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

Risk is not static. Define a refresh cadence and the triggers that force re-assessment (new system, major architecture change, significant incident, new threat intel). Track risk-acceptance decisions and treatment progress over time.

5. Drive treatment decisions

Hand the ranked register to risk owners. For each risk choose a treatment — mitigate (add/strengthen controls), transfer (insurance, contractual), avoid (stop the activity), or accept (document residual risk with an authorizing signature). Re-score residual risk after planned controls to show the post-treatment position.

Key Concepts

Concept	Definition
Threat source	The cause of a threat event: adversarial, accidental, structural, or environmental.
Threat event	A specific action or occurrence that could cause harm (mapped to ATT&CK for adversarial cases).
Vulnerability	A weakness that a threat event can exploit.
Predisposing condition	A condition that increases or decreases the likelihood of adverse impact (e.g., internet exposure).
Likelihood	The chance a threat event initiates/occurs and results in adverse impact.
Impact	The magnitude of harm if the event succeeds.
Risk	A function of likelihood and impact; the expected harm to the organization.
Inherent vs residual risk	Risk before vs after planned/implemented controls.
Risk tolerance / appetite	The level of risk leadership is willing to accept.
Risk register	The prioritized record of risks, scores, owners, and treatments.

Tools & Systems

• NIST SP 800-30 Rev 1 — the methodology and Appendices D–I taxonomies (threat sources, events, vulnerabilities, likelihood, impact, risk).
• NIST SP 800-39 — enterprise risk-management context (three tiers).
• MITRE ATT&CK — to enumerate and ground adversarial threat events in observed TTPs.
• Vulnerability scanners / pen-test reports — empirical vulnerability input.
• Threat intel sources — sector ISACs, vendor feeds, internal incident history for likelihood grounding.
• GRC / risk-register tooling — spreadsheet, or platforms such as ServiceNow GRC, Archer, OneTrust, to store and track the register.
• FAIR (optional) — a quantitative model if leadership wants risk expressed in dollar ranges rather than qualitative bands.

Common Scenarios

• CSF/ISO/SOC 2 needs a risk analysis. Run 800-30 to produce the documented assessment those frameworks require as input, then map results to their control sets.
• New system before go-live. Assess threat events against the system's architecture and feed the result into the authorization (RMF Select/Authorize) decision.
• Board wants the top risks. Deliver a ranked register with impacts in business terms and clear treatment recommendations.
• Post-incident. Re-assess the affected systems; the incident updates likelihood evidence and may surface new threat events.
• Annual refresh. Re-score against current threat intel and control changes; show movement in residual risk year over year.

Output Format

Produce a Risk Assessment Report using assets/template.md, containing:

1. Purpose, scope, and tier — what was assessed and why.
2. Assumptions, constraints, and risk model — the factors and scales used (so results are reproducible).
3. Threat sources — by type, with adversarial characterization.
4. Threat events — each with affected assets and ATT&CK mapping where adversarial.
5. Vulnerabilities and predisposing conditions — tied to threat events.
6. Risk register — table: ID, threat event, asset, likelihood, impact, risk level, contributing vulnerabilities, recommended treatment, owner, residual risk.
7. Top risks summary — ranked, in business terms, for leadership.
8. Maintenance plan — refresh cadence and re-assessment triggers.

Use scripts/process.py to score the register from a risk-input JSON (likelihood × impact → risk level on a configurable matrix), rank risks, and emit the register table.