security-cheatsheets/infosec/incident-response.md
2025-04-15 00:07:33 -06:00

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Security Incident Response Cheatsheet

Phase Actions Tools/Commands Documentation
Preparation
Asset inventory Document critical systems nmap -sP 192.168.1.0/24 Asset register
Baseline establishment Record normal behavior top, netstat -tuln Baseline document
IRT contacts Establish escalation paths N/A Contact sheet
Response kit Prepare forensic tools FTK, volatility, wireshark Kit checklist
Detection & Analysis
Initial triage Verify incident occurrence grep 'Failed password' /var/log/auth.log Incident ticket
Scope determination Identify affected systems lsof -i, netstat -antp Scope document
Evidence collection Capture volatile data memory_dump.sh, dd if=/dev/sda of=disk.img Evidence log
Timeline creation Establish sequence of events log2timeline.py Timeline document
Containment
Short-term containment Isolate affected systems Network segregation, iptables -A INPUT -s malicious_ip -j DROP Containment log
System backup Create forensic copies dd, FTK Imager Backup verification
Long-term remediation Patch vulnerabilities apt update && apt upgrade Patch log
Eradication
Malware removal Eliminate persistence find / -name "suspicious_file", AV scan Cleanup report
Vulnerability patching Address security gaps yum update package, apt install security-patch Patch verification
System hardening Strengthen security posture chmod 600 /etc/shadow, ufw enable Hardening checklist
Recovery
System restoration Return to operation Restore from backup, service start Recovery log
Monitoring Watch for repeat incidents SIEM alerts, tail -f /var/log/syslog Monitoring plan
Validation testing Verify system integrity Penetration test, tripwire --check Test results
Lessons Learned
Documentation Complete incident report N/A Final report
Process improvement Update response procedures N/A Updated playbooks
Team debrief Review response effectiveness N/A Debrief minutes

Key Evidence Collection Commands

Data Type Linux Windows macOS
Running processes ps aux tasklist /v ps aux
Network connections netstat -antup netstat -ano netstat -anv
Open files lsof handle.exe lsof
Users logged in who query user who
Scheduled tasks crontab -l schtasks /query crontab -l
Process tree pstree tasklist /v /fi "username eq system" pstree
Loaded modules lsmod driverquery kextstat