• Breanainn Dagmær
• January 7, 2025
• No Comments

Introduction
A rapid, well‑coordinated response limits damage, preserves evidence, and speeds recovery. This guide provides a practical sequence of actions for teams to follow immediately after detecting a cyber attack, through containment, recovery, and lessons learned.

1. Activate the incident response plan

• Notify the incident response (IR) team and senior stakeholders per the runbook.
• Declare incident severity and escalate to executive/Legal/PR/Compliance as defined.
• Open an incident channel (secure chat, war‑room) and assign clear roles: incident commander, forensic lead, communications, legal, and technical owners.

1. Triage and contain (first 1–24 hours)

• Isolate affected systems to prevent lateral movement (network segmentation, block IPs, disable compromised accounts).
• Preserve volatile evidence: capture memory, disk images, relevant logs, and network captures.
• Disable backdoors and external access points discovered during triage (but avoid disruptive eradication before forensics).
• Implement short‑term mitigations: firewall rules, ACLs, halt automated syncs to backups if they risk encryption.

1. Assess scope and impact

• Identify initial access vector (phishing, RDP, vulnerability) and list all affected assets, users, and data stores.
• Determine business impact levels: systems down, data exfiltrated, regulatory exposure, customer impact.
• Triage sensitive data exposure and prioritize containment of systems holding critical or regulated data.

1. Engage external partners (as needed)

• Contact legal counsel and cyber insurance contacts to understand obligations and coverage.
• Engage experienced digital forensics/IR vendors if internal capacity is limited or legal/regulatory complexity exists.
• Notify law enforcement where applicable (depending on jurisdiction and incident type).

1. Communicate carefully and compliantly

• Follow preapproved communication templates; avoid releasing speculative technical details.
• Notify internal teams and affected business units with actionable instructions (e.g., change passwords, disconnect devices).
• Prepare external notifications as required by law (breach notification rules) and by contractual obligations; coordinate PR and legal for customer messaging.

1. Eradicate and remediate (after containment & evidence collection)

• Remove malware, close exploited vulnerabilities (patch, disable services), and rotate compromised credentials and keys.
• Rebuild or restore affected systems from known‑good images or verified backups; avoid reintroducing compromised artifacts.
• Harden systems: apply least privilege, enable MFA, tighten logging and monitoring, and close exposed remote access channels.

1. Recover operations safely

• Restore services incrementally, prioritizing critical business functions; validate integrity before returning systems to production.
• Monitor restored systems for recurrence using enhanced detection rules and increased telemetry.
• Extend heightened monitoring period (days to weeks) to detect residual access or secondary actions.

1. Conduct forensic analysis and evidence handling

• Complete a root‑cause analysis documenting timelines, attack techniques, indicators of compromise (IOCs), and scope.
• Preserve chain‑of‑custody for legal or regulatory purposes.
• Share vetted IOCs with detection teams and threat intelligence stakeholders.

1. Post‑incident review and remediation plan

• Run a post‑mortem with technical and business stakeholders to identify gaps in controls, processes, and detection.
• Produce a prioritized remediation roadmap with owners, deadlines, and measurable success criteria.
• Update the incident response plan, playbooks, and runbooks based on lessons learned.

1. Regulatory, contractual, and customer obligations

• Complete required breach notifications and regulatory filings within mandated windows.
• Provide remediation attestations or forensic summaries to affected customers or partners as contracted.
• Track and document all actions for audits and potential legal proceedings.

1. Rebuild resilience and prevention controls

• Harden environments: patching cadence, identity controls (MFA, privileged access management), network segmentation, and endpoint protections (EDR).
• Improve visibility: centralize logs, enable threat hunting, and tune SIEM/alerts.
• Run tabletop exercises and red team engagements to validate improvements and staff readiness.

1. Employee support and training

• Provide guidance for employees impacted (credential resets, device replacements).
• Increase targeted training (phishing simulations, privileged user awareness) based on the incident vector.

1. Share lessons externally (where appropriate)

• Contribute anonymized IOCs and TTPs to trusted communities/ISACs to help others defend against the same adversary.
• Publish a transparent post‑incident summary for customers if it supports trust and complies with legal advice.

Conclusion
Effective post‑attack handling balances speed, evidence preservation, and careful communication. Follow a repeatable IR process: detect, contain, analyze, eradicate, recover, and learn. Preparedness—documented playbooks, tested backups, and practiced response teams—turns incidents from crises into manageable events.