ISA/IEC 62443 Maturity Explained (In Plain English)

ISA/IEC 62443 is frequently misunderstood as a certification exercise. Organizations produce immaculate documentation while leaving networks flat and access uncontrolled. The standard itself is not the problem. The way it is interpreted often is.

The intent of 62443 is not to prove that nothing can go wrong. It is to reduce the impact when something eventually does.

True maturity means understanding which failures matter most and designing controls that limit blast radius. A less mature organization with honest visibility and enforced controls can be safer than a highly documented organization that does not enforce anything in practice.

Zones and conduits look clean in architecture diagrams. In the real world, exceptions accumulate. Temporary access becomes permanent. Firewall rules lose ownership. Administrative privileges spread because they make work easier.

This does not invalidate the model. It highlights the importance of discipline.