They let teams analyse access relationships outside the live OT environment. By loading snapshots into a model, practitioners can find redundant, orphaned and mismatched access paths while leaving the control system untouched. That makes access review possible in environments where direct integration would be too risky.
How digital twins make OT access review workable
Digital twins let reviewers examine access relationships in a replica of the OT environment instead of touching the live control system. That matters because OT review often has to balance security with availability, safety and change intolerance. The twin gives teams a controlled place to inspect accounts, roles, dependencies and inherited permissions before they decide what should remain.
A good twin also turns access review from a one-off spreadsheet exercise into a model of actual operating relationships. It is especially useful when access is spread across engineering workstations, HMIs, vendor paths and shared operational accounts. In that setting, the value is not simulation for its own sake, but the ability to see which access paths still make sense when mapped against current plant design and operating practice.
For readers comparing OT review methods, the key distinction is that the twin supports analysis without forcing direct integration into fragile systems. That makes it easier to review access at scale, isolate review activity from production risk, and validate whether a permission is still justified by process ownership, maintenance need or vendor support requirements. For OT-specific identity and access patterns, the OT and ICS Identity and Access Guide is the closest operational companion, and the broader IAM and IGA Basics resource helps frame how access review fits into governance.
What a twin can reveal that live OT review usually cannot
In live OT, many organisations avoid broad discovery or intrusive checks because timing, vendor support windows and legacy protocols make the environment unforgiving. A digital twin gives you a way to compare intended access with effective access, including cases where a path exists only because it was inherited long ago or copied from a previous project. That is where redundant, orphaned and mismatched access becomes easier to spot.
The strongest use case is not just visibility, but relationship testing. A twin can show whether a maintenance account still aligns to an active asset, whether a vendor route is still required for a specific line or site, and whether a privileged pathway is broader than the job function warrants. The review result is stronger when the model is tied to current asset inventory and role ownership, not just to a static access list. The Access Reviews and Certification Guide is useful here because it focuses on removing access, reducing reviewer fatigue and making certification decisions more defensible.
Digital twins are also helpful when access is shaped by lifecycle drift. OT access tends to accumulate through projects, outages, upgrades and emergency support. A twin can expose permissions that survived the original need, even when the system, vendor relationship or operational process changed. That is why the NHI Lifecycle Management Guide is relevant as a lifecycle lens, even though the operational context here is OT rather than generic enterprise IT.
How to use the model without creating a false sense of assurance
A twin is only as good as the snapshot quality, asset mapping and governance behind it. If the model is stale, partial or built from incomplete source data, it can hide the very access paths you are trying to find. Teams should treat the twin as a review instrument, not as proof that access is safe. The model should be reconciled to authoritative asset and entitlement sources before decisions are made.
It also helps to review OT access by relationship class, not just by account name. Shared accounts, vendor remote access, break-glass paths and inherited admin rights each behave differently, so they should not all be judged with the same rule. Where segregation of duties matters, the twin can surface conflicting combinations that would be hard to spot in raw account exports. For that reason, the Segregation of Duties (SoD) Guide is a good companion when reviews need to distinguish legitimate operational support from toxic privilege overlap.
When organisations want a more complete operational view, the Identity Visibility and Intelligence Platforms (IVIP) Guide reinforces the same principle: review decisions improve when teams can see identity relationships, access drift and hidden dependencies in one place. That does not replace OT judgment, but it makes the review more evidence-led.
Risk and Threat Considerations
Digital twins reduce review risk, but they can also mask it if teams treat the model as complete when it is only approximate. The main danger is missing a permission that still reaches a production asset, especially through vendor access, shared accounts or stale administrative pathways. In OT, that kind of miss can preserve unnecessary exposure even when the live system itself was never directly touched during review.
Failure mechanism: The twin is built from incomplete or out-of-date entitlement, asset or network data, so the review validates a clean model while the real environment still contains excess or orphaned access paths.
Impact: Unnecessary OT access remains in place, privileged paths stay broader than intended, and an attacker or careless insider can exploit the gap between the model and the production reality.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
NIST SP 800-53 Rev 5 and CIS Controls v8 set the technical controls, while ISO/IEC 27001:2022 defines the regulatory obligations.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST SP 800-53 Rev 5 | AC-2 — Account Management | OT access review depends on identifying and reviewing active accounts and access paths. |
| AC-6 — Least Privilege | The question centers on redundant and mismatched access paths that should be reduced. | |
| AU-6 — Audit Record Review, Analysis, and Reporting | A twin is useful when review decisions rely on evidence from logs and entitlement data. | |
| Recommendation — Review OT accounts regularly and remove accounts that no longer have a justified operational need. Limit OT access to the minimum permissions required for the current operational role. Correlate OT access findings with logs and review evidence before certifying access. | ||
| ISO/IEC 27001:2022 | A.5.18 — Access rights | OT access review is fundamentally about reviewing and adjusting access rights over time. |
| A.8.5 — Secure authentication | OT access models often include accounts and credentials that must be controlled during review. | |
| Recommendation — Review and revalidate OT access rights at planned intervals and after role or vendor changes. Verify OT accounts and credentials remain bound to approved operational use. | ||
| CIS Controls v8 | CIS-5 — Account Management | The subject concerns finding and removing stale or excessive access in OT environments. |
| Recommendation — Inventory OT accounts and disable those that are orphaned, shared without approval, or no longer required. | ||
Practitioner Guidance
What to verify: Confirm that the twin is reconciled to current OT asset ownership, active vendor relationships and the latest entitlement exports before using it for certification. If the model cannot show where a permission maps in the live estate, treat the review result as provisional.
Decision rule: If a permission exists only because of historical convenience, emergency support or copied configuration, require an explicit business owner to re-justify it rather than carrying it forward by default. In OT, “still present” is not the same as “still needed.”
What good looks like: Reviewers can explain why each remaining access path exists, which asset or function it protects, and what operational need would fail if it were removed. The objective is a small set of justified exceptions, not a tidy model with unresolved risk hidden underneath.
Practitioner takeaway: Digital twins are most valuable when they make OT access review safer to perform and easier to defend, but the review is only as strong as the snapshot quality and governance feeding the model.
Related resources from NHI Mgmt Group
Deepen Your Knowledge
Free weekly newsletter
Subscribe to the NHI & AI Identity Journal
The latest on NHI and Agentic AI security – articles, research, breaches, news and events every week.
Bonus 33% off our NHI Course when you subscribe.
Reviewed and updated by the NHIMG editorial team on October 10, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org