iso-27001-isms

# ISO 27001 ISMS Skill

ISO 27001 certifies a *system* (the ISMS), not a checklist — auditors check that you scoped it, assessed
risk, and can justify which Annex A controls you applied or excluded (the Statement of Applicability).
This skill builds that backbone: scope, risk treatment, and a defensible SoA, so certification is a
documented management system rather than a scramble.

## Required Inputs

Ask for these only if they aren't already provided:

- **ISMS scope** — the products, locations, and information assets in scope (and what's deliberately out).
- **Context & interested parties** — the business, its regulatory/customer security obligations, and key risks.
- **Risk approach** — how you identify, assess, and treat information-security risk (the SoA flows from the risk assessment, not the other way round).
- **Current controls** — what's already implemented across the Annex A domains.

## Output Format

### ISO 27001 ISMS: [organisation]

**1. Scope statement** — the boundary of the ISMS: assets, locations, exclusions and why.

**2. Context & risk** — interested parties and their requirements; the risk assessment method and risk acceptance criteria.

**3. Statement of Applicability (SoA)** — the heart of it: each Annex A control, applicable or not, status, and justification:

| Annex A control | Applicable? | Status | Justification |
|---|---|---|---|
| A.5 Access control policy | Yes | met | Required for customer data |
| A.8 Teleworking | No | n/a | No remote-access to in-scope systems — excluded with rationale |

(Excluding a control is fine — *excluding it without a justification* is an audit finding.)

**4. Risk treatment plan** — the top risks, the treatment (mitigate/accept/transfer/avoid), and the controls that address each.

**5. Implementation roadmap** — prioritised: mandatory clauses 4–10 (management system) first, then the highest-risk Annex A gaps, with owners and dates.

## Programmatic Helper

`scripts/soa_coverage.py` (stdlib only) scores SoA coverage and flags controls excluded without a
justification (the classic finding):

```bash
# soa.json: [{"control":"A.5.1","applicable":true,"status":"met|partial|gap","justification":"..."}, ...]
python3 scripts/soa_coverage.py soa.json
python3 scripts/soa_coverage.py soa.json --json
```

## Quality Checks

- [ ] The ISMS scope is explicit, including deliberate exclusions
- [ ] The SoA covers every Annex A control with an applicable/excluded decision
- [ ] Every excluded control carries a justification (the most common audit finding)
- [ ] The SoA traces to the risk assessment — controls exist to treat identified risks, not for show
- [ ] Mandatory management-system clauses (4–10) are addressed, not just the Annex A controls

## Anti-Patterns

- [ ] Do not exclude a control without a written justification — silent exclusions are audit findings
- [ ] Do not build the SoA before the risk assessment — applicability is *derived* from risk, not guessed
- [ ] Do not treat Annex A as the whole standard — clauses 4–10 (the management system) are mandatory and where many fail
- [ ] Do not mark controls "implemented" without evidence of operation — certification audits sample evidence
- [ ] Do not present this as certification — only an accredited body certifies; this prepares the ISMS

## Based On

ISO/IEC 27001 (ISMS clauses 4–10) and Annex A control set + the Statement of Applicability requirement.