Summary: For organizations pursuing CMMC, the requirements can quickly get overwhelming. While the process is designed to strengthen security practices, NIST SP 800-171 controls can be tricky to manage and frequently cause delays for OSCs. Let’s look at five controls individually.
For organizations working toward Cybersecurity Maturity Model Certification (CMMC) Level 2, aligning with NIST SP 800-171 can be more demanding than expected. While the framework is built to safeguard Controlled Unclassified Information (CUI) across the Defense Industrial Base (DIB), some requirements demand a level of consistency, documentation, and operational maturity that many OSCs are still developing. While most OSCs can handle the foundational controls, we’ve seen five NIST 800-171 controls that consistently slow progress and create friction during assessments.
1. Multi-Factor Authentication (3.5.3)
Multi-factor authentication (MFA) may sound straightforward on paper, but the reality for many OSCs is that it’s one of the most frustrating NIST SP 800-171 requirements to implement. The challenge isn’t whether MFA is important, it’s about making it work across aging systems, hybrid environments, and user groups who aren’t always thrilled about having extra steps during login.
Some of the most common pitfalls of MFA implementation include:
- Lack of MFA support: Older or niche systems don’t always support modern MFA methods.
- Added layer of configuration and oversight: Enforcing MFA consistently, especially for privileged and remote access, requires more configuration and oversight for teams.
- User resistance: Users push back when MFA slows them down or introduces friction, creating adoption hurdles.
C3PAO Tip for OSCs: Start with the most sensitive accounts.
These accounts include administrators, remote users, and users with elevated access. Once those bases are covered, expand MFA in phases. Short but targeted user training, such as quick walkthroughs, can dramatically reduce the resistance and confusion that usually stall MFA rollouts.
2. Incident Response Planning (3.6.1-3.6.3)
Establishing, maintaining, and testing an incident response (IR) capability is one of the more demanding parts of NIST 800‑171, especially for small and mid‑sized OSCs. The requirement goes far beyond having a documented plan. Organizations must ensure the process is actionable, repeatable, and regularly exercised.
Limited staffing, competing priorities, and a lack of specialized knowledge often make it difficult for organizations to keep IR programs current and conduct routine testing (e.g., tabletop exercises).
C3PAO Tip for OSCs: If your internal bandwidth is tight, consider partnering with a managed security service provider (MSSP) or a qualified consultant.
An MSSP or consultant can help design, refine, and test your IR plan. A concise, realistic, and tested process is far more effective and defensible during an assessment.
3. System Security Plan (SSP) and Plan of Action & Milestones (POA&M) (3.12.4)
Many OSCs discover that documentation can be one of the biggest hurdles in meeting NIST 800‑171 requirements. The SSP must clearly explain how each control is implemented, while the POA&M must outline accurate and realistic remediation steps for any controls not yet implemented. Both documents need to be detailed, current, and accurate to how your environment operates. When either one falls behind or becomes generic, gaps show up quickly during assessments.
It’s important to remember that:
- SSPs require clear and accurate descriptions of control implementation, not copied text or generic templates.
- POA&Ms must include real timelines, owners, and workable corrective actions.
- Documentation must reflect the current environment, not last quarter’s version.
- Assessors rely heavily on the SSP and POA&M to judge maturity, making outdated or vague content a major liability.
C3PAO Tip for OSCs: Utilize the right tools and update documentation routinely.
Use structured templates or compliance automation tools built specifically for NIST 800-171. Moreover, update your SSP and POA&M routinely, not just before an audit. Having these documents up to date eliminates last-minute scrambles for your team, and gives assessors a clear picture of your security posture.
4. Audit Logging and Monitoring (3.3.1-3.3.7)
Most OSCs underestimate audit logging and monitoring until they begin mapping out what NIST 800-171 expects. Many OSCs quickly discover that keeping logs, protecting their integrity, and reviewing them is far more work than anticipated, especially without a security information and event management (SIEM) solution or dedicated security staff. The volume of logs alone can overwhelm small teams, and manual review often falls to the bottom of the priority list.
Recurring challenges often occur because of these common scenarios:
- Many OSCs lack centralized logging tools, making it difficult to collect and review logs across systems.
- Daily or even weekly log reviews require dedicated time and specialized knowledge that many teams simply don’t have.
- Ensuring logs are protected from tampering, stored appropriately, and retained for required periods all contribute to additional operational overhead.
C3PAO Tip for OSCs: Centralize logs from your highest risk systems.
Centralize logs from your highest risk systems, such as domain controllers, critical servers, and authentication sources. Cloud native monitoring tools or managed detection and response (MDR) services can shoulder much of the day-to-day burden and ensure consistent review. This approach provides better visibility with far less strain on your internal resources.
5. Media Protection (3.8.9-3.8.11)
Many OSCs don’t rely heavily on removable media anymore, which often leads to them overlooking those controls entirely. However, when portable storage is used, even for legitimate operational reasons, the lack of consistent encryption, tracking, and sanitization practices becomes a compliance risk. Assessors pay close attention to this category because it directly affects how CUI can be copied, transported, and disposed of.
Some of the most common reasons OSCs run into trouble with media protection include:
- Encryption for removable media is not enforced across all devices or user groups.
- Chain of custody procedures for handling CUI on portable media are rarely documented.
- Sanitization steps vary from person to person, with no formal method ensuring data is wiped correctly.
- Teams assume that they “don’t use USBs much anyway” which leads to gaps assessors can immediately call out.
C3PAO Tip for OSCs: Adopt a “minimize when possible” approach to removable media.
If portable storage cannot be eliminated, enforce full disk encryption, document a chain of custody process, and establish a clear sanitization method that everyone follows. Even a simple written procedure can go a long way toward closing this often-missed gap.
Final thoughts
The hardest part of NIST 800-171 compliance is keeping people, processes, and documentation moving in the same direction. For many OSCs, the weight of day-to-day operations makes it easy for these requirements to slip. CMMC compliance can feel demanding at times, but it’s also manageable when you take it one step at a time.
With the right combination of clear processes, practical tools, and a team that understands the “why” behind the work, organizations can steadily build the maturity needed to navigate NIST SP 800-171 controls with confidence. The path isn’t always smooth, but it is achievable, and each improvement strengthens your long-term readiness in the defense contracting space.
You don’t have to tackle CMMC alone. As an authorized CMMC C3PAO, our team can provide the support you need to move forward with confidence, no matter where you are on your journey. Set up a complimentary consultation with Aprio’s CMMC professionals today.
