The IEC 62443 standard is the international cybersecurity framework for industrial systems (IACS — Industrial Automation and Control Systems). Developed by the International Society of Automation (ISA) and later standardized by the IEC, it provides a comprehensive framework to secure OT throughout its entire lifecycle — from design to operation.

Structure of the standard:

  • Part 1: General concepts and models (zones, conduits, Defense in Depth)
  • Part 2: Requirements for operators and integrators (policies, procedures, risk management)
  • Part 3: Technical requirements for systems (hardening, monitoring, incident response)
  • Part 4: Requirements for component and product manufacturers (secure development)

Security Levels (SL): IEC 62443 defines 4 security levels (SL 1 to SL 4), corresponding to different attacker profiles — from script kiddies to advanced state-sponsored threats. Each organization must assess its target level based on its business risks.

Why has IEC 62443 become essential?

  • Regulatory reference: cited by NIS2, the CER Directive, and mandated across multiple sectors (energy, nuclear, defense)
  • Common language: facilitates communication among operators, integrators, manufacturers, and auditors
  • Pragmatic approach: acknowledges OT constraints (legacy systems, availability) and proposes a progressive, zone-based implementation

Complying with IEC 62443 means structuring your OT cybersecurity industrially — not with IT “band-aids,” but with a defensible, auditable, and resilient architecture.