Zero Trust Architecture Planning

HICP Practice 5.9 requires you to plan and implement Zero Trust Architecture (ZTA) principles in your network environment: micro-segmentation, continuous verification of access, and least-privilege network access ¹. Operationalize it by defining a ZTA target state, scoping “protect surfaces,” enforcing identity-based access, segmenting high-risk pathways, and retaining evidence that controls work.

Key takeaways:

• ZTA planning is a documented architecture change program, not a single tool purchase ¹.
• Auditors will look for implemented segmentation, continuous verification, and enforced least privilege at the network layer, plus proof of ongoing governance ¹.
• Start with high-value clinical and patient-data flows, then expand segmentation and policy enforcement across the enterprise ¹.

Zero trust architecture planning becomes real for a CCO or GRC lead when it turns into (1) a clear scope, (2) enforceable network access rules tied to identity and device posture, and (3) evidence that the environment actually blocks what it should. HICP Practice 5.9 sets a direct expectation: you must plan and implement zero trust principles, explicitly including micro-segmentation, continuous verification, and least-privilege network access ¹.

For most healthcare organizations and health IT vendors, the operational challenge is sequencing. You cannot segment everything at once without breaking clinical workflows, third-party integrations, and legacy medical devices. A credible program starts by mapping the “protect surfaces” (EHR, patient identifiers, medication systems, revenue cycle, identity providers), documenting how traffic should flow, then enforcing policy with staged controls. This page gives requirement-level implementation guidance you can hand to your network and security engineering teams, plus the governance and evidence package you’ll need for internal audit, external assessments, and customer due diligence.

Regulatory text

Requirement (HICP Practice 5.9): “Plan and implement zero trust architecture principles including micro-segmentation, continuous verification, and least-privilege network access.” ¹

What the operator must do

• Plan: Document a target architecture and implementation roadmap that explains where and how you will apply micro-segmentation, continuous verification, and least-privilege network access. The plan needs scope, priorities, owners, and decision points tied to risk.
• Implement: Put technical controls into production that enforce segmentation boundaries, verify access continuously (not only at login), and restrict network access to what is required for the role, system, or workload ¹.

Plain-English interpretation

HICP 5.9 expects you to stop treating your internal network as “trusted.” Every connection that reaches sensitive systems should be explicitly allowed, authenticated/authorized, and limited to the minimum required path. Practically, that means:

• You can explain (and enforce) which systems can talk to which systems, on which ports, under what conditions.
• Access decisions are based on identity and context (user identity, service identity, device status, location, workload), not just “it’s on the corporate LAN.”
• You can show that segmentation and least privilege exist at the network layer, not only in application permissions ¹.

Who it applies to

Entity types

• Healthcare organizations
• Health IT vendors ¹

Operational contexts where auditors expect this to show up

• Environments handling patient data and clinical operations (EHR ecosystems, PACS/imaging, lab systems, medication systems, identity platforms).
• Hybrid infrastructure: on-prem data centers, cloud workloads, and SaaS with site-to-site connectivity.
• Remote access pathways: VPN alternatives, third-party support access, managed service provider access, and clinician access from non-corporate networks.
• Flat or “mostly flat” networks with broad east-west connectivity, especially where legacy devices exist.

What you actually need to do (step-by-step)

1) Establish governance and scope that engineering can execute

• Assign a ZTA program owner (security architecture or network security) and a GRC owner accountable for evidence quality.
• Define the in-scope environments: start with your highest-risk systems and the network segments that reach them.
• Set decision criteria for exceptions (e.g., legacy medical devices that cannot support modern controls). Require compensating controls and an end-state plan.

Output: ZTA program charter, scope statement, exception process.

2) Define “protect surfaces” and map critical flows

Instead of trying to segment everything, pick protect surfaces tied to business impact:

• EHR and supporting databases
• Identity providers (IdP), MFA, privileged access systems
• File shares that store regulated data
• Clinical device management networks
• Payment/revenue cycle systems

Then map:

• User-to-app flows (clinicians, billing, support)
• App-to-app flows (interfaces, HL7/FHIR gateways, batch jobs)
• Admin/support flows (IT admin, third-party support)

Output: Data flow diagrams, system inventories with criticality tags, list of allowed flows (“policy intent”).

3) Translate flows into enforceable micro-segmentation policy

Micro-segmentation means you build smaller trust zones and tightly control east-west traffic.

• Start by defining zones (by application, function, sensitivity, and dependency).
• Convert your “policy intent” into explicit allow rules. Default-deny is the goal, but many teams phase it in using monitor-mode before enforcement.
• Put special focus on:
  • Workloads that store sensitive data
  • Admin pathways (jump hosts, management subnets)
  • Integration engines and interface servers (often become over-permitted)

Implementation options (choose what fits your environment):

• Network segmentation with VLANs/VRFs and firewall policy.
• Host-based micro-segmentation agents for data center and cloud workloads.
• Kubernetes/network policies for containerized environments.

Output: Segmentation design, rule sets, change tickets, deployment record.

4) Implement continuous verification for network access

HICP calls out continuous verification; treat this as ongoing authentication and authorization checks, plus ongoing policy evaluation ¹.

• Enforce identity-aware access for admin access and sensitive apps (for example, access proxies, ZTNA, or strong VPN controls with MFA).
• Add device posture checks where feasible (managed device, encryption, patch level, EDR present).
• For service-to-service traffic, move toward service identity and short-lived credentials where your platform supports it.

Output: Access policy standards, conditional access rules, logs showing enforcement and decisioning.

5) Enforce least-privilege network access

Least privilege at the network layer means “only the minimum required routes/ports/protocols, only from approved sources, only for approved identities.”

• Define a standard for “minimum required” at each tier:
  • User segment to app segment
  • App segment to database segment
  • Admin segment to management interfaces
• Restrict lateral movement:
  • Block workstation-to-workstation where not needed
  • Limit SMB/RDP/SSH exposure
  • Tighten management plane access (hypervisors, backups, directory services)

Output: Network access standards, firewall reviews, periodic rule recertifications.

6) Validate and monitor (prove it works)

Auditors do not accept “we designed it.” You need proof the environment enforces segmentation and access control.

• Run validation testing:
  • Attempted connections that should fail (blocked flows)
  • Allowed flows that must continue for clinical operations
• Monitor continuously:
  • Alerts for policy violations
  • Drift detection (new rules, widened rules, shadow IT pathways)
• Tie change management to segmentation and access policy updates.

Output: Test plans/results, monitoring dashboards/screenshots, alert samples, change records.

Required evidence and artifacts to retain

Keep artifacts in a form you can hand to an assessor quickly:

Planning and governance

• ZTA strategy/roadmap and target architecture ¹
• Scope definition and protect surface list
• Risk assessment or rationale for sequencing
• Exception register with approvals and compensating controls

Implementation

• Network segmentation diagrams (current and target)
• Firewall/micro-segmentation policy exports or rule inventories
• Identity and access policies supporting continuous verification (conditional access, MFA enforcement)
• Configuration baselines for critical enforcement points

Operational proof

• Change tickets for segmentation/access policy changes
• Validation test results (blocked/allowed flow testing)
• Logs showing enforcement decisions and denied connections
• Periodic reviews/recertifications of network access rules

Common exam/audit questions and hangups

Expect these, and pre-build the answers:

1. “Show me your zero trust plan.”
   They want a dated document with owners, scope, milestones, and a target state, not a slide with slogans ¹.

2. “Where is micro-segmentation implemented?”
   Be ready to point to specific environments (data center app tiers, cloud VPC segmentation, clinical device networks) and show enforced rules ¹.

3. “How do you continuously verify access?”
   Show conditional access policies, MFA enforcement for sensitive pathways, and log evidence that policy is evaluated over time ¹.

4. “How do you ensure least privilege at the network layer?”
   They will ask how rules are approved, who can change them, and how you prevent rule sprawl.

5. “What about third-party access?”
   Have a standard pattern (segmented access path, MFA, time-bound access, monitored sessions) and a documented exception path for emergencies.

Frequent implementation mistakes and how to avoid them

Mistake	What it looks like	How to avoid it
Treating ZTA as a product purchase	A ZTNA tool deployed for remote users, no internal segmentation changes	Anchor the program in protect surfaces and enforceable policy; tool choice comes after architecture
“Segmenting” only with diagrams	Pretty network maps, but broad any-any rules remain	Require rule inventory reviews and evidence of blocked flows
No dependency mapping	Clinical interfaces break after enforcement	Do flow discovery first; pilot in monitor-mode where possible
Weak exception control	Legacy systems get permanent any-any access	Time-box exceptions, require compensating controls, track remediation
Ignoring service identities	Apps still authenticate via shared credentials	Push service identity patterns in new builds; prioritize high-risk integrations

Enforcement context and risk implications

No public enforcement cases were provided in the available source catalog for this requirement. Even without enforcement examples, the risk is straightforward: flat networks and static trust assumptions increase the blast radius of credential theft, ransomware, and third-party compromise. HICP 5.9 is written to drive measurable reduction of lateral movement paths through segmentation, continuous verification, and least-privilege network access ¹.

Practical 30/60/90-day execution plan

Use this as an operator’s sequence. Adjust based on clinical change windows and outage tolerance.

First 30 days (Immediate)

• Publish ZTA charter, scope, and protect surfaces list ¹.
• Build system and data flow maps for the first protect surface (commonly the EHR and identity stack).
• Inventory segmentation enforcement points (firewalls, cloud security groups, host agents) and assess gaps.
• Define the exception process and start an exception register.

Day 31–60 (Near-term build)

• Implement segmentation for one protect surface using explicit allow rules.
• Enforce strong access controls for admin pathways (MFA, restricted management networks, approved jump access).
• Stand up validation testing (blocked/allowed flows) and logging to capture enforcement evidence.
• Start rule recertification workflow (owners, approvals, review cadence).

Day 61–90 (Expand and stabilize)

• Expand micro-segmentation to the next protect surface (clinical devices, revenue cycle, or integration layer).
• Add continuous verification enhancements (device posture checks where feasible, tighter third-party access controls).
• Formalize ongoing operations: policy change control, monitoring, drift detection, and exception burn-down reporting.
• Prepare an “audit packet” folder: plan, diagrams, rule inventories, tests, logs, and governance records.

Where Daydream fits naturally If you are coordinating ZTA planning across multiple business units and third parties, Daydream can help you centralize evidence collection (architecture documents, rule inventories, exception approvals), track control owners, and assemble an assessment-ready packet without chasing screenshots across teams.

Frequently Asked Questions

Does HICP 5.9 require a full enterprise zero trust rollout before we can say we comply?

The text requires you to “plan and implement” zero trust principles, including micro-segmentation, continuous verification, and least-privilege network access ¹. In practice, auditors accept phased implementation if you can show a credible plan, defined scope, implemented controls in priority areas, and tracked exceptions.

What counts as “micro-segmentation” for audit purposes?

Micro-segmentation means enforced boundaries inside your environment that limit east-west traffic to explicit allowed flows. Evidence is rule configurations and tests showing that prohibited connections fail and approved dependencies still work.

How do we show “continuous verification” without rebuilding every legacy app?

Start with the access pathways you control: admin access, remote access, and network gateways. Conditional access policies, MFA enforcement, device posture checks, and logs proving repeated policy evaluation are practical evidence ¹.

We have medical devices that can’t support modern security agents. What do we do?

Segment them into tightly controlled device networks, restrict inbound and outbound flows to required destinations, and document exceptions with compensating controls. Track a remediation plan tied to lifecycle replacement or compensating network controls.

How should we handle third-party support access under zero trust?

Provide third parties access through a segmented, identity-verified path with least-privilege rules and monitoring. Keep approvals, access logs, and evidence of time-bounded access for due diligence and audits.

What evidence is most persuasive to an assessor?

A dated ZTA plan, segmentation diagrams, rule inventories, and validation tests that demonstrate blocked lateral movement attempts. Add change records and periodic rule reviews to prove the program runs continuously, not as a one-time project.

Footnotes

1. HICP 2023 - 405(d) Health Industry Cybersecurity Practices