NIST RMF and ISO 27001 solve the same underlying problem — proving your security controls actually match your risk — with different vocabularies. If you are heading toward an Authority to Operate (ATO) or an ISO 27001 certification, mapping the two frameworks together saves you from doing the work twice.
The 7-Step Risk Management Framework
NIST RMF (SP 800-37 Rev 2) runs in seven steps: Prepare, Categorize, Select, Implement, Assess, Authorize, and Monitor. Most teams under-invest in “Prepare” — defining risk tolerance and organizational context up front — and pay for it later when every subsequent step has to be redone against a moving target.
- Prepare — establish context, roles, and risk tolerance
- Categorize — classify the system based on impact (FIPS 199)
- Select — choose a baseline control set (NIST SP 800-53)
- Implement — deploy and document the controls
- Assess — independently test whether controls work as intended
- Authorize — a senior official formally accepts the residual risk
- Monitor — continuously track control effectiveness and risk changes
Mapping RMF to ISO 27001 Annex A
ISO 27001’s Annex A controls map closely to NIST SP 800-53 control families — access control, cryptography, physical security, incident management — which means a system already assessed against 800-53 is most of the way to an ISO 27001 Statement of Applicability. The gap is usually the ISO-specific management system requirements: a documented ISMS, management review, and internal audit cadence.
Running the Gap Analysis
Before you touch a single control, inventory what you already have against your target baseline and score each control as met, partially met, or not met. That gap list becomes your project plan — and your evidence, when the auditor or authorizing official asks how you prioritized the work.
Building a POA&M That Survives an Audit
A Plan of Action and Milestones documents every control gap, the remediation plan, the resources required, and a completion date — and it is often the difference between an ATO with conditions and no ATO at all. Keep it current; a stale POA&M is a bigger red flag to an assessor than an honest list of open gaps.
Get the Free NIST RMF & ISO 27001 Implementation Template
Our template includes a 7-step RMF tracker, an Annex A control mapping worksheet, a gap analysis matrix, and a POA&M starter — free to download.
Small Business Path to Compliance
You do not need a compliance department to start this. See how we help small businesses run a right-sized NIST RMF or ISO 27001 gap analysis without hiring a full-time compliance team.