Purple Team: When It Beats a Red Team

A red team is adversarial and quiet. A purple team is collaborative and loud. The techniques overlap almost entirely; the posture is opposite.

In a purple team exercise the attackers and defenders work in the same room, or the same call. The attacker runs a technique and says so. The defenders look for it. If they cannot see it, everyone stops, works out why, fixes the gap, and runs it again.

The output is not a report about whether you were caught. It is a list of techniques you can now detect and could not that morning.

Why it is usually the better first purchase

A red team answers one question — would we notice this? — with one attempt at one route. If the answer is no, you learn that one thing, expensively.

A purple team answers it across dozens of techniques in the same time, and fixes each gap as it appears. When detection coverage is genuinely unknown, which it is for most organisations, that is a far better trade.

The sequence that usually makes sense:

1. Penetration testing, until hygiene findings stop dominating.
2. Purple teaming, to build and verify detection coverage.
3. Red teaming, to test whether that coverage holds against someone patient who is not announcing themselves.

Buying the third before the second usually produces an expensive demonstration of something a cheaper exercise would have shown.

What an exercise looks like

Techniques are usually selected against a public framework so coverage is measurable rather than anecdotal — commonly MITRE ATT&CK, which catalogues adversary behaviour by tactic.

For each technique: the attacker runs it, the defenders check their tooling, and the result is recorded as detected, logged but not alerted, or invisible. The middle category is the interesting one — the data was there and nothing drew attention to it, which is a tuning problem rather than a coverage problem and is usually fixable the same day.

Where a gap is found, it is fixed and the technique re-run. That loop is the whole point.

What you get

A coverage matrix: techniques down one axis, your detection outcome across the other. Run it again in six months and the difference is the measurement.

This is considerably more useful to a security team than a narrative about one successful intrusion, and considerably less useful to a board, which is worth knowing when deciding who the report is for.

When a red team is genuinely the right answer

• Detection coverage is already measured and believed to be good, and the question is whether it survives someone patient.
• Response — not detection — is being tested: whether alerts get acted on at two in the morning.
• Something outside technical controls is in question: people, premises, suppliers.
• An external requirement names an adversarial exercise specifically.

The full comparison with penetration testing is in red team versus penetration testing.