Running a Purple Team Exercise

A purple team exercise is a structured process, not an ad-hoc hacking session. It follows a repeatable lifecycle:

• Plan — pick objectives, scope, and techniques
• Prepare — confirm telemetry, tooling, and authorization
• Execute — run techniques and observe live
• Analyze — classify outcomes and log gaps
• Improve — tune detections and re-test
• Report — capture metrics and actions

Treating it as a lifecycle is what makes results comparable over time.

Start with a clear, threat-informed objective. Vague goals ('test our security') produce vague results.

Good objectives are specific and measurable:

• Validate detection of credential access techniques used by ransomware affiliates
• Confirm visibility across the lateral movement tactic
• Measure mean time to detect for a known intrusion chain

Anchor the objective to a real threat actor or scenario relevant to your organization so the techniques you test are the ones you are likely to face.

Translate the objective into an ordered list of techniques with concrete procedures. This is your emulation plan.

Each entry should state the technique ID, the procedure, the expected telemetry, and the hypothesis being tested:

• Technique: T1003.001 LSASS Memory
• Procedure: dump LSASS via a benign test tool
• Expected telemetry: Sysmon Event ID 10 (process access to lsass.exe)
• Hypothesis: EDR alerts on unauthorized LSASS handle access

Before anything runs, secure written authorization and document the rules of engagement (ROE). This protects the team legally and operationally.

• Defined scope: hosts, networks, accounts in play
• Time windows and a clear stop condition
• Approved versus prohibited techniques
• Emergency contacts and an abort signal
• Data handling: never exfiltrate real sensitive data

Even cooperative testing can trip alarms or disrupt services, so the ROE must be explicit and signed off by stakeholders.

Confirm the basics work before the live session, otherwise you will waste it debugging logging.

• Verify endpoint agents and Sysmon are deployed and reporting
• Confirm logs reach the SIEM with acceptable latency
• Stage the emulation tooling (Atomic Red Team, Caldera)
• Prepare saved SIEM queries for each expected artifact

A quick smoke test, for example checking that a known event appears, validates the pipeline before real techniques begin.

During execution, run one technique at a time in a controlled window so cause and effect are unambiguous. Red narrates the action and notes the exact timestamp.

For example, executing an Atomic test for scheduled task persistence:

Immediately after execution, blue runs the prepared query and records what they see. Classify the outcome explicitly:

• Prevented — the action was blocked outright
• Alerted — a detection fired
• Logged only — evidence exists, no alert
• No telemetry — nothing was captured

Capture the timestamps of both the action and the alert so you can later compute time to detect.

Many emulation tools create artifacts: scheduled tasks, registry keys, files, or accounts. Clean up after each technique to keep the environment sane and avoid false future findings.

Atomic Red Team provides cleanup commands:

The defining feature of purple teaming is fixing gaps in the same session. When a technique is missed, the detection engineer drafts a rule and the team re-runs the technique to confirm it now fires.

• Gap found: scheduled task creation not alerting
• Draft rule on Event ID 4698 (task creation) with suspicious patterns
• Re-run the Atomic test
• Confirm the new rule fires, then record the win

This immediate iteration is far more effective than deferring fixes to a backlog.

Discipline in recording is what makes the exercise valuable later. For every technique log a structured result:

• Technique ID and procedure
• Outcome (prevented / alerted / logged / blind)
• Data source observed
• Detection rule that fired (or the new one created)
• Time to detect, and any follow-up action

Tools like VECTR store these results and let you compare runs over time to show measurable improvement.

End the exercise with a debrief while details are fresh. The output is a prioritized, actionable list, not a wall of text.

• What was detected, missed, and newly covered
• Detection gaps ranked by risk and likelihood
• Owners and due dates for each remediation
• Techniques to re-validate in the next cycle

Hand detection backlog items to engineering and schedule the next run. The exercise only pays off if the actions actually get implemented.

Test your understanding of how a purple team exercise is executed.

You can now run a purple team exercise end to end:

• Follow the plan, prepare, execute, analyze, improve, report lifecycle
• Set threat-informed objectives and a concrete emulation plan
• Secure authorization and ROE, and verify telemetry first
• Run one technique at a time, observe live, and classify outcomes
• Clean up artifacts and close gaps in-session
• Record structured results and end with a prioritized handoff

Next you will learn to measure coverage and close detection gaps with metrics that drive improvement.