What is purple teaming?

Key takeaways

• Purple teaming is collaboration, not a separate team. It is the structured way red (attack) and blue (defense) work together to improve detection during the engagement.
• The defining property: technique is shared in real time, so defenders build and tune detections while the attack is running, not from a report weeks later.
• It produces durable improvement in detection coverage faster than a black-box red team engagement followed by a report-driven remediation cycle.
• It works for organizations without a formal blue team, as long as there is someone responsible for telemetry and response.
• Purple teaming is most useful when the goal is to mature detection and response, not when the goal is to measure black-box detection performance.

How does a purple team engagement work?

A purple team engagement runs in tight loops. Each loop is a single attacker technique executed against the live environment, with the defender watching telemetry in real time, talking with the attacker, and tuning detection on the spot.

A typical loop:

1. Pick a technique. Usually mapped to a specific MITRE ATT&CK technique. Example: T1003.001 (LSASS Memory access) or T1566.001 (Phishing with attachment).

2. Execute. The attacker runs the technique against a designated host or user account. The defender knows it is happening; the goal is detection improvement, not surprise.

3. Observe. The defender watches what their stack reports: EDR alert, SIEM rule, email gateway log, IDS signature, anomaly score. Whether the technique fires an alert, fires a vague alert, gets logged but not alerted, or produces nothing at all.

4. Discuss. The attacker explains the technique: what they did exactly, what variants exist, what an attacker would do next. The defender explains what their stack saw, what got through, and why.

5. Build or tune detection. The defender writes or modifies a detection (a SIEM rule, an EDR custom indicator, a SOAR playbook step) to catch the technique cleanly. The attacker re-runs the technique to confirm the detection fires.

6. Document. Technique, detection, evidence, and validation are logged into the program backlog.

The engagement moves through dozens of these loops in a day. Coverage grows technique by technique against the ATT&CK matrix relevant to the organization's threat profile.

Red team vs blue team vs purple team

The three are roles, not always different teams. The distinction matters because the confusion is widespread.

• Red team. The attackers. In an external engagement, an outside provider; in mature internal programs, a dedicated in-house function. Goal: simulate adversary behavior to find weaknesses.
• Blue team. The defenders. Detection engineers, SOC analysts, incident responders, sysadmins responsible for the security posture of their systems. Goal: detect, contain, and recover from intrusions.
• Purple team. The collaboration model in which red and blue work together with attacker technique exposed during execution. Not a separate team; a way of working.

In the ARG model, purple teaming is the default operating mode during continuous engagements, with periodic no-knowledge red team work layered above it to test what the workforce has learned to detect. See What is adversarial simulation? for how these modes coexist.

Why purple teaming matters for small security teams

A mid-market manufacturer rarely has a dedicated red team. Often the blue team is one IT lead plus a managed detection and response (MDR) partner. Black-box red teaming against such an environment usually produces a report that says "very few of these techniques were detected", which is true but not actionable: the defending team did not have the capacity to build detections under fire and does not have the bandwidth to read a hundred-page report afterward.

Purple teaming changes the economics for small teams in three ways:

1. Detection improvement happens in the room. Every loop ends with a tuned detection. The team does not leave the engagement with a remediation backlog of unknown size; it leaves with a measurably improved detection stack.
2. The defender's capacity is the constraint, and it is respected. A purple team can run for two days, six days, or as a recurring half-day-per-quarter cadence depending on what the team can absorb. A black-box red team imposes a fixed delivery cost regardless of whether the team can act on it.
3. Tradecraft transfers. The defender finishes the engagement understanding what attackers actually do at the technique level, not just what to look for in a rulebook. That understanding compounds across future engagements and into the team's incident response practice.

For organizations whose security maturity is "we have EDR, we have a SIEM, we have MFA, we have an IT lead", purple teaming is often the highest-leverage engagement available.

Examples of purple team exercises

What ARG runs with a typical mid-market manufacturer's IT team:

• Phishing landing detection. Execute a credential-harvest landing page identical in structure to a real attacker's. Walk through what the email gateway saw, what the browser-side controls did, what the SIEM logged, and what would have alerted. Tune the detection. Re-run. See What is spear phishing?.
• LSASS access via a benign-looking process. Run a Mimikatz-equivalent through a process the EDR does not flag by default. Confirm whether the EDR raises the right alert, whether the SIEM correlates LSASS-access events with the user's context, and whether the response playbook is triggered.
• Lateral movement over SMB with valid credentials. Move from one host to another using legitimately stolen credentials. Walk through whether identity-anomaly detection catches the unusual logon, whether the destination host's telemetry tells the right story, and whether the SOC can reconstruct the chain.
• OAuth consent grant to a suspicious app. Walk a user through accepting an OAuth grant to a controlled test app with high scopes. Confirm whether the tenant's app governance policy alerts, whether the SIEM correlates the grant with the subsequent API activity, and whether the revocation workflow works end to end. See What is consent phishing (OAuth phishing)?.
• C2 traffic over DNS. Beacon out using DNS tunneling to a controlled sinkhole. Confirm whether the network telemetry catches the anomaly, whether the DNS firewall blocks the resolver, and whether the SIEM raises the right correlation.

Each loop adds one or more tuned detections to the stack. Over a multi-day engagement, detection coverage measurably improves against the ATT&CK techniques most relevant to the organization.

What deliverables come out of a purple team engagement

A purple team engagement is operational, not narrative. The deliverables reflect that:

1. Detection inventory delta. A list of detections built, tuned, or deprecated during the engagement, with the underlying ATT&CK techniques each covers.
2. Coverage map. A view of the ATT&CK matrix annotated with what is now detected, what is alert-only, what is log-only, and what is not visible. Compared to the pre-engagement state.
3. Playbook updates. Changes to incident response playbooks based on what worked and what did not during execution. See What is an incident response plan (IRP)?.
4. Operational evidence. Screenshots, log queries, rule code, and SOAR playbook diffs. The artifacts the defending team will reference and re-use.
5. Backlog. Techniques the engagement did not get to, ordered for the next session.

The deliverable is not a report. It is a measurable improvement to the production detection stack, with documentation sufficient for the defending team to maintain it.

Best practices for purple team collaboration

For an engagement to produce real improvement:

1. Pick the ATT&CK techniques in scope before the engagement. Twenty to forty per day is realistic. Open-ended exploration produces less than focused coverage.
2. Have the defender drive the loop, not the attacker. The defender's stack and time budget are the constraint. The attacker adjusts pace to the defender's ability to tune.
3. Use a real environment, not a lab. Detection coverage built in a lab does not transfer. Real production telemetry is the point.
4. Build detections that survive false positives. A detection that fires on the technique and also on benign workflow gets disabled in two weeks. Plan a false-positive review during the engagement.
5. Document every detection in the team's own terms. Rule code, ATT&CK mapping, false-positive tolerance, expected response. If the rule's owner cannot maintain it, the rule will rot.
6. Test the response, not just the alert. A detection that fires and goes unread is not improvement. Walk through the response playbook for each new detection.
7. End each session with a backlog and a calendar entry. The next session has a defined scope and a defined date. Purple teaming compounds when it is recurring.

Purple teaming FAQs

Do I need a blue team to do purple teaming?

You need someone responsible for detection and response, but it does not need to be a dedicated blue team. A small IT team, a managed detection and response (MDR) partner, or even a single security-aware sysadmin can be the defending side in a purple team exercise, as long as they have access to the relevant telemetry and the authority to act on findings.

Is purple teaming a one-time exercise or ongoing?

Both. A purple team can be a single multi-day exercise focused on a specific scenario, or it can be a recurring rhythm where attack technique and defender response are exercised continuously. The recurring model produces more durable improvement; the one-time model produces a faster initial uplift.

Can purple teaming be done remotely?

Yes. Most of the work happens over screen-share and chat: attackers execute, defenders watch telemetry, both narrate what they see. In-person sessions help for the first engagement to build trust between teams, but ongoing cadence works well remotely.

How does purple teaming improve incident response?

Purple teaming exercises the detection-to-response path in real time. The defending team sees a real attack technique, tunes the detection, and walks through the response with the attacker present to explain what they were doing and what they would do next. The result is faster, more accurate alerting and a response team that has actually practiced the playbook against live adversary behavior. See What is incident response (IR)?.

How ARG facilitates purple teaming for lean manufacturing IT teams

Most ARG clients are mid-market manufacturers with one or two people responsible for security alongside their other IT duties. A black-box red team against such a team produces a report nobody can act on. Purple teaming respects the constraint and produces operational improvement.

ARG runs purple teaming as part of the continuous engagement model, in two forms.

Recurring quarterly sessions. Half-day to one-day sessions, run remotely, focused on a defined set of ATT&CK techniques relevant to the client's threat profile (ransomware affiliate TTPs, BEC operator TTPs, vendor-impersonation chains). Output: tuned detections deployed before the session ends.

On-site escalation during physical engagements. During the on-site engagement weeks (What is a physical security audit?), the operating team runs paired sessions with the client's IT lead, walking through both the physical and digital findings as they happen. The IT lead leaves the engagement having actually built detections for the techniques the operators just used.

James Wall leads the digital-side technique work; David Ashby leads the physical and on-site facilitation. The client team is the defender. The deliverable is an improved production stack, a recurring cadence, and a documented detection inventory the client owns.

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