Why do third-party users and supply chain partners create such a large compliance and security risk in utilities?

Third-party users increase risk because they extend trust outside the utility’s direct control while still reaching protected environments. If their sessions, software, or credentials are not verified and governed, attackers can use them to alter systems, move through the network, or hide activity. That is why supply chain risk management and identity verification are central to these controls.

Why third-party access becomes a utility risk multiplier

Utilities rarely fail because a third party is present. They fail because third-party access often arrives with legitimate trust, broad reach, and weak observability. That combination matters in operational technology, enterprise IT, and vendor-managed platforms because an external user may still touch systems that are difficult to segment, monitor, or rapidly recover.

Once that access is allowed, the security question changes from “who is this user?” to “what can they reach, what can they change, and how quickly would we notice?” In practice, utilities have to treat every external session, token, integration, and remote support path as part of the attack surface.

Where the compliance burden comes from

Third parties create compliance pressure because the utility remains accountable even when the activity is performed by a contractor, supplier, integrator, or managed service provider. Auditors and regulators usually care less about who owns the account and more about whether access was approved, limited, logged, reviewed, and revoked on time.

That is why vendor access governance, identity proofing, segregation of duties, and evidence retention become so important. A utility needs to show that external access is granted for a defined purpose, constrained to a defined scope, and removed when the work ends. The strongest controls are the ones that make the access decision visible and repeatable rather than informal.

Utilities also face a documentation problem: supply chain partners often use their own tools, their own support processes, and sometimes their own credentials. If those pathways are not contractually and technically controlled, the utility may not be able to prove who performed an action, which system was used, or whether a privileged session was recorded.

Why attackers target third-party relationships

Third-party users are attractive because they can provide a faster path into protected environments than a direct attack against the utility itself. If a vendor account is overprivileged, reused across clients, or protected by weak authentication, one compromise can become a foothold into multiple systems. The same issue applies to software and integration partners: if their tokens, secrets, or update channels are exposed, the attacker may inherit trusted access rather than having to break in from scratch.

The highest-risk cases usually involve access that is both trusted and persistent. Long-lived credentials, standing access, and remote administrative tools create opportunities for abuse, lateral movement, and delayed detection. That is why utilities need to verify not only the third party’s identity, but also the provenance of the software, the scope of the integration, and the lifecycle of the access itself.

For a practical view of how external trust chains fail, see Klue OAuth Supply Chain Breach, Reviewdog GitHub Action supply chain attack, and Cloudflare Breach. These cases show the same pattern: trusted access plus weak credential hygiene creates disproportionate blast radius.

What utilities should verify before trusting third-party access

The control objective is not to eliminate third parties. It is to make their access bounded, attributable, and revocable. That means the utility should verify the identity of the external user or service, confirm the business justification, limit the permissions to the minimum required, and tie the access to a clear owner on the utility side.

Utilities should also verify the non-technical conditions that usually get overlooked: contract terms, incident notification duties, log access, remote support windows, and offboarding triggers. If the third party can still authenticate after the work is complete, the access model is already failing. If the utility cannot detect or review the third party’s activity, the control is only partially real.

Modern third-party risk management is strongest when identity controls, supply chain review, and session governance are handled together. The OWASP Non-Human Identity Top 10 is especially useful here because many supplier connections depend on tokens, service accounts, and integrations rather than human logins. For supply chain integrity, NIST SSDF (SP 800-218) and SLSA help frame software provenance and build trust. For broader third-party governance in regulated environments, EU Digital Operational Resilience Act (DORA) is a strong reference point.

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 addresses the attack surface, NIST SP 800-53 Rev 5, CIS Controls v8 and CSA Cloud Controls Matrix set the technical controls, and EU AI Act defines the regulatory obligations.

Framework	Control / Reference	Relevance
OWASP Non-Human Identity Top 10	NHI-05 — Overprivileged NHI	Third-party access often becomes risky through excessive permissions and broad trust.
	NHI-02 — Secret Leakage	Supplier integrations and tokens are common paths for credential exposure and abuse.
	NHI-07 — Long-Lived Secrets	Persistent vendor credentials increase the blast radius of compromise and delayed revocation.
Recommendation — Restrict supplier access to the minimum privileges needed for each approved task. Protect and rotate third-party secrets so exposed tokens cannot be reused for access. Replace persistent supplier credentials with short-lived access and strict expiry.
NIST SP 800-53 Rev 5	AC-20 — Use of External Information Systems	External users and partners accessing utility systems map directly to controlled external system use.
	IA-2 — Identification and Authentication (Organizational Users)	Utilities need strong authentication for externally operated accounts and sessions.
	IA-5 — Authenticator Management	Third-party risk often comes from poor lifecycle control of credentials and tokens.
Recommendation — Authorize and constrain external access paths before allowing supplier connectivity. Require strong authentication for every third-party user account that reaches utility systems. Manage supplier credentials with issuance, rotation, revocation, and expiration controls.
CIS Controls v8	CIS-6 — Access Control Management	Third-party users create access governance and least-privilege problems.
Recommendation — Centralise third-party access approvals, reviews, and revocation under access control management.
CSA Cloud Controls Matrix	IAM — Identity and Access Management	Cloud and managed-service third parties require governed identity and access controls.
	GRC — Governance, Risk and Compliance	Utilities must evidence third-party controls for compliance and assurance.
Recommendation — Apply IAM controls to external users, integrations, and service accounts with utility reach. Document third-party accountability, review cycles, and exception handling for audit readiness.
EU AI Act	UNKNOWN — AI supply chain and governance obligations	Only the supplied material references AI-related supply chains, so this remains a discovery candidate.
Recommendation — Omit from production mapping until a specific article-level control can be validated.

Practitioner Guidance

What to prioritise: Start with external access that can reach production, operational technology, or shared administrative tooling. Those paths deserve the most scrutiny because they combine privilege, reach, and weak attribution.

What to verify: Confirm that every third-party account has a named owner, a defined expiry or review date, and logs that show what was accessed. If the utility cannot evidence those three items, it is relying on trust rather than control.

Decision rule: If a supplier needs ongoing access to perform support, treat that as a privileged access problem, not a procurement issue. Move it into formal access governance, because contract language alone does not reduce technical exposure.

Practitioner takeaway: The real risk is not third-party involvement itself, but third-party trust that outlives the business need, exceeds the minimum necessary privilege, or cannot be independently verified.