TL;DR
Penetration tests are vital for cyber security, but you want to make sure they don’t actually compromise your systems. This guide shows how to control the scope of a pen test, limit damage, and learn from the results without causing real disruption.
How to Prevent Pen Testers From Compromising Your System
- Define Clear Scope & Rules of Engagement: This is the most important step. A vague brief invites problems.
- In-Scope Systems: Explicitly list which servers, applications, and network segments are allowed to be tested.
- Out-of-Scope Systems: Equally importantly, state what cannot be touched (e.g., production databases, payment gateways).
- Testing Techniques Allowed/Disallowed: Specify permitted methods – e.g., black box testing only, no denial of service attacks, no social engineering against specific staff.
- Time Window: Set a precise start and end date/time for the test.
- Contact Information: Provide 24/7 contact details for your security team during the pen test.
- Network Segmentation: Isolate critical systems.
- If possible, create a separate testing environment that mirrors production but isn’t directly connected to live data. This is ideal.
- Use firewalls and access control lists (ACLs) to restrict the pen tester’s movement even within the in-scope network. For example, only allow connections from the pen tester’s IP address(es) to specific ports on target systems.
# Example firewall rule (iptables - Linux) iptables -A INPUT -p tcp --dport 80 -s [Pen Tester IP] -j ACCEPT iptables -A INPUT -p tcp --dport 443 -s [Pen Tester IP] -j ACCEPT iptables -A INPUT -j DROP # Drop everything else
- Data Protection & Masking: Protect sensitive information.
- Anonymise Data: Replace real customer data with fake, but realistic-looking, data in the testing environment.
- Tokenisation: Use tokens instead of actual credit card numbers or other PII (Personally Identifiable Information).
- Log Scrubbing: Ensure logs don’t contain sensitive information that could be exposed during the test.
- Account Control & Monitoring: Limit tester privileges and watch what they do.
- Dedicated Test Accounts: Provide testers with accounts specifically for the pen test, with minimal necessary permissions. Avoid using real user credentials.
- Privilege Escalation Restrictions: If privilege escalation is allowed (and it should be clearly stated in the rules of engagement), monitor closely and limit the scope.
- Real-time Monitoring: Use Security Information and Event Management (SIEM) systems or intrusion detection/prevention systems (IDS/IPS) to track tester activity.
# Example using Wireshark to monitor network traffic wireshark -i eth0 # Replace eth0 with your network interface
- Backup & Recovery Plan: Be prepared for the worst.
- Recent Backups: Ensure you have up-to-date backups of all in-scope systems.
- Recovery Procedures: Document clear steps to restore systems if something goes wrong. Test these procedures *before* the pen test begins.
- Rollback Plan: Have a plan to quickly revert any changes made by the testers if necessary.
- Communication Protocol: Establish clear communication channels.
- Regular Check-ins: Schedule regular meetings with the pen testing team to discuss progress and address any concerns.
- Emergency Contact Procedure: Define a process for immediate notification if a critical vulnerability is discovered or if the test exceeds its boundaries.
- Reporting Process: Agree on how findings will be reported (e.g., written reports, debriefing sessions).
- Post-Pen Test Review & Remediation: Learn from the experience.
- Detailed Report Analysis: Carefully review the pen test report to understand all identified vulnerabilities and their severity.
- Prioritised Fixes: Address vulnerabilities based on risk level, starting with the most critical issues.
- Lessons Learned: Document what worked well during the pen test and what could be improved for future engagements.