Enhancing detection through purple teaming exercises

// Introduction

Purple teaming is not just a buzzword; it’s a strategy to enhance your organization's security posture through collaboration between red and blue teams. By running detection tests that also change something within the environment, you can uncover weaknesses in both detection capabilities and incident response workflows.

// Defining the Objective

The goal is to conduct an exercise where the blue team tests their detection mechanisms against red team tactics, while simultaneously making adjustments based on what they learn. This creates a feedback loop that benefits both teams. One common scenario is simulating an attacker creating persistence mechanisms in a Linux environment.

// Setting Up the Test Environment

To begin the exercise, ensure you have a controlled, disposable environment. For Linux, set up a virtual machine with a clean installation. Use the following configuration for persistence mechanisms:

1. Create a simple malicious script that runs on startup. Save it as /usr/local/bin/malicious_script.sh:

   #!/bin/bash
   echo "Malicious activity running" >> /var/log/malicious.log

2. To ensure it runs at startup, add it to the systemd service:

   echo -e "[Unit]\nDescription=Malicious Script\n\n[Service]\nExecStart=/usr/local/bin/malicious_script.sh\n\n[Install]\nWantedBy=multi-user.target" | sudo tee /etc/systemd/system/malicious.service
   sudo systemctl enable malicious.service

// Running the Exercise

Phase 1: Red Team Activity

Initiate the red team activity by executing the malicious script and ensure it’s properly logging output. This simulates a persistence mechanism that an attacker might utilize. Monitor the system logs with:

sudo tail -f /var/log/malicious.log

Phase 2: Blue Team Detection

The blue team should have their detection tools in place, such as a SIEM. Configure your SIEM to look for unusual service creation events. Here’s a sample query for ElasticSearch:

{
  "query": {
    "bool": {
      "must": [
        { "match": { "event.action": "create" } },
        { "match": { "event.type": "service" } }
      ]
    }
  }
}

Phase 3: Analysis and Feedback

As the red team executes their persistence mechanism, the blue team should analyze logs and attempt to correlate findings. This phase often reveals gaps in detection capabilities:

• Did the SIEM capture the service creation event?
• Were there alerts generated?
• How quickly did the blue team respond?

// Common Mistakes to Avoid

• Inadequate Logging: Ensure that logging is comprehensive. Missing logs can lead to undetected persistence methods.
• Ignoring Response Time: Focus on how quickly the blue team identifies and responds to the activity. Delay can lead to further exploitation.
• Lack of Communication: Keep channels open between teams throughout the exercise to ensure real-time feedback and adjustments.

// Defensive Implications

From the insights gained, adjust your detection capabilities as follows:

• Implement alerts for unauthorized service creations.
• Conduct regular reviews of persistent mechanisms in your environment. The systemctl command can help track services:

systemctl list-units --type=service --state=running

// Checklist for Purple Teaming Exercises

• [ ] Define clear objectives for both teams.
• [ ] Establish a controlled environment.
• [ ] Ensure comprehensive logging and monitoring tools are in place.
• [ ] Schedule regular feedback sessions post-exercise.
• [ ] Update defenses based on findings.

// Conclusion

Conducting purple team exercises is a practical approach to improving your security posture. By integrating detection tests that lead to real changes in your environment, you not only enhance your capabilities but also prepare for future threats. Make sure to run these exercises in a controlled and disposable range, maintaining the integrity of your actual assets. Remember, the curriculum at DaemonCore Academy is free and designed for hands-on security engineering training.