Custom attributes are additional identity or user properties supplied by an identity provider and carried into application context. They help applications make more informed access decisions by adding details such as organization membership, department, or other claims that can be used in tokens or membership lookups.
Expanded Definition
Custom attributes are supplementary identity claims that an identity provider attaches to a subject and passes into application context for policy evaluation, authorization, or personalization. In NHI environments, they often represent department, environment, workload class, owner, cost centre, or trust zone, and they may be embedded in tokens, fetched through directory lookups, or mapped into policy engines.
Although the concept is straightforward, usage varies across vendors and integration patterns. Some platforms treat custom attributes as authoritative claims, while others treat them as mutable metadata that should be validated against a source of truth. That distinction matters because attributes used for access control should be stable, well-governed, and minimally exposed. In practice, they work best when paired with zero trust principles and explicit policy logic, as described in the NIST Cybersecurity Framework 2.0 and related identity governance models.
Within NHI Management Group guidance, custom attributes become security-relevant when they influence machine-to-machine authorisation, especially where an agent, service account, or API client receives broader permissions because a claim is present but not verified. The most common misapplication is treating custom attributes as trusted access facts when they are actually stale, user-editable, or copied from an upstream directory without validation.
Examples and Use Cases
Implementing custom attributes rigorously often introduces schema governance overhead, requiring organisations to weigh richer policy decisions against the operational cost of maintaining attribute quality and lineage.
- A service account receives an attribute such as Ultimate Guide to NHIs source-aligned workload ownership, and a policy engine uses it to limit API access to a single environment.
- An AI agent is tagged with an application domain attribute so it can only call tools relevant to finance, rather than all available internal connectors.
- A CI/CD pipeline token carries a deployment-stage attribute, allowing production approval workflows to deny non-production build credentials from promoting release actions.
- An organisation maps department or cost-centre attributes into NIST Cybersecurity Framework 2.0-aligned access rules so that access decisions reflect current business ownership.
- A directory lookup enriches a machine identity with ownership and environment metadata before the token is evaluated by an API gateway.
These use cases are useful when the attribute is deterministic and governed. They are risky when teams allow local application teams to invent inconsistent attribute names, duplicate meanings, or use the same field for both business context and security control.
Why It Matters in NHI Security
Custom attributes can improve least privilege, but they can also become an invisible trust bypass if they are inaccurate, over-broad, or copied from weak upstream sources. In NHI programs, attributes often determine whether a workload can reach production data, assume a role, or satisfy a policy condition. If the attribute model is poorly governed, the result is privilege creep, misrouted access, and brittle policies that fail open when a claim is missing.
This matters because NHIs already operate at scale and are frequently over-permissioned. NHI Mgmt Group reports that Ultimate Guide to NHIs data shows 97% of NHIs carry excessive privileges, which makes attribute-driven access decisions especially sensitive to mistakes in claim design or validation. Properly governed attributes help organisations express context without hardcoding exceptions into applications, but only if ownership, lifecycle, and source-of-truth rules are explicit.
Organisations typically encounter the real impact only after a mis-scoped token, unintended role grant, or service account compromise exposes a path that the attribute model was supposed to restrict, at which point custom attributes become 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 | Custom attributes shape authorization context and can create privilege expansion if unchecked. |
| NIST CSF 2.0 | PR.AC-4 | Attribute-based access depends on maintaining least-privilege permissions and contextual access control. |
| NIST Zero Trust (SP 800-207) | PL-4 | Zero trust policy engines rely on trusted identity context, including attributes, for decisions. |
| NIST SP 800-63 | Identity assertions must be trustworthy when attributes are used as security-relevant claims. | |
| OWASP Agentic AI Top 10 | A2 | Agentic systems use context claims to scope tool access and reduce unsafe action radius. |
Treat custom attributes as policy inputs that must be validated before each authorization decision.
Related resources from NHI Mgmt Group
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Reviewed and updated by the NHIMG editorial team on August 28, 2026.
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