Conducting a Cyber Risk Assessment with NIST SP 800-30

When to Use

• When the organization needs a real risk assessment — an analysis of specific threats, likelihoods, and impacts — rather than a maturity score against a framework. (Maturity tells you how mature your practices are; a risk assessment tells you what could hurt you and how badly.)
• When another framework requires a documented risk analysis as a mandatory input: NIST CSF (ID.RA), ISO 27001 (Clause 6.1.2), NIST RMF / 800-37 (the Prepare and Select steps), SOC 2 (CC3), PCI DSS, or HIPAA (§164.308(a)(1)(ii)(A)).
• When standing up or significantly changing a system and you must understand its risk before authorization or go-live.
• When leadership asks for the organization's top risks, ranked, with a rationale they can defend to a board or regulator.
• When building or refreshing an enterprise risk register.

Prerequisites

• An inventory of in-scope assets, systems, and the information types they handle (system boundary defined).
• Access to threat intelligence (internal incident history, sector ISAC feeds, MITRE ATT&CK) to ground threat-event likelihood in observed behavior.
• Vulnerability data (scan results, pen-test findings, configuration/architecture review) for the in-scope systems.
• Business context: which missions/processes the systems support, and what impact to confidentiality, integrity, or availability would mean in business terms.
• Agreement on the risk model and scales before scoring, so results are comparable and repeatable (see references/standards.md).
• Familiarity with the three-tier risk-management context from NIST SP 800-39 (organization, mission/business process, information system).

Workflow

NIST SP 800-30 Rev 1 defines four steps. Steps 1 and 4 bookend the assessment; Step 2 is the analytic core.

1. Prepare for the assessment

Define and document:

• Purpose (e.g., support an authorization decision, inform control selection, satisfy ISO 6.1.2).
• Scope — organizational tier (Tier 1/2/3), systems, and time horizon.
• Assumptions and constraints (e.g., assume an external adversarial threat with moderate capability).
• Information sources — threat, vulnerability, and impact inputs.
• Risk model and analytic approach — the factors (threat source, threat event, vulnerability, likelihood, impact) and the scales (qualitative Very Low–Very High, or semi-quantitative 0–10). Lock these now.

2. Conduct the assessment

Work through the analytic tasks in order. The 800-30 appendices provide the reference taxonomies (D–I).

2a. Identify threat sources (Appendix D). Classify by type: Adversarial (individuals, groups, nation-states — characterize capability, intent, targeting), Accidental (user error), Structural (equipment/software failure), Environmental (natural disasters, infrastructure outages).

2b. Identify threat events (Appendix E). The specific actions a source could take (e.g., "adversary exfiltrates credentials via phishing then moves laterally"). Map adversarial events to MITRE ATT&CK techniques for traceability.

2c. Identify vulnerabilities and predisposing conditions (Appendix F). Weaknesses (missing MFA, unpatched service) and conditions that make exploitation more or less likely (internet exposure, flat network, lack of segmentation).

2d. Determine likelihood (Appendix G). Assess the likelihood that a threat event is initiated (adversarial) or occurs (non-adversarial), and the likelihood it results in adverse impact given the vulnerabilities. Combine into an overall likelihood on the agreed scale.

2e. Determine impact (Appendix H). Magnitude of harm if the event succeeds — to operations, assets, individuals, other organizations, or the nation. Express against the agreed scale and in business terms.

2f. Determine risk (Appendix I). Risk is a function of likelihood and impact. Plot each threat event on the risk matrix (e.g., likelihood × impact → Very Low … Very High). Record the risk level, the contributing factors, and uncertainty/assumptions.

3. Communicate and share results

Produce the risk register and an executive briefing. For each risk: the threat event, affected assets, likelihood, impact, risk level, key contributing vulnerabilities, and a recommended treatment. Rank by risk level so decision-makers see the top risks first.

4. Maintain the assessment

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