Who is accountable for keeping microsegmentation aligned with changing clinical access and device inventory?

Accountability should sit jointly with network security, IAM, and the teams that own clinical applications and connected devices. Security defines the control model, IAM keeps identity and privilege data current, and system owners validate which communications are operationally required. Without shared ownership, policies drift and critical exceptions become permanent gaps.

Why This Matters for Security Teams

Microsegmentation is only effective when it reflects current clinical access patterns and the real device estate, not last quarter’s network diagram. In healthcare environments, that means accountability cannot sit with a single team alone. Network security may own the policy engine, but IAM must keep identity and privilege data current, while clinical application and biomedical device owners confirm what traffic is operationally required. This is especially important where shared workstations, roaming staff, managed service accounts, and connected devices blur traditional trust boundaries.

When ownership is unclear, exceptions outlive their justification and segmentation becomes a paper control. The result is either overblocking, which disrupts patient care, or underblocking, which leaves lateral movement paths open. Good governance also needs continuous change intake, because device replacements, application upgrades, and new clinical workflows can invalidate policy assumptions quickly. Guidance from NIST SP 800-53 Rev 5 Security and Privacy Controls supports clear control ownership and ongoing control assessment, but the operating model still has to be designed locally.

In practice, many security teams discover microsegmentation drift only after a blocked workflow or a suspicious east-west path has already exposed the gap.

How It Works in Practice

The most reliable model is a shared accountability loop. Network security defines segmentation zones, rule structure, and monitoring thresholds. IAM maintains authoritative sources for users, service accounts, non-human identities, and role changes. Clinical and device owners validate which endpoints, applications, and protocols are necessary for care delivery. Change management then ties those inputs together so policy updates happen when access or inventory changes, not after an incident review.

Operationally, teams should treat segmentation as a living control with a defined review cadence. That usually includes:

• an inventory of clinical devices, applications, and supporting services with named owners
• identity sources that track human, service, and machine access separately
• approval workflows for temporary exceptions with expiry dates
• telemetry that shows allowed, denied, and newly observed connections
• periodic recertification of both rule intent and business necessity

Where automation exists, it should support policy suggestion and drift detection rather than silently rewriting rules. That is particularly important for connected medical devices and vendor-managed systems, where maintenance windows, proprietary protocols, and safety constraints can make aggressive automation risky. Identity governance also matters for machine access. The OWASP Non-Human Identity Top 10 is useful here because many segmentation failures now involve secrets, service identities, or embedded credentials rather than only human users. These controls tend to break down when device ownership is undocumented, because no one is able to approve or retire the traffic exceptions that keep the policy accurate.

Common Variations and Edge Cases

Tighter segmentation often increases operational overhead, requiring organisations to balance stronger isolation against clinical uptime and support complexity. In hospitals, the right answer is not always maximum restriction. Emergency access, vendor support channels, and legacy devices may require controlled exceptions, but current guidance suggests those exceptions should be explicitly owned, time-bound, and reviewed.

There is no universal standard for exactly how much segmentation should be enforced around imaging systems, bedside devices, or building management networks. Best practice is evolving toward risk-based zoning, where high-value clinical systems get stronger boundaries and low-risk support assets remain in separate segments. Shared responsibility also becomes harder when outsourced IT or biomedical vendors manage parts of the environment, because ownership of policy intent, inventory accuracy, and exception approval can fragment across contracts.

The practical test is simple: if the team cannot say who approves a rule, who validates the asset behind it, and who removes it when the device or workflow changes, the segmentation model will drift. Accountability should therefore be written into the operating model, not left implicit in a ticket queue.

Related resources from NHI Mgmt Group

• Who is accountable for keeping access changes aligned when employees change roles?
• Who is accountable for keeping access rights aligned with policy and compliance requirements?
• How should security teams run access reviews for non-human identities?
• How should security teams govern non-human identities that have persistent access?