They create long-lived machine trust that is often outside normal identity lifecycle controls. If a supplier certificate or service token is not owned, monitored, and rotated, attackers can reuse it long after the original business context has changed. That turns external access into persistent exposure, especially when the supplier connects to sensitive customer environments.
Why This Matters for Security Teams
Third-party certificates and credentials often sit in a blind spot because they are issued for systems, not people, and they may never pass through the same review, approval, or offboarding steps as workforce access. That makes them easy to overlook until a supplier connection is abused to move into a customer environment. The issue is not only theft. It is also ownership drift, weak rotation discipline, and unclear accountability across organisations. The NIST Cybersecurity Framework 2.0 is useful here because it frames identity and access as an operational control problem, not just a policy statement.
For security teams, the practical risk is that a certificate can remain trusted long after the business relationship, endpoint, or integration has changed. A token issued for a narrow automation task can later become a standing route into sensitive workloads if no one owns its lifecycle. This is especially dangerous in supply chain scenarios where the external party has legitimate reach into production, data exchange, or privileged administration. In practice, many security teams encounter third-party abuse only after a supplier credential has already been reused outside its original purpose, rather than through intentional lifecycle governance.
How It Works in Practice
Mismanaged machine credentials increase breach risk because they create durable trust that is hard to see and harder to revoke quickly. Certificates, API keys, service tokens, and SSH keys are often embedded in code, stored in build pipelines, or distributed across multiple teams. Once issued, they may outlive the contract, the asset, or the person who requested them. That makes them materially different from interactive user logins, which are usually covered by joiner-mover-leaver processes and periodic access review.
Good practice is to treat these secrets as governed assets with clear ownership, expiry, telemetry, and revocation paths. The OWASP Non-Human Identity Top 10 is directly relevant because it highlights the same failure pattern: non-human identities accumulate without lifecycle controls, and attackers target the weakest links in that trust chain. In mature environments, teams typically:
- assign a named business and technical owner for each certificate or token;
- set short validity periods and automate renewal or replacement;
- log issuance, use, and revocation events into SIEM workflows;
- scan code, repositories, and pipelines for exposed secrets;
- tie third-party access to contractual scope and environment boundaries;
- test emergency revocation so compromised credentials can be invalidated quickly.
Monitoring matters because stolen credentials often do not trigger obvious anomalies. A supplier token may look legitimate even while being used from a new location, at a new time, or against a new workload. That is why detection has to combine entitlement context, asset criticality, and behaviour baselines. Current guidance suggests pairing secrets hygiene with zero trust principles and periodic supplier assurance, rather than relying on perimeter segmentation alone. These controls tend to break down when credentials are shared across multiple environments because revocation becomes operationally risky and teams delay action.
Common Variations and Edge Cases
Tighter credential governance often increases operational overhead, requiring organisations to balance stronger security against integration complexity and supplier friction. That tradeoff is real, especially where legacy systems or managed service providers rely on long-lived certificates for availability. Best practice is evolving, and there is no universal standard for every certificate type, but the direction is clear: reduce standing trust wherever possible and make exceptions explicit.
Edge cases usually appear in high-availability systems, manufacturing integrations, and regulated third-party services where immediate rotation is difficult. In those environments, organisations may need compensating controls such as network segmentation, certificate pinning, device attestation, and tighter monitoring of non-human identities. The risk is amplified when machine credentials are stored in shared vaults without per-application ownership, or when third parties can reissue their own secrets without customer visibility. The NIST SP 800-53 Rev 5 Security and Privacy Controls provides a useful control baseline for access enforcement, auditability, and system integrity, while the Anthropic first AI-orchestrated cyber espionage campaign report is a reminder that automated abuse increasingly depends on harvested credentials and trusted tools. Where agentic automation is involved, the line between normal machine access and attacker-controlled action can become very thin.
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 address the attack and risk surface, while NIST CSF 2.0, NIST AI RMF, NIST SP 800-63 and NIST SP 800-53 Rev 5 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI lifecycle and secret management | Non-human identities are the core risk surface for mismanaged machine credentials. |
| NIST CSF 2.0 | PR.AC, PR.PS, DE.CM | Access control, platform safeguards, and monitoring reduce third-party credential abuse. |
| NIST AI RMF | If AI agents or automation use third-party secrets, governance and accountability become critical. | |
| NIST SP 800-63 | AAL/IAL lifecycle principles | Identity assurance concepts help distinguish issued trust from active, verified use. |
| NIST SP 800-53 Rev 5 | IA-5, AC-2, AU-2 | Credential management, account lifecycle, and audit logging directly address this breach path. |
Control credential issuance, account use, and audit evidence so third-party access can be revoked and traced.
