tools-only Network Security Incident Response
Overview
This document provides comprehensive procedures for identifying, containing, and resolving network security incidents to protect organizational assets and data.
Purpose
- Rapidly identify and respond to security threats
- Minimize impact and damage from security incidents
- Preserve evidence for forensic analysis
- Ensure compliance with regulatory requirements
- Maintain business continuity during incidents
Incident Classification
Severity Levels
| Level | Description | Response Time | Examples |
|---|---|---|---|
| Critical | Immediate threat to business operations | 15 minutes | Data breach, ransomware, critical system compromise |
| High | Significant security risk | 1 hour | Malware outbreak, unauthorized access, DDoS attack |
| Medium | Moderate security concern | 4 hours | Suspicious network activity, policy violations |
| Low | Minor security issue | 24 hours | Failed login attempts, minor policy violations |
Response Process
1. Detection and Analysis (0-30 minutes)
- Initial Alert: Security tools, user reports, or monitoring systems
- Triage Assessment: Determine incident severity and classification
- Evidence Collection: Preserve logs, screenshots, and system states
- Impact Assessment: Evaluate affected systems and potential data exposure
Detection Sources
- SIEM alerts and monitoring tools
- Antivirus and endpoint detection systems
- Network intrusion detection systems (IDS)
- User reports and help desk tickets
- Automated security scanning tools
2. Containment (30 minutes - 2 hours)
- Immediate Actions:
- Isolate affected systems from network
- Disable compromised user accounts
- Block malicious IP addresses and domains
- Preserve system images for forensic analysis
Short-term Containment
- Network segmentation and traffic blocking
- System isolation and quarantine
- Account lockouts and password resets
- Temporary workarounds for business continuity
Long-term Containment
- System patching and security updates
- Enhanced monitoring and logging
- Additional access controls and restrictions
- Temporary security measures implementation
3. Eradication (2-8 hours)
Threat Removal:
- Remove malware and malicious files
- Close security vulnerabilities
- Apply security patches and updates
- Strengthen security configurations
System Hardening:
- Update security policies and procedures
- Implement additional security controls
- Enhance monitoring and detection capabilities
- Review and update access permissions
4. Recovery (4-24 hours)
System Restoration:
- Restore systems from clean backups
- Rebuild compromised systems
- Implement security improvements
- Gradual return to normal operations
Validation Steps:
- Security testing and validation
- Functionality verification
- Performance monitoring
- User access testing
5. Lessons Learned (1-2 weeks post-incident)
- Post-Incident Review:
- Timeline analysis and documentation
- Response effectiveness evaluation
- Process improvement recommendations
- Training and awareness updates
Incident Response Team
Core Team Members
| Role | Responsibilities | Contact |
|---|---|---|
| Incident Commander | Overall response coordination | security-lead@company.com |
| Security Analyst | Technical analysis and investigation | security-team@company.com |
| Network Engineer | Network isolation and containment | network-team@company.com |
| System Administrator | System recovery and restoration | sysadmin@company.com |
| Legal Counsel | Regulatory compliance and notifications | legal@company.com |
| Communications Lead | Internal and external communications | comms@company.com |
Escalation Contacts
- CISO: +1-800-SEC-EXEC
- IT Director: +1-800-IT-LEAD
- Legal: +1-800-LEGAL-01
- External Security Firm: +1-800-SEC-HELP
Communication Procedures
Internal Communications
- Immediate: Security team and incident commander
- 30 minutes: IT leadership and affected department heads
- 1 hour: Executive leadership and legal team
- 2 hours: All staff (if organization-wide impact)
External Communications
- Regulatory Bodies: Within 72 hours (GDPR requirement)
- Law Enforcement: If criminal activity suspected
- Customers/Partners: As required by contracts and regulations
- Media: Only through designated spokesperson
Tools and Resources
Security Tools
- SIEM Platform: Splunk, IBM QRadar, or Microsoft Sentinel
- Endpoint Detection: CrowdStrike, Carbon Black, or Microsoft Defender
- Network Monitoring: Wireshark, SolarWinds, or PRTG
- Forensic Tools: EnCase, FTK, or Volatility
- Communication: Microsoft Teams or Slack for coordination
Documentation Templates
- Incident tracking spreadsheet
- Evidence collection forms
- Timeline documentation template
- Post-incident report template
- Regulatory notification templates
Compliance and Reporting
Regulatory Requirements
- GDPR: Data breach notification within 72 hours
- HIPAA: Security incident documentation and reporting
- SOX: Financial system security incident reporting
- PCI DSS: Payment card data security incident procedures
Documentation Requirements
- Detailed incident timeline
- Evidence collection and chain of custody
- Response actions taken
- Impact assessment and damages
- Lessons learned and improvements
Training and Preparedness
Regular Activities
- Monthly: Security awareness training
- Quarterly: Incident response tabletop exercises
- Annually: Full-scale incident response simulation
- Ongoing: Security tool training and certification
Knowledge Areas
- Threat landscape and attack vectors
- Security tool operation and management
- Forensic analysis techniques
- Legal and regulatory requirements
- Communication and coordination skills
Best Practices
- Prepare in Advance: Maintain updated contact lists and procedures
- Act Quickly: Time is critical in security incident response
- Document Everything: Maintain detailed logs and evidence
- Communicate Clearly: Keep stakeholders informed appropriately
- Learn and Improve: Use incidents to strengthen security posture
Last Updated: September 2025 Document Owner: Information Security Team