Third-party services increase risk because they extend trust beyond the organisation’s own perimeter and can introduce weak controls, inherited access, and compromised accounts. Shared credentials make it harder to attribute activity, rotate access cleanly, and contain incidents. A strong response is to minimise standing access, use unique credentials, and monitor vendor connections continuously.
Why This Matters for Security Teams
Third-party services and shared credentials widen the blast radius because they turn one control failure into many. A vendor account, integration token, or reused login can become a bridge into production systems, cloud consoles, and data pipelines. The issue is not just exposure, but inherited trust: once access is shared, it becomes harder to prove who acted, what they touched, and whether the activity was legitimate.
That is why NHIMG’s 2024 ESG Report: Managing Non-Human Identities matters here. It found that 72% of organisations have experienced or suspect a breach of non-human identities, which shows how often hidden service access becomes the path of least resistance. This is consistent with the guidance in the OWASP Non-Human Identity Top 10, which treats unmanaged NHI credentials as a core attack surface rather than an edge case.
Security teams often underestimate how quickly attackers move once third-party access or shared secrets are exposed. In practice, many security teams encounter vendor abuse only after suspicious activity has already blended into normal service traffic.
How It Works in Practice
Risk rises when external services are granted durable access, especially through long-lived API keys, shared passwords, or over-privileged service accounts. These credentials are often copied into CI/CD systems, ticketing tools, scripts, and partner integrations, which multiplies exposure. If the same secret is used by multiple operators or workloads, attribution becomes weak and revocation becomes disruptive.
Current guidance suggests treating each third-party connection as a distinct trust boundary. That means issuing unique credentials per service, scoping access narrowly, and preferring short-lived tokens over static secrets. NHIMG’s Ultimate Guide to NHIs, Static vs Dynamic Secrets reinforces the operational value of dynamic credentials, while the Guide to the Secret Sprawl Challenge shows why duplicated credentials are so difficult to inventory and contain.
In practice, effective controls usually include:
- Unique identity per vendor, tool, or workload, not one shared login for convenience.
- Just-in-time access for administrative actions, with automatic expiry after the task ends.
- Central logging that ties each request to a specific principal and purpose.
- Continuous monitoring of vendor connections, secrets exposure, and anomalous use patterns.
For teams formalising the control set, the NIST Cybersecurity Framework 2.0 supports stronger identity governance, while NIST SP 800-53 Rev 5 Security and Privacy Controls provides control families for access control, auditing, and configuration management. These controls tend to break down when partner systems require persistent machine-to-machine trust that cannot tolerate frequent credential rotation.
Common Variations and Edge Cases
Tighter third-party access often increases operational overhead, requiring organisations to balance faster integrations against stronger containment. That tradeoff becomes especially visible in managed service providers, SaaS plug-ins, and emergency support relationships, where teams may be tempted to reuse credentials to avoid service disruption.
There is no universal standard for this yet, but best practice is evolving toward context-aware access, service-specific identities, and short-lived authorization rather than broad standing permissions. Where shared credentials cannot be eliminated immediately, organisations should segment their use, wrap them in privileged access workflows, and treat them as high-risk exceptions rather than normal operating practice.
This is also where breach pattern analysis helps. NHIMG’s 52 NHI Breaches Analysis is useful for showing how compromised service identities often sit inside larger compromise chains, not as isolated events. The practical lesson is simple: the more parties that know a secret, the less control any one team has over its use, rotation, and containment.
Vendor access is hardest to secure in legacy environments with flat networks, shared admin tooling, or brittle integrations that cannot tolerate per-service identity separation.
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 SP 800-63, NIST AI RMF and NIST Zero Trust (SP 800-207) set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-01 | Shared credentials and vendor access expand NHI attack surface. |
| NIST CSF 2.0 | PR.AC-4 | Third-party trust and least privilege are core access-management concerns. |
| NIST SP 800-63 | AAL2 | Stronger identity assurance reduces misuse of reused or shared access. |
| NIST AI RMF | GOVERN | Governance is needed to assign accountability for third-party identity risk. |
| NIST Zero Trust (SP 800-207) | PL-1 | Zero trust limits implicit trust in third-party connections and shared secrets. |
Inventory every third-party identity and replace shared secrets with unique, scoped service identities.
