The Term "Secure Enclave" Gets Thrown Around a Lot in CMMC Conversations
If you have been preparing for CMMC certification or sitting through vendor presentations, you have almost certainly heard the phrase "secure enclave." It sounds authoritative. It sounds expensive. And depending on who is using it, it can mean very different things. Before your organization invests significant time and money building or procuring one, it is worth understanding what the term actually means in the context of CMMC compliance, when it is genuinely necessary, and when simpler solutions will satisfy assessors just as well.
This post is written for compliance managers and executives at defense contractors who need a clear, practical answer — not a sales pitch.
What Is a Secure Enclave?
In the CMMC and federal contracting world, a secure enclave refers to a logically or physically isolated computing environment specifically designed to store, process, and transmit Controlled Unclassified Information (CUI) while meeting the security requirements of frameworks like NIST SP 800-171 and CMMC. The enclave separates CUI-handling systems from the rest of your corporate IT infrastructure, reducing the scope of your assessment and limiting exposure to untrusted systems and users.
The concept draws from classified information system design — where sensitive compartments are physically isolated — and applies similar principles to unclassified but sensitive defense information. In practice, a secure enclave for CMMC might be:
- A dedicated set of workstations, servers, and network segments for CUI work
- A cloud-based tenant built on a compliant platform such as Microsoft GCC High
- A hybrid architecture combining on-premises hardware with a government cloud environment
- A fully separate network with its own identity management, endpoint controls, and logging infrastructure
The defining characteristic is boundary control. A secure enclave only delivers compliance value when you have clearly documented what is inside it, what is outside it, and how information flows across that boundary. Without a well-defined CUI boundary, you do not have an enclave — you have an expensive network segment.
What CMMC Actually Requires
CMMC Level 2 — the tier applicable to most defense contractors handling CUI — requires implementation of all 110 security practices drawn from NIST SP 800-171. These practices span 14 domains including access control, audit and accountability, configuration management, incident response, and system and communications protection.
Nowhere in CMMC or NIST SP 800-171 does the word "enclave" appear as a mandatory architecture. What the framework requires is that you protect CUI wherever it lives. The enclave concept is a design strategy — often an effective one — for meeting those requirements, not a requirement in itself.
That said, a properly scoped and implemented enclave offers a significant practical advantage: it reduces the number of systems, users, and processes in scope for your assessment. A smaller, well-controlled environment is easier to document, easier to protect, and easier to defend in front of a C3PAO assessor. This is why many organizations pursuing CMMC, CUI, and DFARS compliance choose to build one.
Microsoft GCC High as a Cloud-Based Secure Enclave
For many small to mid-size defense contractors, the most practical path to a compliant enclave is not on-premises hardware — it is Microsoft GCC High. GCC High is a purpose-built government cloud environment that meets the requirements of FedRAMP High, ITAR, DFARS 252.204-7012, and CMMC. Data stored and processed in GCC High is physically located in the United States and accessible only by screened U.S. citizens working for Microsoft.
When properly configured, a GCC High tenant can serve as your CUI enclave. Your employees access CUI through Microsoft 365 GCC High applications — Teams, SharePoint, Exchange, OneDrive — while your commercial or personal devices and accounts remain outside the enclave boundary. Key configuration elements that make this work include:
- Conditional access policies that enforce compliant device requirements
- Microsoft Purview sensitivity labels applied to CUI documents and emails
- Multi-factor authentication enforced across all enclave users
- Microsoft Defender for Endpoint deployed on all in-scope devices
- Audit logging and SIEM integration to support incident response and continuous monitoring
- External sharing disabled or tightly restricted to other approved government tenants
The critical point: licensing GCC High is not the same as having a compliant enclave. The platform provides the capability; your configuration and documented controls determine whether it meets assessment standards. Organizations that migrate to GCC High without a structured configuration program routinely fail their gap assessments on controls that the platform technically supports but was never set up to enforce.
On-Premises Enclaves: When They Make Sense
Cloud-based enclaves are not the right answer for every organization. Certain defense contractors — particularly those in aerospace and defense manufacturing — handle CUI that is tightly integrated with operational technology, engineering workstations, or classified program environments. In those cases, an on-premises or hybrid enclave may be the more appropriate architecture.
An on-premises enclave typically includes:
- A physically or logically separated network segment with controlled ingress and egress points
- Dedicated workstations that are not dual-homed to the corporate network
- Separate identity and access management, often using Active Directory isolated from the corporate domain
- Hardware-based multi-factor authentication for privileged access
- Endpoint detection and response tools deployed on all in-scope assets
- A System Security Plan (SSP) that accurately describes the environment and maps controls to NIST SP 800-171 practices
On-premises enclaves require significantly more ongoing maintenance than cloud-based solutions, and they carry higher risk of configuration drift over time. They also require dedicated IT resources — or a managed security services provider — to maintain patch currency, monitor for threats, and respond to incidents. For smaller organizations without that internal capacity, a well-configured GCC High environment is almost always a more sustainable compliance posture.
Do You Actually Need a Secure Enclave?
The honest answer depends on two things: what CUI you handle and how your current IT environment is structured.
If your entire workforce handles CUI as part of daily operations and your IT infrastructure was already built around security best practices, you may be able to apply NIST SP 800-171 controls broadly without constructing a formal enclave. In this scenario, your entire environment essentially becomes the enclave — which works, but creates a larger assessment scope and more controls to demonstrate.
If only a subset of your employees handle CUI — common in organizations that also perform commercial work or have a blended workforce — building a defined enclave to limit scope is almost always the smarter strategy. Assessors can only evaluate what is in scope. A smaller, tightly controlled environment reduces both your compliance cost and your ongoing operational burden.
Before making an architectural decision, you need a clear CUI boundary assessment. Organizations that skip this step and build an enclave based on assumptions frequently discover mid-project that CUI is flowing through systems they never intended to include — invalidating the scope they built the enclave around. Our Federal and SLED Risk Assessment service is specifically designed to surface these boundary issues before they become assessment findings.
Common Mistakes When Building a CMMC Enclave
After working with dozens of defense contractors on enclave design and implementation, the same patterns of error appear repeatedly:
- Scope creep during implementation: CUI ends up in systems outside the intended boundary — shared drives, personal email, unmanaged mobile devices — because no one communicated the handling requirements clearly to staff.
- Treating the enclave as a one-time project: Enclaves require continuous monitoring, patch management, and periodic reassessment. A compliant environment on day one can fall out of compliance within months without governance processes in place.
- Inadequate SSP documentation: Assessors need to see a System Security Plan that accurately describes the enclave, not a template that was never tailored to the actual environment. This is one of the most common reasons organizations fail their initial assessments.
- Assuming cloud migration equals compliance: As noted above, moving to GCC High or Azure Government satisfies your cloud platform requirement. It does not configure your controls for you.
- Ignoring the supply chain: Subcontractors and vendors who access CUI within your environment extend your enclave boundary. Their access must be governed, monitored, and documented.
These are exactly the issues that a Regulatory vCISO engagement is designed to catch and correct before they surface in an assessment.
Building Your Enclave Strategy
A secure enclave for CMMC is not a product you can purchase off the shelf. It is an architecture you design, implement, document, and maintain. Whether you choose a cloud-based solution on GCC High, an on-premises environment, or a hybrid of both, the fundamentals remain the same: define your CUI boundary, implement the 110 controls, document everything, and build operational processes that keep the enclave compliant over time.
For most defense contractors, the right starting point is a gap assessment that maps your current environment against NIST SP 800-171 requirements and identifies where your CUI actually lives today. From there, enclave architecture decisions can be grounded in evidence rather than assumption — and your compliance investment can be targeted where it will actually move your SPRS score and assessment readiness forward.
If you want to understand what this looks like for your specific situation, the CMMC 2.0 for DoD and Federal Contractors resource is a practical starting point for your team. And when you are ready to engage a compliance partner who has built these environments for defense contractors across the industrial base, request a quote from Cleared Systems and we will help you scope the right approach for your organization.