Security teams should govern machine-account delegation the same way they govern privileged user delegation, by treating Tier 0 computers as sensitive identities that must not be representable across tiers unless there is a documented business need. The control must be verified at the directory attribute level, because console visibility is incomplete and can hide the real exposure.
Why This Matters for Security Teams
Kerberos delegation for machine accounts is a high-impact identity control because it can silently extend a computer’s authority beyond its intended tier. When a Tier 0 system is trusted for delegation, attackers who compromise that machine can often pivot into privileged services without needing to crack a human account. This is an identity problem first, and a Windows configuration problem second. NHI Management Group’s guidance on lifecycle and governance in the Ultimate Guide to NHIs — Lifecycle Processes for Managing NHIs frames the operational reality: machine identities need explicit ownership, scope, and review, not inherited trust.
The key mistake is relying on console summaries instead of directory attributes, because delegation exposure is often only visible where the account object is actually stored. That is why this control belongs in the same governance family as NIST Cybersecurity Framework 2.0 access governance and asset protection. In practice, many security teams discover dangerous delegation paths only after a lateral movement incident has already mapped them for free.
How It Works in Practice
Governance starts by classifying machine accounts by tier and function, then verifying whether delegation is enabled, constrained, or unrestricted at the attribute level. For Kerberos, the relevant question is not whether a host appears “managed,” but whether it can present or impersonate credentials to downstream services. That means reviewing directory objects for delegation settings, service principal exposure, and any account that can authenticate across trust boundaries.
Current best practice is to treat Tier 0 computers as sensitive identities and prohibit representable delegation unless there is a documented business need, explicit approval, and compensating monitoring. Security teams should tie this to their broader NHI control set:
- Inventory all machine accounts, then tag Tier 0 systems separately from lower-trust assets.
- Check delegation directly in Active Directory attributes, not only in admin consoles.
- Prefer constrained delegation over unconstrained delegation where delegation is unavoidable.
- Review who can modify delegation settings, because delegated administration can become indirect privilege escalation.
- Pair the review with NHI lifecycle controls from the Top 10 NHI Issues so exceptions are tracked, time-bound, and revisited.
Control design should also align with authentication assurance and access governance patterns in the Ultimate Guide to NHIs — Regulatory and Audit Perspectives, because auditors will look for evidence that the effective exposure matches policy. These controls tend to break down in large Active Directory estates where delegated admin teams can change attributes faster than security review cycles can detect them.
Common Variations and Edge Cases
Tighter delegation control often increases operational overhead, requiring organisations to balance service reliability against privilege reduction. That tradeoff becomes sharper in environments with legacy applications, clustered services, or vendor-managed systems that still depend on older Kerberos patterns. Best practice is evolving here, and there is no universal standard for every application dependency.
One common edge case is when a machine account must delegate for application-to-application authentication, but the business owner cannot clearly explain the downstream service chain. In those cases, temporary exceptions are safer than permanent broad delegation, especially when the account spans domains or supports administrative tooling. Another edge case is false assurance from “hidden” GUI states: if the object-level attributes are not reviewed, the security team may miss representable delegation even though the host looks hardened.
For audit and remediation, the useful question is whether the machine account can be prevented from crossing tiers by default. If not, the exception should be explicit, time-limited, and tied to monitoring that can detect abuse quickly. This is the same governance mindset described across NHI lifecycle controls and the NIST Cybersecurity Framework 2.0, where exposure management must be continuous rather than periodic.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP Non-Human Identity Top 10 address the attack and risk surface, while NIST CSF 2.0 and NIST Zero Trust (SP 800-207) set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-01 | Covers excessive trust and delegation in non-human identities. |
| NIST CSF 2.0 | PR.AC-4 | Addresses least-privilege access and identity permission governance. |
| NIST Zero Trust (SP 800-207) | PR.AC-5 | Supports restricting lateral movement through conditional trust decisions. |
Inventory machine-account delegation and remove any exposure that is not explicitly required.
