TL;DR: Incident Response Lifecycle

Table of Contents

1. Preparation

Policies & Procedures: Develop or refine Incident Response (IR) policies, roles, and responsibilities so everyone knows how to act when an incident occurs.
Tools & Resources: Maintain ready-to-use security solutions, forensic toolkits, and log management systems.
Training & Awareness: Conduct regular training sessions and simulations (tabletop exercises) to keep your team prepared.

Detection of Indicators: Monitor for alerts and abnormal behavior (e.g., unusual login times, network traffic spikes).
Assess the Severity: Determine if it’s a genuine incident or a false alarm, and rate its potential impact on confidentiality, integrity, and availability.
Documentation: Record all initial findings, including timestamps and relevant logs (e.g., system logs, network captures).

Short-Term Containment: Immediately isolate or segment compromised systems to limit further damage (e.g., quarantining infected hosts, disabling malicious accounts).
Evidence Preservation: While containing, preserve critical data for forensic analysis (e.g., memory dumps, disk images).
Long-Term Strategy: Develop and implement broader containment measures (e.g., adjusting firewall rules, enhancing monitoring) as investigation continues.

Remove the Threat: Eliminate all malicious code, backdoors, or unauthorized accounts from affected systems.
Patch & Update: Apply security patches, adjust configurations, and address root causes to prevent recurrence.
Verification: Perform scans or tests to confirm that the threat is fully removed and no hidden traces remain.

Restore Systems: Bring systems back online methodically (often in stages). Confirm they are secured, hardened, and verified to be clean.
Monitor for Recurrence: Closely track network traffic, logs, and alerts for any indication of the threat re-emerging.
Documentation: Record all actions taken to restore operations, including timelines and individuals involved.

Review the Incident: Conduct a post-mortem to evaluate what happened, what worked, and where improvements are needed.
Update Procedures & Policies: Integrate lessons learned into IR plans, detection tools, and training modules.
Reporting & Sharing: When applicable, share relevant details with stakeholders, regulatory bodies, or ISACs (Information Sharing and Analysis Centers).

Preparation prevents being caught off guard.
Identification ensures you act quickly before threats spread.
Containment and Eradication help control damage and remove malicious elements.
Recovery enables a safe return to normal operations.
Lessons Learned drives continuous improvements, reducing future risk.