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NIST SP 800‑171 Requirements
If you handle Controlled Unclassified Information (CUI) for the Department of Defense or a prime contractor, NIST SP 800‑171 is not optional. It is the baseline for protecting CUI in nonfederal systems, and it is the technical foundation for CMMC Level 2.
Neutral Partners helps you define your CUI boundary, assess your current state, calculate and document your score, and remediate gaps with evidence that stands up to reviews. The goal is practical: protect CUI, meet DFARS obligations, and stay eligible for contracts.
At a Glance
- Best for: defense contractors, subcontractors, and suppliers that store, process, or transmit CUI
- Driven by: DFARS clauses (including 252.204‑7012) and DoD assessment expectations
- Core deliverables: System Security Plan (SSP), Plan of Action and Milestones (POA&M), evidence library, and remediation roadmap
- Common failure point: unclear CUI scope that makes compliance expensive and hard to prove
Start with a CUI scope and a real gap assessment.
Book a Discovery SessionWhat Is NIST SP 800‑171
NIST SP 800‑171 defines security requirements for protecting Controlled Unclassified Information in nonfederal systems and organizations. It is written so federal agencies can flow requirements into contracts and suppliers can implement a consistent control baseline.
The standard is organized into requirement families such as access control, incident response, audit logging, configuration management, and system integrity. In practice, NIST 800‑171 requires you to do three things well:
- control the boundary: know where CUI lives and limit systems in scope
- implement controls: technical and operational safeguards that protect CUI
- prove it: documentation and evidence that shows controls operate consistently
How NIST 800‑171 Connects to DFARS and CMMC
NIST 800‑171 shows up in defense contracting through DFARS clauses and DoD assessment expectations.
- DFARS 252.204‑7012: requires safeguarding covered defense information and cyber incident reporting. It also includes expectations around using cloud providers that meet FedRAMP Moderate equivalent requirements when applicable.
- DoD assessments and SPRS: many contractors must conduct a Basic self‑assessment and post a summary score in the Supplier Performance Risk System (SPRS).
- CMMC Level 2: aligns to NIST 800‑171 requirements. CMMC changes the enforcement mechanism by requiring third‑party assessments in many cases.
The practical takeaway: NIST 800‑171 is the control baseline. Your contract and customer requirements determine how you must validate and report.
Who Needs NIST 800‑171
If you are part of the Defense Industrial Base and any part of your performance touches CUI, you should assume NIST 800‑171 applies.
Common candidates include:
- Prime contractors and subcontractors: engineering, manufacturing, logistics, and program support
- Software and SaaS vendors: tools used in defense programs that touch CUI or defense information
- Professional services firms: design, testing, and research organizations handling sensitive program data
- Managed service providers: MSPs supporting defense contractors where CUI exists in client environments
- Supply chain partners: organizations exchanging drawings, specifications, or controlled technical data
What NIST 800‑171 Covers
NIST 800‑171 requirements cover both technical controls and operational discipline. Buyers and assessors care about evidence that shows controls operate.
Common requirement areas include:
- Access control: least privilege, MFA, session controls, and remote access restrictions
- Audit and accountability: log generation, retention, review, and investigation support
- Configuration management: baselines, change control, and secure settings management
- Identification and authentication: credential management and strong authentication practices
- Incident response: documented procedures, reporting, and tested response capability
- Media protection: handling and disposal for systems and removable media that touch CUI
- Personnel security: onboarding, offboarding, and role based access controls
- Risk assessment: vulnerability management, remediation, and risk treatment decisions
- System and communications protection: encryption and network safeguards
- System integrity: malware protection, monitoring, and flaw remediation routines
Evidence Assessors Expect
Whether you are preparing for a DoD review, a customer review, or CMMC Level 2, the evidence expectations are similar.
Expect to produce:
- Scope artifacts: CUI data flow diagrams, system boundary definition, asset inventory, and network diagrams
- Program artifacts: policies, procedures, and defined control owners
- SSP: a System Security Plan that describes how each requirement is implemented
- POA&M: a Plan of Action and Milestones that tracks gaps with owners and target dates
- Operational artifacts: access reviews, change tickets, patch reports, vulnerability scan results, incident tickets, training records
- Technical artifacts: configuration exports, screenshots, logging dashboards, encryption settings, MFA enforcement proof
- Supplier artifacts: vendor inventory, MSP responsibilities, cloud shared responsibility statements
The SSP and evidence must match reality. If an SSP says “we review logs weekly,” you need dated records showing the weekly review actually happened.
NIST 800‑171 Roadmap
Teams get stuck when they treat NIST 800‑171 as a policy project. It is an engineering and operations project with documentation as proof.
Define the CUI boundary
- identify CUI types and where they enter your organization
- map CUI flows across systems, users, and third‑party services
- reduce scope by isolating CUI to specific enclaves when possible
Run a gap assessment and score your current state
- assess implementation against each requirement using NIST 800‑171A style assessment procedures
- calculate your score using the DoD assessment methodology when applicable
- document gaps and evidence weaknesses
Build the SSP and POA&M
- write the SSP so it describes real control implementation
- build a POA&M that is realistic and owned, not aspirational
- ensure the SSP references evidence locations
Remediate gaps and operationalize control routines
This is where most work lives.
- implement MFA and tighten privileged access
- harden configurations and enforce baselines
- improve logging coverage and review routines
- implement patch and vulnerability management with proof
- strengthen incident response and reporting readiness
Prepare for validation and reviews
- test controls and evidence like an assessor would
- correct weak narratives, missing artifacts, and drifted configurations
- confirm vendor and MSP responsibilities are documented and enforced
Sustain compliance
NIST 800‑171 work does not stay done unless you build recurring routines.
- schedule access reviews, log reviews, and patch cycles
- keep the SSP current as systems change
- update the POA&M as remediation completes
- track suppliers and cloud changes
If you cannot explain your CUI boundary, you cannot prove compliance.
We will map your boundary, run a real assessment, and build the roadmap to close gaps with evidence.
Schedule a Discovery SessionCommon NIST 800‑171 Gaps
- Scope sprawl: CUI is scattered across endpoints, shared drives, and SaaS tools
- Weak MFA and privileged access: MFA is partial, privileged accounts are unmanaged, and reviews are inconsistent
- Logging without review: logs exist, but routine review and response evidence is missing
- Patch discipline gaps: scans run, but remediation and exceptions are not provable
- SSP mismatch: the SSP describes an ideal state, not the real implementation
- Vendor and MSP ambiguity: responsibilities are assumed instead of documented and verified
- POA&M abuse: too many open items with no owners, no dates, and no closure evidence
How Neutral Partners Helps
We help defense contractors build provable compliance without wasting time on the wrong scope.
What we deliver
- CUI scope and enclave design: boundary definition, data flows, and scope reduction strategies
- Gap assessment: requirement by requirement assessment with evidence review
- SSP and POA&M development: documentation that matches reality and supports validation
- Remediation support: technical and operational control implementation and evidence collection
- Readiness testing: assessor style testing to reduce surprises
- Ongoing program support: cadence for evidence, reviews, and SSP maintenance
Proof matters. Since 2017, we have maintained a 100% audit success rate across more than 700 successful audits and assessments. We keep that record by focusing on evidence and operational execution, not wishful documentation.
NIST 800‑171 FAQs
Is NIST 800‑171 the same as CMMC?
No. NIST 800‑171 defines the security requirements. CMMC defines how those requirements are validated and enforced for defense contractors. Many CMMC Level 2 requirements align directly to NIST 800‑171.
What is an SSP and why does it matter?
The SSP explains how you implement each requirement within the CUI boundary. Assessors and customers use it to understand your approach and to validate evidence. A vague SSP creates follow‑up questions and delays.
Can we keep gaps in a POA&M?
That depends on the validation method and the requirement. A POA&M is a remediation tracking tool, not a substitute for implementation. In practice, you should treat open POA&Ms as risk and close them aggressively.
What is the biggest mistake teams make with SPRS scoring?
They score based on intent rather than evidence. Scores should reflect implemented controls within the defined boundary, supported by artifacts that prove operation.
Does using Microsoft 365 make NIST 800‑171 easier?
It can, but only when configured correctly and when responsibilities are clear. Default settings do not equal compliance. You still need to configure, monitor, and evidence controls.
Key Resources
- NIST SP 800‑171 Rev. 3
- NIST SP 800‑171A Rev. 3 assessment procedures
- DoD NIST 800‑171 assessment methodology
- DFARS 252.204‑7012 clause text
- SPRS reference materials
Useful Resources
- [Internal] CUI boundary mapping template
- [Internal] SSP template and evidence map
- [Internal] NIST 800‑171 readiness checklist
Make NIST 800‑171 a Growth Lever
Defense customers want proof you protect CUI. When scope is clear and evidence is disciplined, reviews move faster and your team spends less time answering the same questions.
Start with a short working session. We will map your CUI boundary, your top gaps, and the next three moves.