Water & wastewater | Modelled case study
Expire vendor cryptographic access after water-system maintenance
Does each vendor credential terminate when the approved service task ends?
The modelled organisation
A recognisable problem reaches the operating agenda
This composite scenario follows the Maintenance Manager · Procurement · Cybersecurity functions. It is grounded in the cited problem context but does not identify a real customer.
Operating environment
A water utility operates treatment plants, pumping stations, reservoirs, remote PLC gateways, engineering workstations, telemetry, and vendor maintenance links.
What is at stake
Control and recovery must remain available during facility loss, communications degradation, or supplier intervention without leaving permanent shared access behind.
Situation
Integrators need rapid support access, but reusable certificates and shared VPN accounts remain active across multiple facilities.
Event that forces action
Vendor recertification, support-contract renewal, or discovery of dormant external access.
Concrete system boundary
Systems this case study puts in scope
The model is specific about the operational surfaces that must be discovered, changed, or independently checked.
vendor identities
maintenance VPN or jump host
approved treatment assets
service-task expiry and revocation evidence
Modelled case study walkthrough
How this organisation would use QNSI
The walkthrough connects the real-world problem to a bounded QNSI contribution and an independently reviewable result.
Recognise the operating condition
Integrators need rapid support access, but reusable certificates and shared VPN accounts remain active across multiple facilities.
Frame the decision the owners must make
Does each vendor credential terminate when the approved service task ends?
Apply QNSI to the controlled boundary
Register vendor credentials, certificate chains, service scope, approved dates, facility reach, and responsible sponsor in QNSI.
Leave the team with a concrete result
A maintenance-access ledger with orphaned trust, overbroad facility scope, and revocation confirmation.
Prove the result in the organisation's environment
The utility verifies access-control enforcement, session evidence, break-glass handling, contract clauses, and emergency support.
What useful success looks like
A decision artifact plus proof from the real environment
The model stops at a target result. It becomes an actual case study only when a customer produces and independently validates this evidence in production.
Decision artifact
A maintenance-access ledger with orphaned trust, overbroad facility scope, and revocation confirmation.
Independent validation boundary
The utility verifies access-control enforcement, session evidence, break-glass handling, contract clauses, and emergency support.
Real-world problem grounding
Primary sources behind the model
These sources establish the external requirement, failure mode, or risk context used to model this case. They do not endorse HEOSSI or prove that QNSI completed the scenario.
Customer evidence status
This is modelled, not a customer claim
The organisation is a composite and the result is a target state. This page does not prove a deployment, customer outcome, certification, legal conclusion, regulator endorsement, or completed control.