Who should be allowed to use Tier 0 or Tier 1 access in practice?

Why This Matters for Security Teams

Tier 0 and Tier 1 access are not just higher privilege levels. They are the paths that can reshape trust, alter enforcement, and expose the identity fabric itself. When access is granted broadly or managed informally, the blast radius is usually much larger than teams expect. NHI Mgmt Group notes that 97% of NHIs carry excessive privileges in the Ultimate Guide to NHIs, which is exactly why tiered access must be tied to operational necessity, not convenience.

This question matters because Tier 0 and Tier 1 are often treated as permanent roles instead of exceptional access paths. That model breaks down when service accounts, admin bots, break-glass workflows, and vendor support channels all converge on the same privileged systems. The right control question is not who is “trusted” in a general sense, but who has a documented need, a bounded scope, and a reviewable path for each use case. Current guidance from the OWASP Non-Human Identity Top 10 and NIST SP 800-53 Rev 5 Security and Privacy Controls strongly supports least privilege and accountable elevation, but implementation still varies widely across enterprises. In practice, many security teams encounter Tier 0 misuse only after an incident has already turned a routine admin path into an attack path.

How It Works in Practice

Allowed users should be limited to identities that can prove why they need Tier 0 or Tier 1 access, when they need it, and how that access will be monitored. For human operators, that usually means dedicated administrators with separate admin accounts, tightly scoped response teams, and exceptional vendor access that is time-bound and fully supervised. For non-human identities, the same logic applies but the mechanism changes: the workload must authenticate as a specific NHI, use the smallest viable permission set, and receive access only for a defined task window.

Operationally, that usually means combining strong identity proofing, privileged access management, and just-in-time elevation. Access should be short-lived, task-specific, and revoked automatically when the job ends. Reviewability matters as much as issuance, so every Tier 0 or Tier 1 action should be tied to logs that show who or what requested it, what policy allowed it, and what systems were touched. That is especially important for service accounts and automation paths discussed in the Ultimate Guide to NHIs — Key Challenges and Risks, where standing privileges and hidden credentials are common failure points.

• Use separate admin identities, not shared daily-use accounts.
• Issue Tier 0 or Tier 1 access only through documented approval and expiry.
• Require session recording or equivalent audit evidence for privileged use.
• Apply the same scrutiny to human, service, and vendor identities.
• Revoke access automatically when the operational need ends.

These controls tend to break down in legacy environments where shared credentials, hard-coded secrets, or unsegmented administrative networks make attribution and revocation impractical.

Common Variations and Edge Cases

Tighter privileged access often increases operational overhead, requiring organisations to balance rapid incident response against strong review and separation of duties. That tradeoff is real in emergency remediation, regulated maintenance windows, and vendor-supported recovery scenarios. Best practice is evolving, but current guidance suggests that exceptions should be narrow, logged, and pre-approved wherever possible rather than improvised during an outage.

One common edge case is break-glass access. It should exist, but only as an exception path with compensating controls such as MFA, short TTLs, immediate alerting, and post-use review. Another is automation that needs temporary elevation to restart services, rotate keys, or repair failed deployments. That access should be granted to a dedicated workload identity, not to a broad shared admin role. NHIMG research on the 52 NHI Breaches Analysis shows how often weak identity hygiene becomes a privilege escalation path, especially where review trails are missing.

Rare vendor exceptions can be justified, but only if the access is named, scoped, observed, and time-boxed. Where organisations cannot independently review the path, the access should be treated as untrusted. That principle is often the difference between controlled support and invisible lateral movement.

Related resources from NHI Mgmt Group

• How should security teams run access reviews for non-human identities?
• How should security teams govern non-human identities that have persistent access?
• When do NHI access reviews create more value than a one-time cleanup?
• What is the difference between reviewing human access and reviewing NHIs?