What is Purple Team?

Traditional red team engagements are adversarial by design: the red team attacks without warning the blue team, and success is measured by how far they get and how long they stay undetected before a final report is delivered weeks later. That model tests the organization's overall readiness, but it produces a lag between finding a gap and closing it, and a lot of the red team's tradecraft (the specific commands, the exact registry keys touched, the process lineage) gets lost in translation between the technical attacker and the analyst who has to build a detection from a summary paragraph.

Purple teaming restructures the exercise around a shared MITRE ATT&CK technique list instead of a black-box objective. A typical session picks a set of techniques, say T1078 (valid accounts), T1055 (process injection), and T1021 (remote services), and works through them one at a time with both teams in the same room or call. The red team executes the technique live and narrates exactly what they're doing at the command level. The blue team watches their SIEM, XDR, and firewall consoles in parallel to see whether anything fired, and if nothing did, the two teams immediately diagnose why, missing log source, an overly narrow correlation rule, a detection that exists but wasn't tuned for this specific variant, and write or adjust the detection before repeating the technique to confirm it now fires.

This produces two concrete artifacts a standard red team engagement doesn't: a technique-by-technique coverage map showing exactly which ATT&CK techniques the blue team can detect today, and a set of newly validated detection rules built and confirmed working during the same session rather than added to a backlog. Purple team exercises are typically shorter and more frequent than full red team engagements, sometimes run monthly or quarterly against a rotating slice of the ATT&CK matrix rather than as a single large annual test, which keeps detection coverage current as adversary techniques and the organization's own environment both change over time.