| Scope and covered activity | ISO/IEC 27005 is guidance for information security risk management that supports ISO/IEC 27001 and risk-based control decisions. | FAIR is a quantitative information-risk analysis model used to estimate and communicate loss exposure. | Write the scope memo so teams can see when ISO/IEC 27005 is the implementation structure, when FAIR controls the obligation or assurance question, and where evidence can be reused without changing the source test. |
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| Who must act | ISO/IEC 27005 ownership should sit with the team that can operate the relevant management system, control process, risk method, supplier relationship, incident process, privacy process, or AI governance scope. | FAIR ownership should follow that source's role model, such as regulator-facing accountable body, service organization, framework owner, provider, customer, processor, deployer, supplier, or risk owner. | Do not copy owners from one side to the other; map accountable owners, reviewers, and approvers separately. |
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| Trigger or threshold | ISO/IEC 27005 work is triggered by scope definition, implementation, certification readiness, customer assurance, control gaps, incidents, supplier changes, or management review. | FAIR work is triggered by its own legal, assurance, framework, contract, customer, or risk-management event. | Use the trigger to decide whether the question belongs in an ISO/IEC 27005 risk-management record, a FAIR analysis, or both. Route implementation and management-system questions to ISO/IEC 27005, and route loss-exposure analysis to FAIR. |
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| Core obligations | ISO/IEC 27005 is guidance for managing information security risks. It helps teams define scope, roles, evidence, operating cadence, monitoring, review, and improvement. | FAIR is a quantitative information-risk analysis model. It helps teams estimate and communicate loss exposure, rather than defining a management-system process. | Translate both sides into a single task register only after labeling which requirement or guidance source each task satisfies. |
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| Evidence and records | ISO/IEC 27005 evidence should show the process operating: owners, decisions, registers, control records, test results, review minutes, audit samples, or corrective actions. | FAIR evidence should match its own proof model, such as regulatory records, attestation evidence, framework profiles, risk analysis, or contractual assurance. | Build an evidence matrix with one row per claim and columns for source, owner, artifact, date, review trigger, and reuse permission. |
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| Timing and cadence | ISO/IEC 27005 timing follows implementation, audit, certification, review, supplier, incident, or change cycles rather than a single universal deadline. | FAIR timing follows the legal effective date, assurance period, framework version, contract milestone, or publication lifecycle that applies to that side. | Track dates separately so an ISO review cycle does not get mistaken for a statutory deadline or assurance reporting period. |
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| Enforcement or assurance route | ISO/IEC 27005 is guidance and is not directly certifiable; it is usually tested indirectly through ISO/IEC 27001 certification audits, internal audits, customer assurance, management review, or governance review when the organization adopts it as supporting risk-management guidance. | FAIR may be enforced, audited, attested, assessed, or used voluntarily depending on whether it is law, assurance criteria, a framework, or guidance. | Separate audit readiness from legal compliance and from voluntary framework maturity so executives see the actual consequence of gaps. |
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| Overlap and reuse | ISO/IEC 27005 can supply reusable management-system evidence, control operation records, risk decisions, and review outputs. | FAIR can reuse some of that evidence when the control, process, risk, or duty is genuinely the same. | Reuse evidence only after checking scope, actor, date, data type, service, supplier, and acceptance criteria; otherwise keep separate records. |
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| Practical decision rule | Use ISO/IEC 27005 when the main work is building, operating, reviewing, or proving a management-system or standards-based control process. | Use FAIR when the main work is satisfying that side's law, assurance route, framework outcome, risk method, or external reporting expectation. | If both apply, keep the primary obligation visible and use the other side as supporting structure, not as a substitute source. |
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