Red Teams try to break things. Blue Teams try to stop them.

That sounds like a perfect relationship until both teams finish an exercise, write separate reports, move on, and discover six months later that the same detection gap still exists.

Purple Teaming exists to make that interaction more useful.

Instead of treating offensive and defensive security as isolated activities, Purple Teaming puts both sides in the same feedback loop: execute an attack technique, observe what defenders can see, identify what failed, improve the control, and test it again.

The goal is not proving who won.

It is making the organization harder to attack the next time.

What Is Purple Teaming?

Purple Teaming is a collaborative security practice where offensive and defensive teams work together to validate and improve security controls.

If Red and Blue Teams are still unfamiliar concepts, our article on Red Team vs. Blue Team explains their individual roles in more detail.

In simple terms:

• Red Team: simulates attacker behavior.
• Blue Team: detects, investigates, and responds to that behavior.
• Purple Teaming: makes both sides share what they learn and improve the defenses together.

A Purple Team does not always need to be a permanent third department. It can be a temporary collaborative exercise where offensive and defensive specialists work toward the same objective. Microsoft describes its own purple-team exercises as joint operations built around real-time information sharing between ethical hackers and defenders. Microsoft Learn

How Purple Teaming Works

A Purple Team exercise should start with a specific security behavior to validate.

For example, the Red Team may execute a technique associated with credential access, persistence, or lateral movement.

The process might look like:

Attack technique → Observe telemetry → Check detection → Find gap → Improve control → Retest

The important part is the feedback loop.

If the Red Team performs an action and the Blue Team detects it immediately, the organization has evidence that the control works.

If the activity appears in telemetry but generates no useful alert, the Detection Engineering process can improve the rule.

If the activity is not visible at all, the problem may be telemetry rather than detection logic.

This is where Purple Teaming becomes more useful than simply asking whether an attack “worked.”

Purple Teaming vs. Traditional Red Teaming

Traditional Red Team exercises often prioritize realism.

The offensive team may attempt to remain hidden, chain multiple techniques together and simulate how a real adversary would operate. The Blue Team may not know when or how the exercise will happen.

That is useful because it tests the defensive organization under realistic conditions.

Purple Teaming has a different objective.

Instead of maximizing stealth, both teams can deliberately test individual behaviors and immediately discuss what happened.

A traditional Red Team assessment may answer:

Can an attacker achieve this objective?

Purple Teaming adds another question:

If they try, can we actually see and stop them?

One does not replace the other. They test different things.

Where Detection Engineering Fits

Purple Teaming and Detection Engineering fit naturally together.

In our article on Detection Engineering, we discussed how telemetry becomes useful security signals through hypotheses, detection logic, testing, and tuning.

Purple Teaming provides a controlled way to validate those detections against real attacker behavior:

Threat behavior → Telemetry → Detection rule → Validation → Tuning → Retest

Frameworks such as MITRE ATT&CK are particularly useful here because they provide a shared language for describing adversary techniques. MITRE specifically documents ATT&CK as a resource for adversary emulation, Red Teaming, and threat-based Purple Teaming. MITRE ATT&CK

That shared language makes it easier to say exactly what behavior was tested and which defensive capability should have detected it.

What Good Purple Teaming Looks Like

Effective Purple Teaming needs more than putting Red and Blue Team members in the same meeting.

Each exercise should have a clear objective, defined techniques, available telemetry, and an expected defensive outcome.

The results should answer practical questions:

Was the behavior visible? Did a detection fire? Did it provide enough context? Could analysts investigate it? Did the defensive control actually stop anything?

Most importantly, improvements should be tested again.

Execute → Observe → Improve → Retest → Validate

Without the retest, the team only knows that someone changed something.

It does not know whether the change actually worked.

Conclusion

Purple Teaming turns offensive testing into a defensive improvement cycle.

The Red Team demonstrates what an attacker can do. The Blue Team shows what the organization can see and respond to. Purple Teaming connects those two perspectives and converts gaps into measurable improvements.

Because discovering that your detection failed is useful.

Discovering the exact same thing during the next exercise because nobody retested it is mostly just tradition.