CMMC Enclave: Hybrid vs. Cloud-Only Models Explained
When protecting Controlled Unclassified Information (CUI), the first and biggest decision is defining your security boundary, or “enclave.” Choose too broad a scope and you’ll drown in complexity and cost. A CUI enclave can provide an affordable solution for small businesses seeking Cybersecurity Maturity Model Certification or CMMC compliance.
Choose too narrow or the wrong model and you’ll miss data flows or struggle to support legacy systems. In this article, we compare two main enclave approaches: Hybrid Boundary and Cloud-Only Enclave. This will help you choose the best model for your small business and keep CUI safe.
Why CMMC Scoping Matters
What is “scope”? Your enclave scope is the set of systems, users, and data stores that must meet CMMC controls. It dictates:
- Which servers and applications you must secure and document.
- Which employees need specialized training and access restrictions.
- How much time and money you’ll spend on licenses, audits, and ongoing maintenance.
Get your scope right, and you streamline compliance—no wasted effort or unnecessary tools. Get it wrong, and you end up overspending or failing audits.
1. Hybrid Boundary Model
Definition: You keep your existing on-premise servers and workstations in place, but all CUI data is routed into a FedRAMP-certified cloud enclave via secure Zero-Trust Network Access (ZTNA) tunnels.
How it works:
- On-premise systems continue to run legacy apps.
- A lightweight ZTNA gateway inspects and forwards CUI flows to the cloud enclave.
- Non-CUI traffic remains on your regular network.
Pros:
- Leverages existing infrastructure without wholesale rehosting.
- Minimal disruption for legacy applications that can’t easily move.
- Phased adoption lets you pilot in the cloud while keeping key systems on-prem.
Cons:
- Dual licensing costs for both on-prem security tools and FedRAMP cloud services.
- Complex network setup and ongoing tunnel maintenance.
- Longer rollout—you’re managing two environments at once.
2. Cloud-Only Enclave Model
Definition: All CUI—and only CUI—lives in a single FedRAMP-certified cloud environment. Your day-to-day network remains untouched for non-sensitive workloads.
How it works:
- Migrate CUI data and applications into the cloud enclave.
- Use secure web or VPN access for users who handle CUI.
- Keep corporate email, file shares, and non-CUI services outside the enclave.
Pros:
- Simplest boundary: one environment to secure, monitor, and audit.
- Lower administrative overhead: no on-prem security tools to license or patch.
- Predictable costs: per-enclave pricing vs. per-seat or per-server licenses.
Cons:
- Migration effort: Some legacy apps may need refactoring or replacement.
- Data transfer planning: You’ll need a secure, one-time bulk ingest or sync process.
3. Comparing Cost & Complexity
In a typical small business, using only cloud services can cut costs by 20% compared to a hybrid setup. This is particularly true when considering the costs of dual tool licenses and maintenance.
4. Decision Checklist
Answer these four questions to see which model fits you best:
1. Must-stay: legacy? Do critical applications exist that cannot be rehosted in the cloud?
2. Budget split: Do you have more budget for one-time migration or ongoing dual-environment licenses?
3. Timeline urgency: How quickly must you be audit-ready—within months, or do you have a year?
4. Administrative capacity: Can your team support two environments, or do you need a simpler single-pane solution?
Score each on a 1 (low) to 5 (high) scale, then total your points: higher overall scores favor cloud-only.
5. Diagramming Your Enclave Boundary
A clear flow diagram is worth a thousand words to your assessor. Follow these steps:
1. Map data paths: Show where CUI is created, stored, and transmitted.
2. Label assets: Identify servers, cloud buckets, and user groups involved.
3. Draw the boundary: Encircle only CUI systems in your enclave.
4. Indicate controls: Note where MFA, encryption, and monitoring apply.
6. Migration & Implementation Tips
• Start small: Pilot your enclave with a non‐critical CUI dataset.
• Mock assessment: Run an internal audit at each phase to catch gaps early.
• Rollback plan: Keep your original on‐prem systems on standby during cutover.
• Communication: Inform users of new access processes and provide quick reference guides.
7. Ongoing Maintenance & Monitoring
Regardless of the model, maintaining compliance requires:
• Continuous monitoring: Monitor for suspicious activity in real-time.
• Regular patching: Apply updates to enclave systems within 30 days.
• Quarterly reviews: Update your policies, diagrams, and evidence.
• Annual drills: Conduct mini-assessments to keep your team audit-ready.
Wrap-Up & Next Steps
Choosing between hybrid and cloud-only enclaves is the foundation of your CMMC journey. Use the decision checklist and boundary diagrams to pick the model that matches your legacy constraints, budget, and timeline. With the right scope in place, your path to compliance becomes clear and cost‐effective.
Ready to see how CORE Vault’s fully managed cloud enclave can simplify your CUI scope? Get a Free Demo. Call us at 866-354-0300 as ask for a CORE Vault demo.
