Zero Trust vs. VPN for NHI governance and access control

At a glance

What this is: This is a practitioner comparison of Zero Trust and VPNs, with the core finding that continuous verification and granular access control better fit modern identity-driven environments.

Why it matters: It matters to IAM and NHI practitioners because VPN-style network trust can widen blast radius when service accounts, tokens, or privileged users are compromised.

👉 Read StrongDM's analysis of Zero Trust vs. VPN for access control

Context

Zero Trust and VPNs solve different access problems, but only one is designed around continuous identity verification. In NHI governance terms, the gap is straightforward: once machine and human access are treated as network membership instead of task-scoped entitlement, overexposure becomes the default.

StrongDM frames the issue around remote access and privileged access management, but the underlying security question is broader. Security teams are deciding whether they want persistent network reach or continuously evaluated resource access, which is why the comparison maps directly to NHI governance, least privilege, and Zero Trust operating models.

Key questions

Q: How should security teams govern NHIs in a Zero Trust architecture?

A: Security teams should govern NHIs by binding each machine identity to a specific task, resource, and time window. Continuous verification only works when service account ownership, credential lifecycle, and revocation are operational, because otherwise Zero Trust becomes a network label rather than an access control model.

Q: When does a VPN create more risk than it reduces?

A: A VPN creates more risk than it reduces when broad internal reach replaces resource-level authorization. If a compromised session can laterally access systems beyond the original task, the VPN is protecting transport but expanding the identity blast radius.

Q: What is the difference between Zero Trust and VPN for privileged access?

A: Zero Trust narrows privileged access to the specific request, while a VPN usually grants a broader network path after login. For privileged operations, the difference is whether access is continuously checked and time-bound or simply inherited for the life of the session.

Q: How can teams reduce blast radius for remote and machine access?

A: Teams can reduce blast radius by combining JIT access, PAM, and strong identity inventory. The goal is to ensure privileged access is approved for a short duration, tied to a named owner, and revoked automatically when the task ends.

Technical breakdown

How Zero Trust changes access decisions

Zero Trust shifts the control point from network entry to request-time authorization. Instead of trusting a device or user after initial authentication, the policy engine evaluates identity, device posture, resource sensitivity, and contextual risk on each request. That makes the access decision narrower and more dynamic, which matters when credentials can be reused across systems or stolen from automation pipelines. For NHIs, the model is especially relevant because service accounts and tokens rarely behave like stable human users. A Zero Trust design can enforce task-scoped access, but only if identity inventory, policy logic, and logging are all aligned.

Practical implication: Map NHI access to request-time policy checks, not just perimeter authentication.

Why VPNs create a larger identity blast radius

A VPN protects traffic in transit, but once a session is established it often grants broad internal reach. That model assumes the authenticated user or device remains trustworthy for the life of the connection, which is exactly where modern attacks exploit weakness. If a laptop, token, or automation host is compromised, the attacker inherits the network path rather than a tightly bounded entitlement. For NHIs, this matters because machine credentials are frequently long-lived and embedded in pipelines, scripts, or secrets stores. The result is a larger identity blast radius than many teams expect.

Practical implication: Treat VPN access as transport security, not as an entitlement model for NHIs.

How JIT access and PAM fit into Zero Trust architecture

Just-in-Time access and Privileged Access Management are control patterns that reduce standing exposure. JIT limits the duration of access, while PAM defines and monitors high-risk entitlements. In a Zero Trust architecture, those controls should work together so that privileged machine and human access is granted only for a specific task and then revoked automatically. That is particularly important for NHI workflows, where long-lived service credentials and broad operator permissions often coexist. The architecture fails when JIT becomes a manual exception process instead of an enforced access state.

Practical implication: Use JIT and PAM to shrink privileged exposure windows for both humans and NHIs.

Threat narrative

Attacker objective: The attacker’s objective is to turn one authenticated session into broad internal reach and then use that reach to access high-value systems.

1. Entry occurs when a compromised VPN session or reused credential grants broad internal network reach.
2. Escalation follows when the attacker moves from transport-level access to privileged internal systems through overbroad entitlements.
3. Impact occurs when the attacker uses that wide access path to reach sensitive resources faster than request-level controls could have stopped them.

Breaches seen in the wild

• Cisco DevHub NHI breach — IntelBroker exploited exposed Cisco credentials, API tokens and keys in DevHub.
• DeepSeek breach — DeepSeek breach exposed 1M+ log lines and sensitive secret keys.

Read our 52 NHI Breaches Analysis report for a comprehensive view of breaches impacting Non-Human Identities including AI Agents.

NHI Mgmt Group analysis

Zero Trust is now the more relevant governance model for NHIs because machine identities amplify the weakness of perimeter trust. Service accounts, API keys, and tokens do not fail like users do. They are embedded in automation and often reused across environments, so once a broad access path exists, the blast radius expands quickly. Practitioners should stop treating network entry as the primary control boundary and start treating each resource request as the unit of governance.

VPNs are still useful for transport protection, but they are a poor default for access governance. Encryption in transit does not equal entitlement minimisation. The discipline for NHI teams is to separate the need for secure connectivity from the need for authorization, because those are different control problems and they fail differently under compromise. The practical conclusion is to reserve VPNs for connectivity cases, not as the main access model.

Identity blast radius is the right concept for comparing these two architectures. The issue is not whether one tool is modern and the other is legacy. The issue is how much access an attacker inherits when a credential or session is compromised. Once practitioners measure access in blast radius rather than perimeter reach, least privilege becomes a design requirement instead of a policy aspiration.

Zero Trust only improves NHI governance when policy, inventory, and revocation are operationalised together. Continuous verification without accurate identity inventory just moves the blind spot. Teams need service account ownership, short-lived credentials, and revocation workflows that match the speed of automation. The governance lesson is clear: architecture alone does not close NHI risk unless lifecycle controls keep pace.

From our research:

• 97% of NHIs carry excessive privileges, increasing unauthorised access and broadening the attack surface, according to Ultimate Guide to NHIs.
• Only 20% of organisations have formal processes for offboarding and revoking API keys, and even fewer have procedures for rotating them, according to Ultimate Guide to NHIs.
• For a broader control baseline, see Ultimate Guide to NHIs , Standards for the frameworks that map Zero Trust and NHI controls into practice.

What this signals

Identity blast radius is becoming the most useful operating metric for access strategy. Once teams compare VPN and Zero Trust through the lens of how far a stolen session can travel, the governance gap becomes visible. For NHI-heavy environments, that means the priority shifts from connection establishment to scope, duration, and revocation speed.

The practical signal for security programmes is that transport security and access governance must be split into separate control planes. A protected tunnel does not reduce the risk created by over-privileged service accounts, and the 97% excessive-privilege figure in our research shows how common that failure mode already is. Teams should align policy, inventory, and lifecycle controls before they expand automation or remote access patterns.

Zero Trust programmes that do not account for machine identities will underperform in cloud and automation-heavy environments. The next control maturity step is to connect request-time policy enforcement to identity ownership and time-bound elevation, then validate those controls against actual NHI exposure.

For practitioners

• Implement request-level access decisions for NHIs Move service accounts, tokens, and operator access behind policy checks that evaluate resource sensitivity, identity, and context for each request.
• Limit privileged access with JIT and PAM Grant elevated access only for the task window, then revoke it automatically and log the approval path for audit and review.
• Separate transport security from authorization Use VPNs only where encrypted connectivity is required, and avoid treating network membership as proof of entitlement to internal resources.
• Inventory NHI credentials and session paths Track service accounts, API keys, certificates, and automation sessions so policy enforcement can be tied to real ownership and revocation.
• Align access reviews to blast radius Prioritise the NHIs and operator paths that can reach the most sensitive systems, then reduce standing exposure before expanding usage.

Key takeaways

• Zero Trust is a better governance fit than VPNs when the problem is controlling what an identity can reach, not just encrypting its traffic.
• NHIs make broad network access especially dangerous because machine credentials often outlive the task they were created for.
• Teams should measure access in terms of blast radius, then use JIT, PAM, and revocation workflows to shrink it.

Key terms

• Identity Blast Radius: The amount of access an attacker gains after compromising one credential, session, or account. In NHI environments, blast radius is shaped by credential scope, privilege breadth, and how quickly access can be revoked when something looks wrong.
• Request-Level Authorization: An access model that evaluates each request against policy before allowing it to proceed. For NHIs, this means entitlement is tied to the specific resource, context, and time window instead of being assumed from a network connection or prior login.
• Just-In-Time Access: A control pattern that grants elevated access only for a narrow task window and removes it automatically afterward. It is especially important for NHIs because temporary access reduces the exposure created by long-lived service credentials and reusable automation paths.
• Privileged Access Management: The discipline of controlling, monitoring, and limiting high-risk access to sensitive systems. For NHIs, PAM is most effective when it covers service accounts, automation identities, and human operators with the same revocation and audit discipline.

Deepen your knowledge

Zero Trust, privileged access, and NHI lifecycle governance are core topics in our NHI Foundation Level course, the industry's only accredited NHI security programme. If your team is moving from perimeter access to request-level control, it is worth exploring.

This post draws on content published by StrongDM: Zero Trust vs. VPN: What Solution Is Right for You? Read the original.