Vulnerability Patching: A Practical Guide

TL;DR

Regularly patching vulnerabilities is vital for cyber security. This guide covers planning, testing, deployment and verification to minimise risk during patch cycles.

1. Planning Your Patch Cycle

1. Inventory: Know what you have! Create a detailed list of all hardware and software assets. Include versions and support status. Use automated discovery tools if possible.
2. Risk Assessment: Prioritise vulnerabilities based on severity (CVSS score), exploitability, and impact to your business. Focus on critical systems first.
3. Patch Source Identification: Determine where you get patches from – vendor websites, security advisories, or a patch management system.
4. Schedule: Establish a regular patching schedule (e.g., monthly). Consider emergency out-of-band patching for zero-day exploits.

2. Testing Before Deployment

1. Lab Environment: Set up a test environment that mirrors your production setup as closely as possible. This is crucial!
2. Patch Application: Apply the patch to the test environment. Follow vendor instructions carefully.
3. Functional Testing: Verify core functionality remains intact after patching. Test key applications and services.
4. Regression Testing: Check for unintended consequences or compatibility issues with other systems.
5. Performance Monitoring: Observe system performance (CPU, memory, network) to identify any degradation caused by the patch.

3. Deployment Strategies

1. Staged Rollout: Deploy patches in phases – a small group of users/systems first, then gradually expand.
2. Maintenance Window: Schedule patching during off-peak hours to minimise disruption.
3. Backup Before Patching: Always create backups before applying any patch. This allows for quick rollback if needed.
4. Automated Patch Management Tools: Consider using tools like WSUS, SCCM, or third-party solutions to automate the patching process.

   # Example of checking patch status with PowerShell (Windows)

   Get-HotFix | Where {$_.Source -like "*KB4512345*"} 

5. Rollback Plan: Have a documented rollback procedure in case of issues. Know how to revert the patch quickly.

4. Verification and Reporting

1. Post-Patch Scanning: Use vulnerability scanners to confirm the vulnerability has been successfully patched.
2. Log Monitoring: Monitor system logs for any errors or anomalies after patching.
3. User Feedback: Collect feedback from users about any issues they encounter.
4. Documentation: Keep detailed records of all patches applied, testing results, and any issues encountered. This is important for auditing purposes.

5. Ongoing Maintenance

• Stay Informed: Subscribe to security advisories from your vendors.
• Regular Reviews: Periodically review your patching process and update it as needed.
• Cyber Security Awareness Training: Educate users about the importance of patching and reporting suspicious activity.