A purple team is a collaborative security testing practice in which offensive specialists (the red team) and defensive specialists (the blue team) work side by side in the same exercise to execute attack techniques, observe whether they are detected and improve defenses immediately. The term describes a way of working more often than a permanent department: red and blue combined give purple.
In security testing, the purple team approach answers a specific question that penetration testing and red teaming often leave open: can our defenders actually see and stop this technique, and if not, what exactly must change? The output is not a list of vulnerabilities but a set of validated, tuned detections and response procedures.
How a purple team exercise works
A purple team exercise follows a transparent test, observe and improve cycle. Unlike a covert red team engagement, the defenders know what will be executed and when, because the goal is learning and measurement rather than proving that a breach is possible.
- Select techniques based on threat intelligence, usually expressed as MITRE ATT&CK technique IDs relevant to the organization.
- Agree on expectations: which log source, rule or alert should fire for each technique.
- Execute the technique in a controlled way, often one step at a time.
- Observe the result together: logged, alerted, blocked or invisible.
- Fix and retest: write or tune the detection, then run the technique again until it is caught.
- Document the outcome, the change made and any remaining gaps.
Each technique is therefore tested at least twice, before and after the fix. This closed feedback loop is the defining feature of the purple team method and the reason it produces measurable improvement within days rather than months.
Roles must be clear before the first technique runs. A facilitator keeps the schedule and records outcomes, the operator executes techniques, and defenders search their tools in real time. A shared tracking sheet, keyed by technique ID, prevents the common situation in which results are remembered differently by each side afterward.
Red team, blue team and purple team compared
The three colors describe different goals and levels of transparency, not different skill sets. The same people may take part in all three activities during a year.
| Approach | Main goal | Defender awareness | Typical output |
|---|---|---|---|
| Red team | Emulate a real adversary end to end | Usually unaware | Narrative of attack path and impact |
| Blue team | Detect, respond and harden | Not applicable | Alerts, incidents, hardening changes |
| Purple team | Validate and improve detection together | Fully aware | Tuned detections, coverage map |
| Penetration test | Find exploitable weaknesses in scope | Often aware | Vulnerability report with severity |
A covert red team engagement tests the whole organization under realistic pressure, including people and escalation. A purple team exercise trades that realism for depth and repeatability on specific techniques. Mature programs use both: red teams reveal what matters, purple teams fix it systematically.
Formats and tooling
Purple teaming ranges from a one-day workshop to a continuous program. The format depends on how mature the security operations center is and how much automation is available.
| Format | Duration | Best suited for |
|---|---|---|
| Workshop exercise | One to five days | First baseline of detection coverage |
| Adversary emulation plan | One to three weeks | Replaying a specific threat actor’s behavior |
| Continuous program | Ongoing, weekly or monthly cycles | Mature SOCs with detection engineers |
| Automated validation | Scheduled, unattended | Regression testing of existing detections |
Typical tooling includes adversary emulation frameworks such as Atomic Red Team, MITRE Caldera or Metasploit for technique execution, plus the defender’s SIEM and EDR for observation. Breach and attack simulation platforms automate part of the cycle, but they cannot replace the joint discussion in which analysts learn why a detection failed.
Measuring results
The value of a purple team is shown by coverage and detection metrics, not by the number of successful attacks. Each tested technique is assigned an outcome category, which allows progress to be tracked between exercises.
| Outcome | Meaning | Typical follow-up |
|---|---|---|
| Prevented | A control blocked the technique | Confirm alerting also exists |
| Alerted | An alert reached the analyst queue | Check severity and context |
| Logged only | Telemetry exists, no alert fired | Write a detection rule |
| Not observed | No relevant telemetry recorded | Add a log source or sensor |
Useful summary metrics are the share of tested techniques that alert, the time from execution to alert, and the number of detections added or improved per exercise. Results should be retested later, because changes in software, log pipelines or rule sets can silently break detections that once worked.
Metrics should be read with care. A rising alert share may simply reflect easier techniques chosen in the latest round, so programs compare results on a stable, versioned test set and report changes in that set separately.
Pitfalls and good practice
The most common failure is a purple team that produces a report but no changes. If detection engineers are not present or lack time to implement fixes, the exercise becomes an expensive demonstration.
- Prioritize by threat: test techniques used by adversaries relevant to the sector, not the whole framework at once.
- Test behavior, not tools: a detection that only matches one tool’s file name is easily evaded.
- Avoid blame: the exercise measures controls, not individual analysts.
- Control safety: run destructive techniques only in agreed scope, with rollback plans.
- Keep a living coverage map so results guide future investment.
Another pitfall is overfitting detections to the exact commands used in the exercise. Good practice is to vary the procedure, for example by changing parameters or using a different tool for the same technique, before declaring a gap closed.
In everyday language
A purple team is like a sparring session between a burglar and a security guard who are on the same side. The burglar tries one way of getting in, the guard watches the cameras and says whether the attempt was noticed. If it was missed, they adjust the alarm together and try again.
Instead of keeping the attack secret, both sides share everything so that every weak spot found is fixed on the spot. The result is a building, or a company network, that is measurably better at spotting real intruders.
Seen in the real world
A mid-sized insurance company learns from threat intelligence that ransomware groups targeting its sector often steal credentials from memory and move laterally with remote administration tools. It schedules a three-day purple team exercise with an external red team specialist and its own SOC analysts and detection engineer.
Of 24 selected techniques, the first run shows that 9 are alerted, 8 are logged only and 7 are not observed at all. During the exercise the team enables additional endpoint logging, writes 11 new detection rules and retests each technique. At the end, 19 of 24 techniques raise an alert, and the remaining gaps are documented with a plan for a missing sensor on legacy servers. Three months later an automated rerun confirms that the new detections still fire.