Look for agent actions that succeed because a credential is broadly valid, not because the action was explicitly approved. Warning signs include alternate-token discovery, destructive tool calls outside the original task, and audit logs that show only credential use rather than a human-approved decision path.
What failure looks like at runtime
runtime authorisation is failing when an agent can complete a meaningful action without a fresh, explicit permission decision for that action. The strongest signal is not “the agent had access”, but “the agent had enough standing access to act beyond intent.” That can show up as task drift, unexplained escalation, or a tool invocation that should have been gated but was not.
Security teams should treat successful execution as suspect when the approval path is missing or invisible. If the logs show only valid credential use, but not the decision that bound that use to the specific task, the control may be authenticating the agent while failing to authorise the action.
One practical way to think about the problem is to separate permission to exist from permission to act. An agent can be correctly authenticated, yet still bypass runtime authorisation if its token, role, or delegation scope is too broad for the operation it performed.
What to look for in logs and tool traces
Detect failure by comparing the intended task, the granted scope, and the actual tool calls. AI Agent Authorisation Guide is useful here because it frames per-action decisions, just-in-time access, and human approval as distinct from broad agent permissions.
Look for alternate-token discovery, unexpected credential reuse, and calls to destructive or sensitive tools outside the original workflow. Those patterns suggest the agent found a path around the policy boundary rather than operating within a bounded approval chain.
Audit trails should also show whether the system recorded a policy decision, not just an API call. If the only evidence is “credential accepted” or “token valid”, but there is no record of policy evaluation, scope narrowing, or human approval, then the runtime control is too shallow to prove authorisation happened.
How teams should interpret the warning signs
Not every out-of-scope call means compromise. Some failures are policy design issues, such as overly broad delegation, inherited roles, or a tool wrapper that never enforced action-specific checks. Authorisation Models Guide helps distinguish coarse role grants from finer policy decisions, which matters when the question is whether runtime authorisation is actually happening.
Runtime failure becomes material when the agent can chain from one permitted action into a second, more sensitive one without a new decision point. That is the boundary security teams need to test: whether the control stops at identity validation, or really evaluates each action against context, purpose, and current risk.
For agent estates with many credentials and workflows, lifecycle hygiene also affects detection quality. NHI Lifecycle Management Guide is relevant because stale, over-retained, or poorly inventoried credentials make it much harder to tell whether a runtime action was legitimate or simply made possible by dormant access.
Risk and Threat Considerations
When runtime authorisation fails, the immediate risk is privilege expansion: an agent can move from routine task execution to destructive or data-bearing actions using a credential that was never meant to cover that scope. Attackers also benefit from this failure mode because it lets them abuse normal-looking credential use while bypassing the decision layer that should have constrained the action.
Failure mechanism: The policy layer approves the identity or token, but not the specific action, so the agent inherits broad standing rights and can execute unsafe tool calls, access adjacent systems, or continue operating after task boundaries should have ended.
Impact: Teams lose action-level accountability, blast radius increases, and incident responders may see only “valid use” in the logs even though the agent acted outside intent. That weakens containment, makes abuse harder to prove, and can turn a single delegated session into a broader compromise path.
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 and OWASP Non-Human Identity Top 10 address 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 |
|---|---|---|
| OWASP Agentic AI Top 10 | ASI03 — Identity & Privilege Abuse | Runtime authorisation failure shows agents acting beyond approved identity scope. |
| ASI02 — Tool Misuse | Destructive or out-of-task tool calls are the core runtime failure signal. | |
| Recommendation — Enforce per-action approvals and least privilege for high-impact agent actions. Constrain tools to task-scoped permissions and block unsafe call paths. | ||
| OWASP Non-Human Identity Top 10 | NHI-05 — Overprivileged NHI | Broad valid credentials enabling actions without explicit approval indicate excess privilege. |
| Recommendation — Reduce standing access and scope credentials to the minimum required action. | ||
| NIST SP 800-53 Rev 5 | AC-3 — Access Enforcement | Access must be enforced at the action level to prevent unintended agent operations. |
| AU-2 — Event Logging | Logs need to show decisions and action context, not just credential use. | |
| Recommendation — Enforce authorization decisions before sensitive tools execute. Log policy decisions and sensitive tool invocations for later review. | ||
Practitioner Guidance
What to verify: Confirm that every high-impact tool call has a policy decision tied to the current task, not just a valid bearer token. If your evidence chain cannot show “who approved this action, under what context, and for how long,” runtime authorisation is not strong enough to trust.
What to measure: Track the share of sensitive actions that are covered by per-action policy checks, plus the number of successful calls made with credentials that were broader than the task required. A rising gap between intended scope and executed scope is an early warning that the control is degrading.
Common mistake: Treating token validity as proof of authorisation. For agents, valid authentication is only the starting condition; the control succeeds only when the system can enforce and record action-specific approval before the tool executes.
Practitioner takeaway: The most useful detection question is not “did the agent authenticate?”, but “can we prove the exact action was approved at the moment it was taken?” If the answer is no, the authorisation boundary is already too weak for safe agent operation.
Related resources from NHI Mgmt Group
- How should security teams manage permissions for AI agents?
- How should security teams govern AI agents that use OAuth access?
- How should security teams limit the risk from AI agents that have access to production systems?
- How should security teams govern AI agents that can access enterprise systems?