5.25 Assessment and decision on information security events
Requires information security events to be assessed and a decision taken on whether each event is to be categorised as an information security incident.
5
artefacts
1
held by a system
3
at each review
hard
to go live
Document repository
where the evidence lives
teal = a system already holds it · olive = produced at each review
system holds itEvidence a system already holds
- The point of contact or triage function receiving events from all sources, including monitoring, users and third parties · SIEM / log platform
periodic reviewEvidence produced at each review
- Records of events assessed in the period, including those assessed as not incidents, with the reason recorded · Document repository
- Evidence of who performed the assessment and that they were competent and authorised to do so · Document repository
- Evidence of reassessment where new information changed the initial categorisation · Document repository
governing documentDocuments that govern the control
- The criteria used to decide whether an event is an incident, and the severity scale applied · Document repository
First move
Mostly documents and reviews. Pull the 1 system-held artefact from your SIEM / log platform on a schedule; put the documents under version control with an owner and review date, and log each review as a dated record with a named reviewer.
Common gaps auditors find
- Only confirmed incidents are recorded, so the events dismissed at triage leave no audit trail and the decision cannot be reviewed
- Categorisation criteria informal, so the same event is treated differently depending on who is on shift
- Events from users and from suppliers entering a different route with no consistent triage
- Severity assigned at open and never revised as the picture changes
Do this for your whole sheet
Paste the rows you run your controls from and get this mapping for every control at once, with the periodic-review ones flagged and a first move per row. No account for the first run.
Build my evidence sheet5.24 Information security incident management planning and preparation · 5.26 Response to information security incidents