An identity explicitly exempted from a policy restriction. It is useful for break-glass or continuity scenarios, but it also creates a privileged bypass path that must be tightly owned, monitored, and periodically removed if it is no longer required.
Expanded Definition
An excluded principal is a service account, workload identity, or other NHI that is explicitly carved out from a policy control so it can continue operating when a restriction would otherwise block it. In practice, exclusions are used for continuity, break-glass access, migration windows, and tightly scoped operational exceptions. The security issue is not the exception itself, but the fact that an exclusion can become a durable privileged bypass if ownership, expiry, and monitoring are weak.
Definitions vary across vendors, but in NHI governance the important distinction is between an intentional exemption and an unmanaged policy gap. A proper excluded principal should have an accountable owner, a documented reason, a time bound or review trigger, and compensating controls such as alerting or secondary approval. This aligns with the least-privilege intent reflected in the NIST Cybersecurity Framework 2.0 and the broader NHI visibility guidance in the Ultimate Guide to NHIs. The most common misapplication is treating a temporary exception as permanent, which occurs when teams leave a bypass in place after the original incident, rollout, or maintenance window has ended.
Examples and Use Cases
Implementing excluded principals rigorously often introduces operational friction, requiring organisations to weigh continuity during incidents against the risk of creating an enduring privileged path.
- A break-glass service account is excluded from a rotation policy so responders can restore access during an outage, but the exception is logged, time limited, and reviewed after each use.
- A legacy API client is excluded from a new authentication enforcement rule while a migration is underway, using compensating monitoring until the workload is updated.
- A deployment pipeline principal is excluded from a network restriction because it must reach a bootstrap endpoint, but the exemption is paired with tight source IP and approval controls.
- A third-party integration is temporarily excluded from a conditional access rule during remediation, then removed once the vendor supports the required control set.
- A recovery identity is excluded from a policy that blocks dormant accounts, because continuity depends on its availability, but ownership and test use are formally scheduled.
In all of these cases, the exemption should be narrower than the underlying control. That practice is consistent with identity-centric guidance from the Ultimate Guide to NHIs and with zero trust expectations described in the NIST Cybersecurity Framework 2.0.
Why It Matters in NHI Security
Excluded principals matter because they are one of the easiest ways for a control to be bypassed without appearing broken. A policy may look effective on paper while a hidden set of exemptions preserves the exact access path an attacker would want. This is especially dangerous in NHI environments, where privileged service accounts, API keys, and automation identities already create broad blast radius if they are overexposed or poorly governed.
NHIMG research shows that 97% of NHIs carry excessive privileges, and 5.7% of organisations have full visibility into their service accounts. That combination means an exclusion can be both hard to see and highly impactful. The governance problem is not limited to access control design. It also affects incident response, secret rotation, offboarding, and audit readiness, which is why the Ultimate Guide to NHIs treats visibility and lifecycle enforcement as core controls rather than optional hygiene. Exclusions should therefore be reviewed like privileged access, not like documentation footnotes.
Organisations typically encounter the risk after an outage, audit finding, or compromise reveals that an exception remained active long after its original purpose expired, at which point excluded principal management becomes operationally unavoidable to address.
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 and OWASP Agentic AI Top 10 address the attack and risk surface, while NIST CSF 2.0, NIST Zero Trust (SP 800-207) and NIST SP 800-63 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-04 | Excluded principals create policy bypass paths that must be owned and time bound. |
| NIST CSF 2.0 | PR.AC-4 | Least privilege requires reviewing and limiting explicit policy exemptions. |
| NIST Zero Trust (SP 800-207) | PLV-3 | Zero trust discourages standing trust, including broad exceptions from policy enforcement. |
| NIST SP 800-63 | Identity assurance is weakened when identities are exempted from normal controls. | |
| OWASP Agentic AI Top 10 | A-04 | Agentic systems can abuse exempted identities to reach restricted tools or data. |
Inventory every exception, assign an owner, and remove excluded principals when the business need ends.
