Because the agent can often retrieve or use those credentials as part of normal tool execution. If a compromise occurs, secrets in files, environment variables, or gateway configs become immediate targets, and the attacker can pivot from assistant behaviour to authenticated access. The risk is amplified when secrets persist beyond one session.
Why runtime-stored credentials change the agentic risk profile
Agentic systems are different from passive software because they do not just hold credentials, they actively use them while acting on a user’s behalf. When secrets sit in the same runtime that drives tool calls, a compromise of the agent, its plugin, or its surrounding process can turn directly into authenticated access. That collapses the separation between “assistant behaviour” and “credential holder”.
Runtime placement also widens the blast radius. If the secret lives in memory, files, environment variables, or gateway configuration, the agent may be able to retrieve it exactly when it needs it, which is convenient for automation but dangerous under abuse. The problem is not only theft, it is that the attacker inherits the same execution path the agent uses for normal work.
Persistence makes this worse. A credential that survives beyond one task or session can be reused after the original action is complete, so a single compromise can extend into later tool execution, data access, or downstream API use. Secret sprawl becomes especially harmful when the secret is both reachable at runtime and broadly reusable.
How attackers turn normal tool execution into authenticated abuse
The key failure mode is that the agent’s runtime becomes a credential handling surface as well as an execution surface. If an attacker can influence prompts, poison a tool response, exploit a local dependency, or obtain code execution in the surrounding environment, they often do not need a separate password theft step. The runtime already contains the material needed to call APIs, gateways, or backends as a trusted principal.
That creates a fast pivot path: compromise the agent process, extract the secret, then use the valid credential outside the agent. In practice, this is why over-scoped tokens, long-lived keys, and static secret injection are so risky in autonomous systems. Least-privilege authorisation for AI agents is not just about limiting what the agent may ask for, it is about limiting what a stolen runtime secret can do if the agent is subverted.
Session boundaries matter too. If credentials are copied into every run without tight expiry, revocation, or audience restriction, the attacker can keep using them after the original agent action is over. That is especially dangerous when the same secret unlocks multiple tools, tenants, or environments.
What good practice looks like for agent credentials
Good design keeps runtime credentials short-lived, scoped to the narrowest useful action, and hard to exfiltrate from the environment where the agent runs. The goal is not to stop the agent from authenticating, it is to ensure the credential’s value disappears quickly if the runtime is compromised. Where possible, use delegated tokens, ephemeral credentials, or brokered access rather than embedding durable secrets in process state.
It also helps to separate “the agent can act” from “the agent can see the secret”. If the platform can pass an access decision or exchange a token at the moment of use, the system is much less exposed than if the secret is stored in a file, shell variable, or shared config. Secrets management guidance is most valuable here when it is paired with runtime containment, not treated as a vault-only problem.
When the agent needs external services, prefer a pattern where the service enforces its own authorisation and the agent receives only the minimum token or delegated capability needed for the current action. That reduces the chance that a compromise of one runtime becomes a platform-wide compromise.
Risk and Threat Considerations
Runtime-stored credentials create a direct compromise path from agent execution to authenticated abuse. If the agent environment is subverted, the attacker often gets immediate access to tokens, API keys, or gateway settings that were meant to support automation, not survive hostile control.
Failure mechanism: The credential is reachable from the same runtime that executes prompts, tools, and plugins, so any compromise of the agent process, container, or orchestration layer can expose a valid secret for reuse outside the intended session.
Impact: Attackers can pivot from manipulating agent behaviour to using real authenticated access, which can lead to data exposure, API abuse, privilege escalation, and persistent access until the secret is rotated or revoked.
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 SP 800-53 Rev 5, NIST Zero Trust (SP 800-207) and CSA Cloud Controls Matrix set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-02 — Secret Leakage | Runtime-stored credentials are exposed to theft from the agent environment. |
| NHI-07 — Long-Lived Secrets | Persistent runtime credentials extend attack windows beyond one session. | |
| NHI-05 — Overprivileged NHI | A stolen runtime secret can grant more access than the task requires. | |
| Recommendation — Reduce exposure by removing durable secrets from agent runtimes and rotating any leaked credentials. Replace long-lived keys with short-lived credentials and enforce rapid revocation. Scope agent credentials to the minimum permissions needed for each action. | ||
| OWASP Agentic AI Top 10 | ASI03 — Identity & Privilege Abuse | Compromised agent runtimes can be abused to obtain and use privileged access. |
| ASI02 — Tool Misuse | Tool execution is the moment when a runtime credential can be abused. | |
| Recommendation — Constrain agent authority so stolen runtime credentials cannot be reused broadly. Bind tool access to per-action decisions and limit credential reach at each call. | ||
| NIST SP 800-53 Rev 5 | IA-5 — Authenticator Management | The question centers on storing, using, and revoking runtime credentials safely. |
| AC-6 — Least Privilege | Agent credentials should not confer more access than the task requires. | |
| IA-9 — Service Identification and Authentication | Agent runtimes commonly authenticate services, APIs, and workloads to each other. | |
| Recommendation — Manage credential lifecycle tightly and revoke secrets as soon as they are no longer needed. Limit each agent credential to the smallest set of permitted actions and resources. Use service authentication patterns that avoid exposing reusable long-lived secrets in the runtime. | ||
| NIST Zero Trust (SP 800-207) | Zero Trust Architecture | The answer depends on reducing implicit trust in the agent runtime after compromise. |
| Recommendation — Continuously verify each request and avoid assuming the runtime remains trustworthy. | ||
| CSA Cloud Controls Matrix | IAM — Identity & Access Management | Cloud and platform identity controls govern how runtime credentials are issued and used. |
| Recommendation — Apply cloud identity controls that constrain issuance, scope, and lifecycle of runtime credentials. | ||
Practitioner Guidance
What to prioritise: Treat any secret that the agent can read during normal execution as a high-value blast-radius item. If it can authenticate to production systems, it deserves the same urgency as a compromised admin credential, not the same handling as a harmless config value.
What to verify: Check whether the agent actually needs direct access to the underlying secret, or whether a broker, exchange, or ephemeral token can satisfy the same workflow. Verify expiry, audience, scope, and revocation behaviour before trusting the design.
Common mistake: Teams often centralise secrets and assume that is sufficient. Central storage helps inventory, but if the runtime can fetch and reuse a durable credential during every task, compromise still turns into immediate authenticated access.
Practitioner takeaway: The security question is not whether the agent uses credentials, it is whether those credentials remain useful to an attacker after the agent runtime is touched.