An agent user is the child identity associated with an agent identity, created after the blueprint is authenticated and authorised. It is not a person, but it can still hold access and generate activity, so offboarding and attestations must cover it explicitly.
Expanded Definition
An agent user is the subordinate, machine-generated identity bound to an agent identity after the blueprint has been authenticated and authorised. It is distinct from the agent itself: the blueprint defines intent and permitted actions, while the agent user is the operational identity that actually carries credentials, sessions, and audit-bearing activity.
In NHI and agentic AI governance, the term matters because the agent user becomes the enforcement point for access, policy, and lifecycle control. That means it must be enrolled, monitored, rotated, and revoked with the same discipline applied to service accounts, API keys, and other NHIs. Definitions vary across vendors, and no single standard governs this yet, so organisations should document whether the agent user is a child principal, an impersonation identity, or a session-scoped execution identity. Guidance in the OWASP Top 10 for Agentic Applications 2026 and NIST AI Risk Management Framework reinforces the need to bound autonomous actions with explicit identity and oversight. The most common misapplication is treating the agent user as disposable infrastructure, which occurs when teams fail to assign it independent access, audit, and offboarding controls.
Examples and Use Cases
Implementing agent users rigorously often introduces lifecycle overhead, requiring organisations to weigh faster autonomous execution against stronger identity governance and revocation discipline.
- A coding agent receives a short-lived agent user that can open repositories, submit pull requests, and call CI tools, but cannot approve production merges without a separate control gate.
- An operations agent is issued an agent user tied to a blueprint approved by policy, then forced through rotation and attestation whenever the model, prompt set, or toolchain changes.
- A customer support agent uses a scoped agent user to retrieve records and draft replies, while human review remains mandatory for account changes and refunds.
- A supply-chain agent is granted an agent user that can query vendors and update tickets, with activity logged for later investigation using patterns discussed in the Ultimate Guide to NHIs — 2025 Outlook and Predictions.
- A threat-detection workflow uses the agent user as the auditable identity layer, aligning implementation thinking with the NIST AI Risk Management Framework and the OWASP NHI Top 10.
In practice, the most useful test is whether the agent user can be revoked without breaking the underlying blueprint, because that separation makes incident response and policy changes far easier.
Why It Matters in NHI Security
Agent users are where abstract agent policy becomes enforceable security posture. If they are not uniquely identified, they blend into generic machine traffic and create blind spots in access review, detection, and offboarding. That is especially dangerous in environments where NHIs already outnumber human identities by 25x to 50x, according to NHI Mgmt Group’s Ultimate Guide to NHIs. When identity sprawl is this large, losing track of one child identity can expose the entire agent estate.
The governance risk is not theoretical. An agent user with stale privileges can continue acting after the blueprint is retired, the vendor changes, or the model is repurposed. That creates a path for overreach, data leakage, and unauthorised tool use, especially when the identity is not covered by explicit offboarding and attestation. Security teams should treat agent users as first-class NHIs and align controls with agentic threat models in the MITRE ATLAS adversarial AI threat matrix and CSA MAESTRO agentic AI threat modeling framework. Organisations typically encounter the consequences only after an agent has already acted outside its intended scope, at which point the agent user 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 Agentic AI Top 10 address the attack and risk surface, while NIST AI RMF and NIST CSF 2.0 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Agentic AI Top 10 | NHI-02 | Agent users are the identity layer OWASP flags for agentic access and secret misuse. |
| NIST AI RMF | NIST AI RMF frames accountable, monitored AI action as a governance requirement. | |
| NIST CSF 2.0 | PR.AA-01 | Identity management and authentication controls apply directly to machine identities. |
Inventory agent users, authenticate them strongly, and revoke them when the blueprint changes.
