Direct network access expands the blast radius of a compromised vendor account. If credentials are stolen or a partner is breached, an attacker can reach more of the internal environment than necessary and pivot beyond the intended application. Zero Trust network access is designed to reduce that exposure by limiting access to specific applications rather than the whole network.
Why VPN-Style Remote Access Creates a Larger Blast Radius
VPN-style access treats the remote party as if it has reached the network boundary, which is a very different trust model from application-scoped access. If a vendor account, token, or endpoint is compromised, the attacker may inherit broad reach into internal segments, not just the one service the partner was meant to use. That increases lateral movement opportunities and makes one credential more valuable to an attacker.
By contrast, zero trust network access is built to make access decisions around the user, device, and application request rather than the network itself. In practice, that means the partner should reach only the target application or workflow, not the full internal route space. The difference matters most when third parties are involved, because third-party compromise is common enough that the access model should assume eventual credential or endpoint failure.
For a healthcare organisation, the operational issue is not only “can the partner connect”, but “how far can that connection travel if the partner is breached?” A network-level tunnel can expose internal services, administrative paths, and adjacent systems that the partner never needed. An application-centric model narrows the reachable surface and reduces the chance that one external compromise becomes an environment-wide event. NHIMG’s Remote Access Identity Guide and Third-Party, B2B and Contractor Access Guide both frame this as a governance problem as much as a connectivity problem.
What Changes in the Attack Path When Access Is Network-Wide
With VPN-style remote access, the first compromised secret often becomes the starting point for discovery, reconnaissance, and pivoting. An attacker does not need to break the protected application directly if the tunnel exposes shared internal services, management ports, or poorly segmented east-west paths. That is why remote access without strong restriction can turn a partner incident into a broader intrusion.
Zero trust network access changes the attack path by forcing per-application policy enforcement and reducing implicit trust in the connection. Even if a vendor account is stolen, the attacker should encounter smaller reachable scope, stronger verification, and more opportunities for denial before they can move laterally. This is the same trust-boundary logic behind NIST SP 800-207 Zero Trust Architecture and NHIMG’s Zero Trust Identity Guide.
The practical distinction is important in healthcare because partner access often exists to support billing, diagnostics, imaging, claims, device support, or SaaS administration. Those workflows rarely require broad network reach. If the access path is wider than the job function, the organisation is paying for convenience with unnecessary exposure.
How to Judge Whether the Remote Access Model Is Too Permissive
Ask whether the third party needs a network path or just a controlled path to a specific application, API, or admin console. If the answer is the latter, VPN-style access is usually too permissive for the risk being accepted. The more sensitive the internal environment, the more important it is to remove standing network reach and to treat each external connection as a bounded exception rather than a general entitlement.
The best indicator of over-permission is when a vendor account can see more of the environment than the vendor can operationally justify. If a compromise would let that party enumerate internal subnets, touch multiple systems, or reach shared infrastructure, the access design has already exceeded the business need. NHIMG’s IAM and IGA Basics is useful here because it ties access scope, entitlements, and lifecycle governance back to the real business requirement.
For healthcare teams, the most defensible pattern is to tie third-party connectivity to named applications, strong authentication, device and posture checks where possible, short-lived access, and explicit offboarding. That model reduces the chance that a vendor breach becomes an internal containment failure rather than a single-application incident.
Risk and Threat Considerations
VPN-style third-party access increases exposure because one stolen vendor credential can become a broad internal foothold. In healthcare, that creates a higher chance of lateral movement into sensitive systems, operational disruption, and spillover from a partner compromise into the provider’s own environment.
Failure mechanism: The remote session is trusted at the network layer, so compromise of the partner account, endpoint, or token can expose more internal routes than the vendor actually needs. Once inside, an attacker can probe for services, management interfaces, or shared trust paths that were never intended to be externally reachable.
Impact: The result is a larger blast radius, slower containment, and a greater chance that one third-party breach affects multiple internal services. In regulated healthcare environments, that can translate into data exposure, service interruption, and a much harder incident response problem.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
NIST Zero Trust (SP 800-207), NIST SP 800-53 Rev 5 and CIS Controls v8 set the technical controls, while ISO/IEC 27001:2022 defines the regulatory obligations.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST Zero Trust (SP 800-207) | PR.AA-05 — Least Privilege | Per-app access and reduced trust fit ZTNA's least-privilege model. |
| Recommendation — Limit third-party access to the specific applications and sessions they need. | ||
| NIST SP 800-53 Rev 5 | AC-6 — Least Privilege | Broad VPN access conflicts with least-privilege access control for third parties. |
| Recommendation — Restrict external access to the minimum set of resources required. | ||
| CIS Controls v8 | CIS-6 — Access Control Management | Third-party remote access needs tightly managed entitlements and revocation. |
| Recommendation — Inventory and revoke unnecessary external access paths promptly. | ||
| ISO/IEC 27001:2022 | A.5.15 — Access control | Remote access for third parties is an access-control decision requiring scope limits. |
| Recommendation — Define and enforce application-scoped access rules for external users. | ||
Practitioner Guidance
What to prioritise: Move third-party access decisions from “can they reach the network” to “which exact application or workflow do they need.” If a partner only needs one business function, do not preserve broad tunnel access for convenience.
What to verify: Check whether every third-party connection is mapped to a business owner, an application owner, and a revocation path. If you cannot quickly identify who can disable the access and what it is supposed to reach, the control is too weak to trust.
Common mistake: Treating VPN replacement as a cosmetic tooling change instead of an access-model change. If the trust boundary stays network-wide, the organisation has only modernised the wrapper, not reduced the risk.
Practitioner takeaway: For third parties, the real security gain comes from shrinking what a compromise can reach, not from changing the remote access product name.
Related resources from NHI Mgmt Group
- What happens when organisations rely on broad network access instead of Zero Trust for systems that process personal data?
- What breaks when organisations allow third parties broad network access instead of least privilege?
- How should organisations connect logical access and network access in a zero trust design?
- What happens when organisations use cloud applications and remote access without zero trust controls?
