Purple teaming: running a detection test that changes something

// Understanding the Value of Active Changes

Purple teaming seeks to enhance collaboration between red and blue teams. One effective approach is to run detection tests while implementing changes in real time. This not only tests your detection mechanisms but also exposes potential gaps and weaknesses in your incident response.

// Setting Up a Detection Test with Active Changes

1. Define Objectives: Establish what you want to achieve from the detection test. Common objectives include testing specific detection rules, validating SIEM accuracy, and assessing the effectiveness of incident response procedures.

2. Select a Change Mechanism: Choose a change that will alter the system state. This could be a configuration change, a new deployment, or an intentional vulnerability. For example, if using a web application, consider modifying authentication parameters to trigger specific security alerts.

3. Document the Existing State: Before making any changes, create a baseline. This may include taking snapshots of logs, configurations, and current user permissions. For instance:

   # Capture current firewall rules
   iptables -L -n -v > /path/to/firewall_rules_baseline.txt

4. Implement the Change: Execute the planned change in a controlled environment. Make sure to communicate with involved teams about the timing and scope of these changes to prevent confusion during testing.

5. Monitor Detection Mechanisms: As changes occur, closely monitor your detection systems. This includes SIEM alerts, intrusion detection/prevention systems (IDS/IPS), and any custom scripts you have in place. Check the logs for anomalies or alerts triggered by the change.

   # Monitor SIEM for alerts triggered by new deployment
   cat /var/log/syslog | grep 'ALERT'

6. Evaluate Detection Efficacy: After the test, analyze whether the detection mechanisms reacted as expected. Were the appropriate alerts triggered? Did false positives or negatives occur? This analysis will guide you in refining detection rules and incident response workflows.

// Common Pitfalls and How to Avoid Them

• Lack of Communication: Ensure both red and blue teams understand the objectives and changes being made. Miscommunication can lead to missed alerts or unnecessary escalations.

• Insufficient Documentation: Always document the initial state and any changes made. This is critical for post-test analysis and for rolling back changes if necessary.

• Ignoring Contextual Factors: Changes should mimic real-world scenarios as closely as possible. Avoid using overly simplistic or artificial changes that do not reflect actual threat vectors.

// Example Scenario

Consider a scenario where your organization has just deployed a new version of a web application. You suspect that the new deployment may introduce security vulnerabilities, and you want to test your detection capabilities.

1. Objective: Test if the new deployment can be detected by your WAF (Web Application Firewall).

2. Change Mechanism: Modify an authentication API endpoint to trigger authentication bypass attempts.

3. Current State: Capture existing WAF rules and configurations:

   curl -X GET http://<WAF_IP>/rules -H 'Authorization: Bearer <token>'

4. Implement Change: Update the API endpoint and deploy the new version of the web application.

5. Monitor: Watch the WAF logs actively:

   tail -f /var/log/waf.log | grep 'bypass'

6. Evaluate: Review the logs to see if the WAF detected the changes and logged them appropriately.

// Defensive Implications

By actively testing detection mechanisms during changes, you can enhance your security posture. This approach not only uncovers blind spots but also improves the overall resilience of your defenses. It allows teams to adapt their incident response strategies based on real-time changes, ultimately making detection mechanisms more robust.

Checklist for Active Change Detection Testing

• [ ] Define clear objectives for the test.
• [ ] Select an appropriate change mechanism.
• [ ] Document the existing state before changes.
• [ ] Communicate changes to the involved teams.
• [ ] Implement changes accordingly.
• [ ] Monitor detection systems in real time.
• [ ] Analyze results and refine detection mechanisms.

Running detection tests with active changes is an effective method to validate your defenses while honing your incident response capabilities. Always remember to conduct these tests in a controlled, authorized environment to ensure compliance and safety.

--- // FIELDOPS REPORT AUTHORIZED BY: Bruce H. //