Why do service accounts and other NHIs expose internal control weaknesses?

Why This Matters for Security Teams

service account and other NHIs expose internal control weaknesses because they often sit outside the human-centric processes that were built to govern access, approvals, and accountability. Once a credential is embedded in automation, a pipeline, or an integration layer, it can outlive the original business need and become difficult to challenge during review. That makes weak ownership, missing documentation, and stale revocation paths more than housekeeping issues. They become control failures. NHI Management Group has documented how these failures show up in real incidents, including patterns covered in the 52 NHI Breaches Analysis.

The risk is not just that access exists. It is that access can be reused across systems, copied into multiple places, or left active after staff, apps, or vendors change. In the 2025 State of NHIs and Secrets in Cybersecurity, Entro Security reported that 60% of NHIs are overused by more than one application, and 91% of former employee tokens remain active after offboarding. That combination weakens least privilege, blurs accountability, and makes audits rely on inference instead of evidence. In practice, many security teams encounter the weakness only after an integration fails, a token is exposed, or a breach investigation reveals that no one can prove why the access still existed.

How It Works in Practice

The control weakness comes from the mismatch between how NHIs are used and how most organisations govern access. Humans are reviewed through joiner-mover-leaver processes, while service accounts, API keys, and automation identities are often created for a project and then inherited by every team that touches the workflow. Over time, the identity stops representing a single purpose and becomes an ambient privilege container.

That is why current guidance increasingly treats NHI governance as an identity lifecycle problem, not just a secrets storage problem. The practical steps usually include:

• Assigning a named owner for each NHI and requiring a business purpose.
• Binding every privileged service account to a documented system, environment, and expiry date.
• Using Ultimate Guide to NHIs material to map where identities are created, stored, and reused.
• Rotating secrets on a defined cadence and revoking unused credentials automatically.
• Reviewing effective access, not just assigned access, so hidden inheritance is visible.

For teams trying to harden the technical layer, the strongest external reference point is the principle set in the CISA Zero Trust Maturity Model, which reinforces continuous verification and least privilege. In mature environments, service accounts are treated as workload identities with narrow scopes, while secrets are delivered just in time instead of being permanently embedded in code or tickets. Where this breaks down is in legacy automation estates with shared credentials, unclear ownership, and no reliable inventory of where tokens are consumed.

Common Variations and Edge Cases

Tighter control over NHIs often increases operational overhead, so organisations have to balance governance strength against automation speed. That tradeoff is especially visible in environments where one service account supports many jobs, or where teams use the same token across staging, production, and emergency workflows. Best practice is evolving, but there is no universal standard for every case yet.

Some edge cases are especially problematic. Privileged break-glass accounts may need broader access than normal service accounts, but they still need monitoring, expiry, and explicit justification. Shared platform accounts may be unavoidable in older systems, yet they should be the exception, not the default. In cloud and CI/CD pipelines, the most common failure is not malicious misuse but silent sprawl: credentials copied into multiple repos, duplicated in ticketing systems, or never removed from inactive jobs. NHIMG research such as the Top 10 NHI Issues and the 2025 State of NHIs and Secrets in Cybersecurity shows that duplication, overuse, and stale tokens are recurring weaknesses, not isolated mistakes.

Security leaders should therefore focus on proof of ownership, proof of purpose, and proof of revocation. When those three things are missing, the organisation may still have controls on paper, but it cannot demonstrate that the controls are actually working.

Related resources from NHI Mgmt Group

• What problem does ownership attribution solve for service accounts and API keys?
• When do service accounts become a higher risk than ordinary user accounts?
• How should security teams govern Active Directory service accounts?
• Why do service accounts and other NHIs complicate GRC implementation?