Session access assumes the person who logged in is the person who acts until logout. Delegation for agents must preserve a machine-readable chain from user to agent to downstream service, because the actor executing the task may not be the original requester. That makes signed claims and on-behalf-of records essential.
How delegation for agents differs from session access for users
Session access is built around a stable human principal: the logged-in user is presumed to be the actor until the session ends. Delegation for agents is different because the task may be executed by software on behalf of someone else, so the security model must preserve who requested the action, who approved it, and what downstream authority was exercised.
Why the trust model changes when the actor is an agent
The key difference is not just “automation versus manual use”, but how authority is represented. A user session can often rely on a single authenticated principal and a bounded session state. Delegated agent activity needs explicit identity chaining, so the system can answer whether an action came from the human, the agent, or a downstream service acting under delegated authority.
That distinction matters because the agent may need narrower or different access than the user, and the agent’s actions may span multiple services. If the chain is not preserved, attribution breaks, approval evidence becomes weak, and revocation becomes harder when the task or context changes.
What must be preserved in a delegation chain
Agent delegation should carry machine-readable claims that survive across hops, not just a bearer session that says “someone logged in”. In practice, that means preserving the original requester, the agent identity, the target resource, and the scope or purpose of the action so downstream systems can make a decision based on the real actor and the real intent.
This is why on-behalf-of patterns, signed assertions, and token exchange matter. They let the receiving service distinguish direct user sessions from delegated execution, and they create a durable record that can be audited, constrained, or denied when the requested task exceeds policy.
- User session: one principal, one session, one continuity assumption until logout.
- Agent delegation: multiple principals in the chain, with explicit provenance from requester to executor.
- Downstream service access: authorization should depend on the delegated claim set, not just the fact that a valid credential exists.
Risk and Threat Considerations
The main risk is authority confusion. If delegated agent actions are treated like ordinary user sessions, the system can over-attribute privileges to the agent, under-record the original requester, or miss the point where approval should have been rechecked.
Failure mechanism: A reusable session token or loosely scoped credential is replayed across tasks or services without preserving the actor chain, so downstream systems cannot tell whether the action is still within the approved delegation boundary.
Impact: Overscoped access, weak auditability, and harder incident response follow, especially when an agent can invoke multiple services or act after the original user intent has expired.
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 addresses the attack and risk surface, while NIST SP 800-53 Rev 5 sets the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST SP 800-53 Rev 5 | IA-9 — Service Identification and Authentication | Delegated agent access depends on authenticating non-human services in the chain. |
| AC-6 — Least Privilege | Delegated access should be narrower than the user's full standing rights. | |
| Recommendation — Require service authentication that distinguishes delegated agent execution from user sessions. Limit delegated access to the minimum permissions needed for the task. | ||
| OWASP Agentic AI Top 10 | ASI03 — Identity & Privilege Abuse | Agent delegation can overextend authority when identity and privilege are not separated. |
| ASI09 — Human-Agent Trust Exploitation | Delegation relies on human trust that can be abused if approvals are too broad. | |
| Recommendation — Constrain agent privilege to the minimum approved scope for each action. Bind approvals to explicit task scope and recheck trust at each sensitive step. | ||
Practitioner Guidance
What to verify: Confirm that delegated actions carry a verifiable claim chain from user to agent to resource, and that the receiving service can enforce scope and audience from those claims rather than from the session alone.
Decision rule: If the action changes authority, crosses service boundaries, or can persist beyond the user interaction, treat it as delegation and require explicit on-behalf-of semantics, not ordinary session reuse.
Common mistake: Reusing human session assumptions for agent execution. That shortcut usually works only until audit, revocation, or policy enforcement becomes necessary, then the system has no reliable way to prove who did what.
Practitioner takeaway: Session access is about continuity of a user login; delegation is about preserving accountable authority across actors, so the security design must make the delegation chain first-class.
Related resources from NHI Mgmt Group
- What is the difference between managed identities and hardcoded secrets for AI agents?
- What is the difference between workload identity and API keys for AI agents?
- What is the difference between governing human access and governing AI agent access?
- What is the difference between logging actions and logging intent for AI agents?