Who is accountable when zero trust controls exist but access remains over-provisioned?

Why This Matters for Security Teams

zero trust can validate every request and still leave an environment exposed if identities retain broad standing permissions. That is why accountability cannot sit with a single team. IAM owns entitlement design, security architecture owns the control model, and application owners own the business logic that determines what access is actually needed. NIST’s Zero Trust Architecture makes verification central, but it does not eliminate the need to continuously reduce access scope. The governance gap is especially visible in NHI-heavy estates where service accounts, tokens, and API keys outlive the workload they support, a pattern discussed in NHIMG’s Ultimate Guide to NHIs — Key Challenges and Risks.

When over-provisioning persists, the control failure is not usually in the policy engine alone. It is in the ownership model that never reconciles business need with effective permissions. Security teams often discover this only after access reviews surface dormant entitlements, rather than through intentional privilege minimisation.

How It Works in Practice

Operational accountability should be split by decision layer. IAM should define how identities are issued, authenticated, and reviewed. Security architecture should define the zero trust policy, including conditional access, segmentation, and verification requirements. Application owners should define the minimum functional access each workload or user path needs. If any one of those layers is weak, the environment can remain over-provisioned even when authentication is strong.

Practitioners should treat access scope as a separate control from access verification. That means reviewing role definitions, service account entitlements, and group memberships against real workload behaviour. For NHIs, the baseline should come from workload identity and lifecycle evidence, not from manual assumptions. NHIMG’s Guide to SPIFFE and SPIRE is relevant here because strong workload identity helps show what the workload is, while zero trust policy determines what it may do at runtime.

• Use policy-as-code to evaluate access at request time, but still review entitlement scope on a schedule.
• Assign one accountable owner for each privileged role, service account, or application permission set.
• Measure standing access, unused permissions, and exception age as separate metrics.
• Require application owners to justify each non-default permission, not just approve the final access request.

Current guidance suggests pairing zero trust enforcement with entitlement governance because one without the other leaves excessive permissions intact. The OWASP Non-Human Identity Top 10 reinforces that NHI misuse is often enabled by static credentials and excessive privilege, not only by weak authentication. These controls tend to break down in fast-moving cloud and CI/CD environments because permissions change faster than ownership reviews can keep up.

Common Variations and Edge Cases

Tighter access governance often increases operational overhead, requiring organisations to balance faster delivery against stronger privilege discipline. In mature environments, that tradeoff is acceptable when the business impact of misuse is high; in lower-risk systems, the review cadence may be lighter, but it should still exist.

There is no universal standard for this yet, but current guidance is converging on three patterns. First, zero trust policy should be enforced at runtime, not only at onboarding. Second, over-provisioned access should be treated as an entitlement defect, even if the authentication path is strong. Third, accountability must follow the control gap: IAM for entitlement design, security architecture for policy enforcement, and application owners for permission justification.

NHIMG’s Top 10 NHI Issues and Ultimate Guide to NHIs — Standards are useful when teams need to separate authentication maturity from entitlement hygiene. The edge case most organisations miss is delegated access: if one platform inherits another team’s permissions, both owners can assume the other is handling review. That ambiguity is where over-provisioning survives longest.

Related resources from NHI Mgmt Group

• Who is accountable when zero-trust controls fail to reduce access over time?
• Who is accountable when server access remains active after offboarding?
• Who is accountable when access remains after offboarding?
• Who is accountable when zero trust coverage is only partial?