Incident Response Manual for Worm Infection (Updated 2025)

This Incident Response Playbook for computer worm infections provides step-by-step guidance to detect, contain, remediate, and recover from such incidents. Updated to reflect modern SOC practices, this playbook also integrates automation, threat intelligence, and endpoint detection technologies to enhance response capabilities.

1. Preparation

Objective: Prepare the organisation to handle worm infections by establishing protocols, contacts, and monitoring tools.

Key Actions:

1. Define Roles and Responsibilities:
   Identify and document key actors in the incident response team, including SOC analysts, Incident Response (IR) leads, IT administrators, and communication officers.

   • Maintain a contact list for both internal and external stakeholders (e.g., CERT, external support providers).

2. Ensure Security Tools Are Operational:
   Verify that critical security tools, such as Endpoint Detection and Response (EDR), SIEM, antivirus, and network intrusion detection systems (IDS/IPS), are fully functional and up to date.

3. Develop Documentation:
   Keep an updated inventory of assets, including network architecture diagrams and configurations for critical infrastructure.

4. Conduct Threat Monitoring:
   Stay informed about emerging malware threats through regular security intelligence updates and threat feeds.

2. Identification

Objective: Detect and verify the presence of a worm infection and determine its scope.

Detection Sources:

Analyse data from multiple sources to identify indicators of compromise (IoCs), including:

• Antivirus and EDR alerts

• IDS/IPS logs

• Unusual network traffic (e.g., high outbound connections or packet rates)

• Authentication failures (e.g., locked accounts due to brute force attacks)

• System performance issues (e.g., high CPU usage, system freezes)

Steps:

1. Confirm Infection Indicators:
   Use forensic tools and threat intelligence to validate the presence of the worm.

2. Analyse Propagation Vectors:
   Identify how the worm is spreading (e.g., through network shares, removable devices, or exploits).

3. Assess Impact:
   Define the scope of the infection, including affected systems, networks, and business processes. Notify the Chief Information Security Officer (CISO) and, if required, national CERTs or regulators.

3. Containment

Objective: Limit the spread of the worm to prevent further damage.

Steps:

1. Isolate Affected Systems:

   • Disconnect infected systems or network segments from the internal network and the Internet.

   • Implement network access control (NAC) to quarantine devices attempting suspicious activity.

2. Disable Propagation Channels:

   • Block protocols and services that the worm may exploit, such as SMB (Server Message Block) or RDP (Remote Desktop Protocol).

   • Apply security rules in firewalls and endpoint protection policies.

3. Implement Temporary Measures:

   • If business-critical operations cannot be halted, apply validated exceptions (e.g., controlled network paths) to maintain limited functionality while monitoring for threats.

4. Monitor Containment Progress:
   Use SIEM dashboards, antivirus consoles, and support call logs to track infection spread and verify containment.

5. Mobile Devices and BYOD:
   Ensure that personal devices (e.g., laptops, smartphones, USB drives) are not being used as propagation vectors. Enforce security policies for remote access.

4. Remediation

Objective: Eradicate the worm from the environment and prevent reinfection.

Steps:

1. Identify Disinfection Tools:
   Use the following resources to plan remediation:

   • Updated antivirus and EDR signatures.

   • YARA rules and automated threat hunting tools (e.g., Chainsaw, ThorLite, Loki).

   • Threat intelligence reports.

2. Develop a Disinfection Process:
   Validate the process with internal teams and external experts (e.g., CERT or SOC partners). This process may include:

   • Automated removal via security tools.

   • Manual disinfection for critical systems.

3. Test Remediation:

   • Test the disinfection process on non-production systems to ensure no impact on operations.

   • Confirm that all malicious files and registry changes are removed.

4. Deploy Remediation:
   Apply the disinfection process across the affected environment. Methods include:

   • Automated patch management (e.g., WSUS for Windows).

   • Group Policy Objects (GPO) to enforce security settings.

   • Manual intervention where necessary.

5. Close Vulnerability Gaps:
   Address any weaknesses (e.g., unpatched software, weak access controls) that enabled the worm infection.

5. Recovery

Objective: Restore systems to normal operations in a secure and controlled manner.

Steps:

1. Verify Steps:
   Ensure that all remediation steps have been completed and approved by senior security management.

2. Reintroduce Network Connections:

   • Reconnect isolated sub-networks incrementally, starting with internal systems.

   • Reconnect external connections (e.g., Internet access) only after ensuring that all devices are secure.

3. Monitor Systems:
   Perform enhanced monitoring for any signs of recurring infections. Use log analysis, threat detection, and EDR alerts to validate system stability.

4. Document Actions:
   Maintain records of recovery procedures, including timelines and responsible parties.

6. Lessons Learned

Objective: Improve future incident handling by documenting findings and implementing security improvements.

Steps:

1. Incident Reporting:
   Compile a detailed report that includes:

   • Initial cause and entry point of the infection.

   • Timeline of detection, containment, and remediation activities.

   • Key decisions and actions taken by the crisis management team.

2. Evaluate Performance:
   Identify what went well and what could be improved in the response process. Involve all relevant stakeholders in post-incident reviews.

3. Update Playbooks:
   Refine incident response playbooks and procedures based on lessons learned.

4. Strengthen Defences:
   Implement additional preventive measures, such as:

   • Enhanced network segmentation.

   • Employee training on malware threats.

   • Improved monitoring and alerting capabilities.

Conclusion

By following this updated playbook, SOC teams can effectively detect, contain, remediate, and recover from worm infections. Continuous improvement and integration with threat intelligence and modern security tools will ensure a strong defence against evolving malware threats.

Would you like further resources, such as templates for incident reports or containment strategies? Let us know!