The SSP is a foundational element of your cybersecurity posture and one of the first things your Certified Third-Party Assessment Organization (C3PAO) will review. A well-developed SSP doesn’t just tell assessors what you intend to do; it explains what you’ve already done, how you’ve implemented the required controls, and where any gaps remain.

Here’s what you need to know to build an SSP that’s audit ready and tailored to your environment.

What Is a System Security Plan?

A SSP is a living document that outlines how your organization meets the security requirements in NIST SP 800-171, which is a foundation of CMMC Level 2. It should describe:

• The systems and environments where Controlled Unclassified Information (CUI) is stored, processed, or transmitted.
• The security controls you’ve implemented.
• The boundaries, roles, responsibilities, and technologies used to protect those systems.

In other words, it answers the question: How are you protecting CUI today and what’s your plan to address any gaps?

Why a Strong SSP Matters for CMMC

CMMC 2.0 requires that contractors handling CUI at Level 2 either self-assess or undergo a third-party certification. In both cases, a complete and detailed SSP is required. Assessors won’t accept a generic template or a one-paragraph overview. They need specifics. If your SSP is incomplete, outdated, or inaccurate, it could delay or derail your path to certification.

Key Elements of an Effective SSP

To meet CMMC expectations, your SSP should include the following:

1. System Identification

• Name and description of the system
• Description of how it processes or stores CUI
• System boundaries and components

2. Roles and Responsibilities

• Who is responsible for implementing and maintaining security controls?
• What are their roles in incident response, access control, system monitoring, etc.?

3. Control Implementation

For each of the 110 NIST SP 800-171 controls, explain:

• How the control is implemented.
• What technologies or procedures support it.
• The role(s) of personnel who operate and maintain the technologies and implement the procedures. During the assessment, the personnel should be able to provide the evidence that supports your implementation (e.g., logs, screenshots, configurations).

4. Interconnected Systems

• Describe how your system interacts with external networks, cloud providers, or vendors.
• Explain how you manage risk across these boundaries.

5. Plan of Action & Milestones (POA&M)

• If some controls aren’t yet met, the POA&M should outline how and when they will be addressed. This is only acceptable for specific controls. 
• Include ownership and deadlines for each corrective action.

Common SSP Pitfalls to Avoid

Remember: A strong SSP shows that your organization understands and takes ownership of its cybersecurity obligations. Here are some common mistakes: 

• Copy-paste templates with no connection to your actual environment
• Vague descriptions of control implementations
• Missing links to evidence or lack of traceability
• Outdated information or personnel who no longer work at the organization
• No linkage between the SSP and your POA&M
• Failing to address all control requirements

Need Help? Start With a Readiness Review

At IBSS, we help defense contractors move from generic templates to real-world documentation that holds up under CMMC scrutiny. Whether you’re writing your SSP from scratch or fine-tuning a draft, we’ll work with your team to:

• Translate technical controls into plain-language documentation.
• Align your security practices with NIST SP 800-171 requirements.
• Prepare supporting evidence and documentation for assessment readiness.
• Integrate your SSP with your broader compliance strategy.

Book your CMMC Readiness Call today or send us an email at CMMCC3PAO@ibsscorp.com to start the path toward certification with a team that knows the process inside and out.

About IBSS

Since 1992, IBSS has provided transformational consulting services to the Federal defense, civilian, and commercial sectors. Our services include cybersecurity and enterprise information technology, environmental science and engineering (including oceans, coasts, climate, weather, and satellite), and professional management services.

Our approach is to serve our employees by investing in their growth and development. As a result, our employees bring greater capabilities and provide an exceptional level of service to our clients. In addition to creating career development opportunities for our employees, IBSS is passionate about giving back to the community. We strive to leave something better behind for the next generation. 

We measure our success by the positive impact we have on our employees, clients, partners, and the communities we serve. Our tagline, Powered by Excellence, is a recognition of the employees that make up IBSS and ensures we deliver results with quality, applying industry best practices and certifications. Read more About Us.

Keywords: CMMC, C3PAO, DoD Requirements, NIST SP 800-171, Cybersecurity