Why Purple Teaming

Purple teaming is a collaborative security practice where offensive (red) and defensive (blue) functions work together in the same loop instead of in isolation.

The goal is not to 'win' against each other, but to jointly improve detection and response. The red side emulates real adversary behavior; the blue side validates whether they can see and stop it; both refine controls together.

• Red brings attacker tradecraft and emulation
• Blue brings telemetry, detections, and response
• Purple is the feedback loop between them

Traditional red team engagements often end with a report that lands months later. The blue team learns what was missed only after the fact, with little context on the exact technique or telemetry involved.

This creates slow, expensive feedback. A finding like Domain admin compromised in 3 days tells you that you lost, but not which detection should have fired.

• Red findings arrive late and lack detection detail
• Blue cannot reproduce the attack to tune rules
• The same gaps reappear in the next engagement

Purple teaming compresses the cycle from months to hours. Red executes a technique, blue immediately checks the SIEM/EDR, and the team decides on the spot whether coverage exists.

A typical micro-loop looks like this:

• Red runs one ATT&CK technique in a controlled window
• Blue queries telemetry for the expected artifact
• If nothing fires, a detection gap is logged then and there
• A new rule is drafted and re-tested in the same session

This execute-observe-improve rhythm is the heart of purple teaming.

Purple teaming distinguishes clearly between prevention (the attack is blocked) and detection (the attack is allowed but visible and alerted).

For each technique tested you classify the outcome:

• Blocked — control stopped the action (e.g. AppLocker, AV)
• Detected (alerted) — telemetry generated an alert
• Logged (no alert) — evidence exists but nothing fired
• No telemetry — total blind spot

The worst outcome is 'no telemetry', because you cannot build a detection on data you never collect.

Effective purple teaming is driven by threat intelligence. Instead of testing arbitrary tools, you emulate the techniques used by adversaries that actually target your sector.

For example, a financial institution might emulate the TTPs associated with FIN7 or a known ransomware affiliate, mapping each step to ATT&CK.

• Pick a threat actor relevant to your industry
• Build an emulation plan from documented TTPs
• Test the techniques you are most likely to face

This keeps testing realistic and prioritizes the detections that matter most.

A purple team exercise needs clear roles so the session stays productive:

• Red operator — executes techniques and narrates each action
• Blue analyst — drives the SIEM/EDR and confirms visibility
• Detection engineer — writes or tunes rules in real time
• Facilitator/scribe — keeps to the plan and records results

Transparency is key: unlike a covert red team test, here red announces what it is doing so blue can correlate it precisely with the telemetry.

Several free frameworks make purple teaming repeatable. They let red execute consistent, documented techniques that blue can verify.

• Atomic Red Team — small, ATT&CK-mapped test cases
• MITRE Caldera — automated adversary emulation
• VECTR — tracking assessment results and coverage over time

A single Atomic test is invoked with its technique ID, for example:

Even though both sides cooperate, purple teaming touches production systems and must be run responsibly and ethically.

• Get written authorization and define scope precisely
• Prefer a representative lab or staging environment first
• Have a rollback and cleanup plan for every technique
• Coordinate timing so on-call teams are not blindsided

Destructive techniques (ransomware encryption, data exfiltration of real data) should be simulated with harmless stand-ins, never run for real against production data.

Purple teaming turns vague confidence into measurable coverage. After each exercise you can express results as a percentage of techniques detected.

A simple coverage view per tactic might read:

• Initial Access: 4 of 6 techniques detected
• Execution: 5 of 5 detected
• Lateral Movement: 1 of 4 detected (gap)

Mapping this onto the ATT&CK matrix as a heatmap makes blind spots visible to leadership and guides where to invest next.

The biggest value of purple teaming comes from running it continuously. Detections decay as environments change, logging breaks, and adversaries evolve.

• Re-test previously closed gaps to catch regressions
• Add new techniques as fresh threat intel arrives
• Track coverage trends quarter over quarter

Some teams automate this as continuous validation, where emulation runs on a schedule and alerts the team when a known detection stops firing.

Beyond technical metrics, purple teaming improves the relationship between offense and defense. Analysts learn attacker tradecraft; operators learn what telemetry their actions generate.

• Blue gains hands-on understanding of real TTPs
• Red learns which behaviors are noisy versus stealthy
• Both build shared language around ATT&CK

This shared understanding is often the most durable outcome: it persists long after any single exercise report is archived.

Test your understanding of the core purpose of purple teaming.

You now understand why purple teaming exists and what it delivers:

• It bridges red and blue into one execute-observe-improve loop
• It classifies outcomes as blocked, detected, logged, or blind spot
• It is driven by threat-informed adversary emulation mapped to ATT&CK
• Tools like Atomic Red Team, Caldera, and VECTR make it repeatable
• It must run ethically with authorization, scope, and cleanup plans
• Its value compounds when run continuously to catch detection decay

Next, you will learn how to map specific attacks to detections using the MITRE ATT&CK framework.