Ransomware examples: attacks, types and groups

**Executive summary:** This briefing summarizes high-profile ransomware incidents (WannaCry, NotPetya, Colonial Pipeline, Cl0p/MOVEit, Change Healthcare), explains ransomware types and the ransomware-as-a-service model, identifies active groups and common entry vectors (unpatched internet-facing systems, compromised credentials, phishing, third-party compromises), and cites official advisories and mitigations including patching, MFA, and offline backups.