What Is Purple Team?

Purple teaming is the practice of offensive and defensive staff working together rather than in opposition — attacks executed openly, with defenders watching, so that both sides learn in the same session.

It emerged because traditional covert engagements, while valuable, produce a report weeks later and a limited amount of defensive improvement per unit of cost.

What it changes about testing

A red team engagement is covert and measures whether defenders detect something. A purple engagement is collaborative and measures why a technique was or was not detected, then fixes it while everyone is still in the room.

The feedback loop closes in minutes instead of weeks. A technique that goes unnoticed leads immediately to examining the telemetry, writing a detection and re-running the technique to confirm the alert fires.

How a session actually runs

A technique is selected, usually from MITRE ATT&CK. The offensive side executes it and says exactly what they did. The defensive side checks whether it was detected and what the telemetry shows.

If it was not detected, the gap is diagnosed on the spot: no telemetry, telemetry present but no rule, rule present but misconfigured. A detection is written, the technique is repeated, and the result is verified before moving on.

What it is better at

Detection engineering, unambiguously — it is the most efficient way to build verified coverage of specific techniques. Knowledge transfer, because defenders see attacks performed and understand what they look like in data.

And efficiency: one day of collaborative work frequently produces more verified detections than a longer covert engagement produces improvements.

What it does not replace

It does not test whether defenders would notice an unannounced intrusion, because nothing is unannounced. Realistic assessment of detection under genuine conditions still requires covert work.

Nor does it test the human and process dimensions a covert engagement exposes — escalation under uncertainty, decisions made without knowing whether something is real, communication when nobody has the full picture.

Prerequisites and cadence

It needs offensive capability, whether internal or bought in, and defenders with time and access to modify detection content. Without the second, techniques are demonstrated and nothing is fixed.

Regular short sessions work better than occasional long ones, because coverage accumulates and the working relationship between the two sides is itself part of the benefit.

Where the offensive capability comes from

Few organisations employ dedicated offensive staff, and the practice does not require them. A provider engaged for periodic sessions, or an internal engineer who has developed emulation skill using open tooling, both work — the requirement is someone who can execute techniques accurately and explain exactly what they did.

Automated emulation tooling covers part of this and runs repeatedly at low cost, which makes it useful for regression testing detections that were already built. It is weaker at the adaptation a person brings when a technique does not behave as expected.

Where to start

Run one session against five techniques relevant to your sector. The proportion that go undetected is usually surprising, and each one closed is verified coverage rather than an assumption.

See red team versus penetration test. GuardsArm runs penetration testing.