Purple Teaming The Feedback Loop Security Needs

Level: Intermediate

Red + Blue = Purple

Red Teaming is "Blind Testing". The Blue Team doesn't know you are coming. This is great for testing response processes, but it is terrible for testing specific controls.

If I run a red team op and I don't use a specific technique (say, Kerberoasting) because I found an easier way (Phishing), you learn nothing about your defenses against Kerberoasting.

Purple Teaming is "Open Book Testing". Red and Blue sit in the same room (or Zoom call). Red says: "I am going to execute T1558.003 (Kerberoasting) now." Blue says: "Okay, executed. Let me check Splunk... nothing. Wait, I see a Event 4769. Let's build an alert for that."

It is high-speed, iterative improvement.

The Cycle of Purple

A typical Purple Team exercise focuses on a specific chain of behavior (e.g., "Ransomware Execution" or "Credential Dumping").

Phase 1: Emulate Red runs the attack atomic test. Example: mimikatz.exe privilege::debug sekurlsa::logonpasswords

Phase 2: Detect Blue looks at the SIEM/EDR. * Did we block it? (Prevention) * Did we see it? (Telemetry) * Did we get an alert? (Detection)

Phase 3: Tune If we missed it, fix it right now. Write the Sigma rule. Tune the EDR policy.

Phase 4: Re-Emulate Run the attack again. Did the alert fire? Yes? Success. Move to the next test.

Atomic Red Team & BAS

You don't need a super-hacker to start Purple Teaming. Use Atomic Red Team (by Red Canary). It's a library of scripts mapped to MITRE ATT&CK.

  • T1003.001 (LSASS Dump): procdump.exe -ma lsass.exe lsass.dmp
  • T1087 (Account Discovery): net user /domain

BAS (Breach and Attack Simulation) tools like Scythe, AttackIQ, or SafeBreach automate this. They run thousands of these tests continuously to ensure that a config change didn't accidentally break your detections.

Why Purple Teaming is the Future

Traditional Red Teaming is slow. You get one report a year. Purple Teaming is continuous.

It solves the "Silent Failure" problem. We often assume our AV is working. We assume our firewall is logging. But until you actually throw a packet at it and check the logs, you are just hoping.

Don't Hope. Verify.

Running Your First Exercise

  1. Pick a Topic: "Lateral Movement" is a good start.
  2. Pick 5 Techniques:
    • PsExec
    • WMI
    • WinRM
    • Pass-the-Hash
    • RDP Hijacking
  3. Get the People: You need one Red Teamer (to run the script) and one SOC Engineer (with console access).
  4. Timebox: 2 hours max.
  5. Execute.

You will be amazed at how many "guaranteed" detections fail on the first try. And you will feel great when you fix them on the spot.