What it means
Human-machine interface security protects operator visibility and control while preserving rapid, reliable access to accurate process information and safe actions.
Why it matters
An HMI compromise can mislead operators, hide alarms, alter commands, disrupt response, or create unsafe decisions even when controllers continue running.
Practical focus
- Harden the platform and application, restrict software and communications, protect accounts, separate administration, and limit command authority.
- Monitor display, alarm, recipe, tag, configuration, and user changes while preserving operator usability and emergency procedures.
- Provide trusted time, backup, failover, alternate views, and recovery paths that are tested with operations.
- Preserve this evidence: Retain the build baseline, application and configuration versions, account and command logs, alarm changes, backups, tests, and recovery exercises.
- Exercise this failure scenario: Operators rely on a manipulated or unavailable display and make a harmful control decision because no trusted alternate view exists.
Common mistakes
- Using the label Human-Machine Interface Security without defining scope, ownership, decision authority, and the exact data, systems, people, or process affected.
- Treating a policy, contract, diagram, dashboard, or tool demonstration as proof that Human-Machine Interface Security operates consistently in production.
- Closing work without retaining the evidence needed to reconstruct the decision and verify the intended control outcome.
- Testing only the normal path and never rehearsing the failure condition: Operators rely on a manipulated or unavailable display and make a harmful control decision because no trusted alternate view exists.
Certification relevance
This subject appears in or supports the following certification bodies of knowledge: