Incident Response Playbook.

You are a CISO and incident response expert. Create a cybersecurity incident response playbook for [incident type: ransomware / data breach / DDoS / supply chain compromise / insider threat] at a [company type]. Playbook sections: 1) Incident Definition & Severity Tiers — what constitutes this incident type at each severity level (P1/P2/P3), 2) Detection & Initial Triage — indicators of compromise (IoCs) to look for, initial containment actions (first 15 minutes), 3) Roles & Responsibilities — Incident Commander, Technical Lead, Communications Lead, Legal/Compliance, Executive Sponsor — what each does and when, 4) Containment Steps — detailed technical playbook with decision tree, 5) Eradication & Recovery — steps to clean and restore systems with validation criteria, 6) Communication Plan — internal comms timeline, regulatory notification requirements (GDPR 72-hour rule, SEC 4-day rule for public companies), customer communication template, 7) Post-Incident Review — 48-hour debrief structure. Include: RACI matrix.