TL;DR: Idle API keys, tokens and service accounts can remain valid for months or years after they stop being used, creating silent access paths that evade traditional monitoring and rotation controls, according to Entro Security's analysis of NHI sprawl. Lifecycle governance matters because forgotten credentials turn into persistent attack surface.
At a glance
What this is: Entro Security examines how idle NHIs and secrets create long-lived access risk when credentials remain valid after use stops.
Why it matters: This matters because IAM and PAM teams need to govern NHI lifecycle, not just detect active abuse, or stale credentials keep expanding the attack surface.
By the numbers:
- NHIs outnumber human identities by 25x to 50x in modern enterprises, according to the Ultimate Guide to NHIs.
Context
Idle secrets are credentials that remain valid after the workload, service, or project that created them is no longer actively using them. In NHI programmes, that creates a governance gap because ownership, expiry, and revocation controls often lag behind deployment speed.
This article focuses on service accounts, API keys, tokens, and certificates that are left unrotated or unrevokeed across distributed environments. The core problem is not visibility alone. It is the persistence of access rights after the business need has ended, which lets old credentials behave like current ones.
Entro Security argues that many organisations still treat non-human access as static infrastructure rather than managed identity lifecycle. That framing is increasingly wrong because unused credentials can remain live for months or years and become easy entry points for attackers.
Key questions
Q: What breaks when idle NHI secrets are not rotated or revoked?
A: When idle secrets are not rotated or revoked, the organisation loses the distinction between active and abandoned access. A still-valid API key or service account can remain usable long after the workload changed, which lets attackers authenticate quietly and persist without triggering the human login signals many teams monitor.
Q: Why do service accounts and API tokens create more risk when they are long-lived?
A: Long-lived service accounts and API tokens create more risk because exposure and exploitation can happen long before defenders notice. If the credential remains valid after discovery, the attacker can reuse it repeatedly and pivot through connected systems. The longer the lifetime, the larger the window for abuse and the harder it is to prove containment.
Q: How do security teams know if NHI controls are actually working?
A: Look for complete inventory coverage, clear ownership, enforced rotation, and evidence that unused credentials are removed on time. If secrets remain active after changes to applications, vendors, or pipelines, the control is not working. Monitoring should also show whether machine access stays within the expected workload scope.
Q: What should teams do when a former employee may have left active NHI credentials behind?
A: Treat the situation as an identity offboarding issue, not just a personnel issue. Reconstruct which tokens, service accounts, and keys were created for that work, verify ownership, revoke anything unnecessary, and rotate any credential that must remain in service under a current owner.
Technical breakdown
Why idle secrets stay dangerous after workloads stop using them
An idle secret is still an authentic credential until it is rotated, expired, or revoked. That means a token, API key, or service account can sit outside normal operational attention while still granting access to production systems. In distributed environments, secrets are copied into CI/CD pipelines, microservices, and vaults, so one stale credential can outlive the workload that originally depended on it. The technical risk comes from persistence, not activity: a credential does not need to be used frequently to remain exploitable. If it is valid, an attacker who finds it can authenticate immediately and blend in as legitimate traffic.
Practical implication: inventory and lifecycle state matter more than observed usage alone for NHI credential risk.
How long-lived secrets create undetected access paths
When secrets do not expire, detection logic loses a natural boundary. Traditional monitoring often expects logins, session creation, or human workflow events, but NHIs do not behave like users and may operate silently for long periods. A forgotten service account can keep its entitlements even after the business process changes, which is why privilege creep appears faster in machine identity estates than in human IAM. The result is a standing access path that can be used for lateral movement, data access, and workflow manipulation without triggering the cues many SOC processes rely on. The control gap is not simply missing alerts. It is missing lifecycle termination.
Practical implication: pair behavioural monitoring with expiry and revocation controls so access cannot persist indefinitely.
Why offboarding logic must extend to service accounts and tokens
Offboarding is often built around employees, but the same lifecycle problem applies to the NHIs they create or own. If a departing engineer leaves behind API keys, service accounts, or automation tokens, the identity may remain valid even after the person is gone. That leaves ownership detached from privilege, which is a classic governance failure in NHI programmes. The article also shows why expiration policies and metadata such as last usage and creation time are operationally important: without them, teams cannot tell whether a secret is active, stale, or abandoned. In practice, the issue is incomplete decommissioning of access, not just poor housekeeping.
Practical implication: treat NHI offboarding as a required lifecycle event for credentials, not only for people.
Threat narrative
Attacker objective: The attacker aims to use forgotten but still-valid NHI credentials to maintain durable access and extract or alter sensitive systems and data over time.
- Entry occurs when attackers obtain an idle API key, token, or service account that is still valid but no longer monitored.
- Credential abuse follows because the secret remains authenticated and can be used without password resets, MFA challenges, or approval gates.
- Escalation and lateral movement become possible as the attacker reuses standing privileges across environments and discovers additional access paths.
- Impact accumulates through persistent unauthorized access, data theft, workflow disruption, and long-lived exposure that can last months or years.
Breaches seen in the wild
- Hugging Face Spaces breach 2024: Unauthorised access to Hugging Face Spaces may have exposed secrets users stored for AI apps; tokens were revoked and org tokens removed.
Read our 52 NHI Breaches Analysis report for a comprehensive view of breaches impacting Non-Human Identities including AI Agents.
NHI Mgmt Group analysis
Idle secret debt is a lifecycle failure, not a visibility problem: Secrets that remain valid after use stops create a hidden access estate that traditional human-centric IAM processes do not close down. The central issue is that ownership, expiration, and revocation are not being enforced at the point where machine access becomes obsolete. That turns unused credentials into standing risk rather than dormant inventory. Practitioners need to treat unresolved lifecycle state as exposure, not backlog.
Long-lived NHI access converts rare compromise into durable compromise: A secret that never expires gives an attacker more time than most monitoring and response processes can reasonably assume. The article's 40% idle-secret figure shows that this is not an edge case but a common operating condition in distributed environments. Once the credential is obtained, the window for detection is measured in months, not minutes. Teams should view duration of validity as a primary risk variable.
NHI lifecycle governance is now a control plane for blast-radius reduction: In estates where secrets are copied across CI/CD, vaults, and service integrations, the decisive question is no longer whether a credential exists, but whether anyone can prove it should still exist. That makes inventory accuracy, expiry policy, and revocation discipline the real boundary controls. The practitioner takeaway is simple: if a secret can outlive its business purpose, the governance model is already behind the threat model.
Offboarding must include machine-owned access, not just departed people: The article shows how former employees can leave behind active credentials, but the deeper problem is that many organisations still offboard humans while leaving their NHIs behind. That means the access relationship survives the owner. Governance teams should therefore measure offboarding completeness by credential termination, not employment status alone.
Idle-secrets drift is the new privilege creep: Privilege creep used to describe users accumulating access over time; now stale programmatic access does the same thing at machine speed. As environments scale, the danger is not only overpermissioned NHIs but forgotten ones that remain both overpowered and invisible. The practitioner conclusion is that lifecycle controls must be continuous, because the attack surface is continuously expanding.
From our research library:
- 1 in every 1,000 non-human identities in enterprise environments is more than 10 years old.
- Read next: Guide to NHI Rotation Challenges
What this signals
Idle secret debt: credentials that stay valid after use ends create a hidden access layer that normal user-focused controls will not close. Security teams should measure how many NHI credentials can still authenticate without an active business purpose, because the real risk is duration of validity, not frequency of use.
The governance shift is from detecting misuse after the fact to proving that stale machine access cannot persist in the first place. That means inventory accuracy, expiry enforcement, and offboarding discipline now matter as much as monitoring.
For broader identity context, the ratio of NHIs to human identities continues to make lifecycle control harder at scale, according to the Ultimate Guide to NHIs. That scale makes stale credential discovery a programme issue, not a one-off clean-up task.
For practitioners
- Implement secret expiration by default Require API keys, tokens, certificates, and service account credentials to expire automatically unless a documented exception is approved and reviewed.
- Track NHI creation, use, and ownership metadata Maintain an inventory that records creation time, last used time, owner, and business purpose so idle credentials can be identified before they become liabilities.
- Extend offboarding to machine credentials Add revocation and rotation steps for service accounts, tokens, and automation keys whenever the human owner leaves or the workload is retired.
- Set shorter rotation windows for high-impact secrets Prioritise secrets with broad access to production systems, vaults, or deployment pipelines and rotate them more frequently than low-risk credentials.
- Alert on unused credentials before they become dormant Trigger investigation when a secret has not been used for a configurable period such as 30 days, then validate whether the credential is still needed.
Key takeaways
- Idle NHI secrets remain dangerous because they stay valid after the business use case disappears, creating standing access for attackers.
- The source article reports that 40% of identified secrets are idle, which shows this is a common lifecycle problem rather than an edge case.
- The control that limits the damage is lifecycle discipline: expire, rotate, revoke, and offboard machine credentials before they become permanent attack surface.
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 MITRE ATT&CK address the attack and risk surface, while NIST SP 800-53 Rev 5 and CIS Controls v8 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-01 — Improper Offboarding | The article centers on credentials left active after their owners or workloads are gone. |
| NHI-07 — Long-Lived Secrets | Idle secrets stay usable for months or years, which is the core risk described here. | |
| NHI-05 — Overprivileged NHI | Stale credentials often retain more access than the current use case requires. | |
| Recommendation — Revvoke and archive machine credentials when the owning workload or employee is retired. Replace indefinite credential validity with explicit expiration and rotation policy. Review NHI entitlements periodically and reduce any access that exceeds current business need. | ||
| NIST SP 800-53 Rev 5 | IA-5 — Authenticator Management | IA-5 governs authenticator lifecycle, including rotation and revocation of machine credentials. |
| Recommendation — Apply authenticator management to enforce rotation, expiry, and revocation for NHI secrets. | ||
| CIS Controls v8 | CIS-5 — Account Management | The article is fundamentally about unmanaged accounts and credentials that persist beyond need. |
| Recommendation — Maintain an accurate account inventory and remove stale machine identities quickly. | ||
| MITRE ATT&CK | TA0006;TA0008 — Credential Access; Lateral Movement | Idle secrets enable credential access and allow attackers to move across systems with standing access. |
| Recommendation — Map idle-secret exposure to credential access and hunt for lateral movement opportunities. | ||
Key terms
- Idle Secret: An idle secret is a credential that remains valid even though the system or process that uses it is no longer active. These secrets often persist because they are forgotten, unrotated, or left without ownership, creating a quiet but durable access path for attackers.
- NHI Sprawl: The uncontrolled growth of non-human identities such as service accounts, API keys, OAuth clients, and machine roles. It becomes a governance problem when ownership, purpose, rotation, and decommissioning are unclear, leaving dormant credentials active long after their original use case ends.
- Secret Lifecycle Management: Secret lifecycle management is the practice of creating, rotating, expiring, revoking, and retiring credentials according to policy. It turns secret handling from a one-time setup task into an ongoing governance process, which is essential when credentials are distributed across cloud, CI/CD, and automation environments.
- Vendor offboarding: Vendor offboarding is the controlled removal of a third party's access, data paths, and operational dependencies when the relationship ends or changes. It is a lifecycle control, not an administrative closeout, because any surviving credentials or integrations remain active security exposure.
Deepen your knowledge
NHI governance, agentic AI identity, and machine identity lifecycle are core topics in our NHI Foundation Level course, the industry's only accredited NHI security programme. If you are responsible for identity security strategy or NHI governance in your organisation, it is worth exploring.
Published by the NHIMG editorial team on May 12, 2026.
Updated on October 6, 2026.
NHI Mgmt Group, the independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org