How should security teams govern access reviews in complex Active Directory environments with nested groups and multiple domains?

Why This Matters for Security Teams

Nested groups, inherited permissions, and multiple domains make access reviews in Active Directory easy to misunderstand and hard to defend. A reviewer may approve a harmless-looking group without realising it grants access through transitive membership, foreign security principals, or a domain trust. That is why access governance has to move beyond “who is in the group” and ask “what effective access does this identity actually receive?”

This is not just an audit problem. It is an accountability problem, because evidence must show the source of entitlement, the approval path, and the owner who can remediate it. NHI Management Group’s Ultimate Guide to NHIs and Regulatory and Audit Perspectives both reinforce the same practical point: governance fails when inventories are not tied to ownership and lifecycle controls. The control objective should be repeatable evidence, not a one-time cleanup.

Current guidance from NIST Cybersecurity Framework 2.0 and the OWASP Non-Human Identity Top 10 supports this approach: establish asset and identity visibility first, then govern entitlement risk with consistent review criteria. In practice, many security teams discover excessive access only after a cross-domain trust or legacy group nesting has already been used to reach sensitive systems.

How It Works in Practice

Effective reviews begin by flattening the effective access graph into a reviewable dataset. That means resolving direct members, nested groups, domain-local and universal groups, foreign security principals, service accounts, and cross-domain trusts before the certification is sent to business owners. Reviewers should not have to mentally reconstruct inheritance during approval; they should see the effective entitlement, the source path, and the business owner side by side.

A practical workflow usually includes four steps:

• Resolve group nesting to the final access set for each user, service account, and NHI.
• Map trust boundaries and domain relationships so reviewers can see where access originates.
• Annotate each entitlement with source system, owner, last use, and exception status.
• Route decisions to the accountable manager, with remediation tickets for removals, not just approvals.

Where AD is paired with cloud identity, the review should also reconcile hybrid join paths and directory sync artifacts, because a single account can inherit access from multiple control planes. The NHI Lifecycle Management Guide is useful here because the same principle applies to non-human accounts: every entitlement needs a known owner and a lifecycle state. On the standards side, NIST SP 800-53 Rev 5 Security and Privacy Controls supports periodic access review, least privilege, and accountable authorization records, while OWASP Non-Human Identity Top 10 highlights the same entitlement sprawl problem for machine identities.

The review package should also separate “technically present” from “operationally required.” A dormant permission may still exist because a legacy application needs it, but that exception must be documented with an expiry date and a named owner. These controls tend to break down when directory data is fragmented across multiple forests and stale trust metadata cannot be reconciled back to a single source of truth.

Common Variations and Edge Cases

Tighter review controls often increase analyst workload, requiring organisations to balance audit defensibility against operational effort. That tradeoff is most visible in environments with multiple forests, external trusts, resource accounts, and shadow IT groups created outside standard provisioning.

There is no universal standard for this yet, but current guidance suggests a risk-based approach. High-impact groups should be reviewed at the effective-access level, while lower-risk groups can be sampled if the organisation has strong automated detection of nesting changes. The same is true for foreign security principals: they should not be treated as a generic membership line item, because the real question is whether the trusted domain still deserves access.

One common edge case is service or automation accounts that appear as ordinary principals in group membership. These accounts often need separate governance because revocation can break integrations, but leaving them unreviewed is equally dangerous. Another is delegated administration, where local IT teams create nested groups to simplify operations. In those cases, the review should trace responsibility back to the team that can actually remove or reassign the access, not just the last approver in the workflow.

For most mature programs, the best practice is evolving toward continuous entitlement reconciliation rather than annual certification alone. In hybrid environments, that approach aligns with NHI governance lessons from Top 10 NHI Issues and the access-risk discipline described by NIST Cybersecurity Framework 2.0.

Related resources from NHI Mgmt Group

• How should security teams govern Active Directory service accounts?
• How should security teams govern Active Directory access across multiple databases?
• How should security teams run access reviews for non-human identities?
• How should security teams govern non-human identities that have persistent access?