Assumptions: cluster is HDFS-based (YARN/Spark clients), several DataNodes encrypted, NameNode metadata may be exfiltrated, backups exist (fsimage/edits, snapshots, external backups), organization has IR, legal and SRE teams.
- Triage & Containment (first 0–4 hours)
- Isolate affected hosts from network (remove from LB, block by IP/MAC in network and SDN). Do NOT power-cycle encrypted nodes to preserve volatile evidence.
- Quarantine NameNode and Secondary/JournalNodes: restrict client access (read-only) and disable exposures (Kerberos/TLS endpoints).
- Capture volatile state from live systems (memory, running processes, network connections, open files) using standard forensic tools; record timestamps and operator actions.
- Forensic Preservation (0–48 hours)
- Create disk images of affected DataNodes and any suspicious control-plane hosts (bit-for-bit, using dd/FTK/imager) and verify checksums.
- Collect logs: HDFS, OS (syslog, auth), YARN, Ranger/Atlas, Kerberos KDC, network flow, NIC captures. Preserve NameNode fsimage and edits logs with timestamps.
- Identify initial compromise vector (RDP/SSH keys, misconfigured S3, exposed web UI, supply-chain) and scope lateral movement.
- Recovery from Backups (24–72+ hours)
- Validate backups: verify checksums of fsimage/edits and block reports from safe storage (air-gapped or immutable snapshots).
- Stand up clean HDFS control plane on hardened hosts (fresh OS images). Restore NameNode state from last known-good fsimage+edits into an isolated cluster.
- Rebuild DataNodes by restoring blocks from immutable object store backups or snapshots. If full block backup missing, leverage HDFS snapshots and replication survivors; mark corrupted/Ransomware-encrypted blocks as corrupt and trigger HDFS to replicate from healthy replicas.
- Reconcile namespace: run hdfs fsck and use dfsadmin recoverLease/block reporting to repair namespace. Use blockfixer and fsimage edits reconciliation.
- Integrity & Completeness Verification
- Verify block checksums, file-level checksums (if maintained), and HDFS metadata consistency. Run iterative hdfs fsck until no missing blocks.
- Sample critical datasets; run downstream ETL unit tests and checksum comparisons against pre-incident baselines.
- Maintain audit trail of restored files and unverifiable or missing data; classify impact.
- Legal & Regulatory Notification
- Notify internal Legal, Compliance, and CISO immediately. Prepare incident facts: timeline, data classes exfiltrated, affected records count.
- Follow jurisdictional breach notification rules (e.g., GDPR, CCPA) and regulator timelines; preserve chain-of-custody for potential law enforcement.
- Engage law enforcement and external forensics provider if required.
- Hardening & Prevent recurrence (2–8 weeks)
- Rotate keys, Kerberos principals, service accounts, and any exposed credentials. Revoke compromised certificates.
- Patch & baseline hosts; enforce immutable infrastructure (golden images), configuration management, and automated attestations.
- Network segmentation: isolate data plane from compute and admin networks, limit DataNode admin ports via ACLs.
- Enforce least privilege for HDFS ACLs and Ranger policies; enable encryption at rest (HDFS encryption zones with KMS) and in-transit (TLS).
- Enable immutable, offsite/backups with write-once-read-many (WORM) storage and frequent fsimage snapshotting to air-gapped storage.
- Improve detection: deploy EDR, IDS/IPS, HDFS-specific anomaly detection (unexpected block deletes/renames), enable audit logging to centralized SIEM with long retention.
- Run tabletop exercises and update IR runbooks; implement backup restoration drills and SLAs.
Metrics & Acceptance
- Recovery objective: RTO for control-plane (<24–48h), RTO for critical datasets per SLAs, RPO defined by backup cadence.
- Post-incident: zero repeat incidents over 90 days, successful restore tests, reduced mean-time-to-detect.
This plan balances immediate containment and evidence preservation with safe restoration of HDFS namespace and blocks, legal compliance, and systemic hardening to reduce future risk.
