IEC 62443 style risk work starts with knowing what is on the network.
2. How is the plant network divided into zones and conduits?
3. How are user accounts handled on OT systems?
4. How do you handle patches and firmware updates for OT systems?
IEC 62443-2-3 covers patch management for control system environments.
5. How is remote access by vendors and integrators controlled?
6. What monitoring exists for OT network activity?
7. How ready are you to respond to a cyber incident that stops production?
8. Are backups of OT configurations (PLC programs, HMI projects, switch configs) tested?
9. Has a documented security risk assessment been done for the plant systems?
IEC 62443-3-2 describes risk assessment for system design, including target security levels.
10. Do purchase specifications and supplier contracts include security requirements for new OT equipment?
IEC 62443-4-1 and 4-2 describe secure development and component requirements that buyers can ask for.
How to use this assessment
Answer based on what is true on the plant floor today, not on policy documents. If plants differ, run it once per plant and compare. The score is a percentage of the maximum, mapped to four bands. It is a screening tool: it will not certify anything and it does not replace a formal risk assessment, but it helps decide how much to invest and where to start.
- Ask the plant electrician or controls engineer to answer with you
- Pick the answer that is true for most systems, not the best one
- Re-run after each major project to track progress
What IEC 62443 covers
The series has four groups. General covers terminology and concepts. Policies and procedures covers the security programme of asset owners (62443-2-1), service providers (2-4) and patch management (2-3). System covers risk assessment (3-2) and system security requirements with security levels (3-3). Component covers secure product development (4-1) and technical requirements for components (4-2). Security levels run from 1 to 4, describing protection against increasingly capable attackers. See the reference table in the related tools for a summary of each part.
How to read your band
Exposed and Basic results mean investment in fundamentals pays back fastest: inventory, segmentation, account hygiene and remote access. Developing means you can move toward risk based decisions, such as setting a target security level for each zone. Established means you should collect evidence, test response and consider external assessment if customers in aerospace, defense or automotive supply chains ask for it. A high score on policy with a low score on patching or monitoring usually signals a gap between paper and practice.
Common mistakes
Treating OT like office IT is the most common error: aggressive scanning or untested patching can stop a line. Another is assuming air gaps still exist when ERP, MES and remote support links have quietly bridged them. Teams also confuse compliance with security, collecting documents without changing controls. Finally, many plants forget suppliers: a new CNC or inspection system arrives with default passwords and a vendor modem unless the purchase specification says otherwise.
Frequently Asked Questions
Does this assessment make us IEC 62443 compliant?
No. It is a self-assessment that follows the standard's themes. Formal conformance involves documented processes, defined security levels and often an independent assessor. Use the score to plan, not to claim compliance.
Who should answer the questions?
A mix of IT, controls engineering and plant maintenance. IT knows firewalls and accounts, but only the controls team knows how PLCs and HMIs are really maintained. Disagreements between them are useful findings.
What is a target security level?
In IEC 62443-3-2, a risk assessment sets a target security level (SL-T, from 1 to 4) for each zone. Later you compare it with the capability of components and the achieved level of the system.
Is IEC 62443 mandatory for manufacturers?
Not in itself in most places. It is a voluntary standard, but customers, insurers and regulations such as NIS2 in Europe may point to it or to similar controls. Check your own contractual and legal obligations.
If you want to connect your ERP to shop floor data without adding risk to Level 2 systems, Netray can review the integration design. We build read-only, on-premise options.
Related Tools
Plant Network Segmentation Checklist (Purdue Model)
A 30-item checklist for checking whether your plant network follows Purdue model segmentation, from field devices up to the ERP layer.
Compliance & ContractsIEC 62443 Parts, Security Levels and Requirements Reference
A searchable plain-language guide to the IEC 62443 series: which part covers what, the seven foundational requirements and security levels 1 to 4.
ERP OperationsPlant IT and OT Asset Inventory Worksheet
An editable asset register for servers, network gear, PLCs, HMIs and workstations, with Purdue zone, support dates and replacement budget.
ERP OperationsManufacturing IT Disaster Recovery Plan Template
A fill-in IT disaster recovery plan for a manufacturing site covering ERP, MES, network and plant systems, with roles, priorities and test schedule.
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