Purple Team Operations: A Practical Guide

To understand purple teaming, it helps to understand what it improves upon.

The traditional teams

The red team emulates adversaries — attacking systems, evading defenses, and demonstrating impact. The blue team defends — monitoring, detecting, and responding to threats. In a classic engagement, these teams operate in opposition and often in secrecy: the red team tries to achieve objectives without being caught, and the blue team is tested on whether it notices.

The limits of the adversarial model

This model is valuable for validating defenses under realistic conditions, but it has a weakness: learning is slow and incomplete. When the red team succeeds by evading detection, the blue team learns only that it missed something — not precisely what, or how to catch it next time. Findings arrive in a report weeks later, detached from the moment they could have taught the most.

The purple alternative

Purple teaming keeps the realism of adversary emulation but removes the secrecy. Red and blue work side by side: the red team executes a technique, and both teams watch to see whether — and how — the defense detects it.

This transforms testing from a scored contest into a collaborative training and tuning exercise. When a technique goes undetected, the teams fix the gap immediately, then re-run the technique to confirm the fix works. The result is faster, deeper improvement than either team achieves alone. GuardsArm runs purple team exercises specifically to accelerate this learning loop for clients' security operations.

Purple teaming is best understood as a mode of collaboration that can be adopted whether or not an organization has dedicated red and blue staff.

Two ways to run it

• Dedicated teams collaborating. Organizations with distinct red and blue functions bring them together for joint exercises, sharing information openly rather than competing.
• A blended function. Smaller organizations may not have separate teams; here, testers and defenders (often the same people, or an external partner and internal staff) work through attack techniques together.

Transparency as the defining trait

What makes an exercise "purple" is not the roster but the transparency. The red team announces what it is about to do; the blue team watches their tooling to see whether it fires. There is no hiding and no scoring of who won. The shared objective is understanding and improving detection.

Roles in an exercise

A typical exercise involves an operator executing techniques, defenders monitoring detection tooling, and a facilitator keeping the exercise focused on objectives and capturing outcomes. Clear documentation of what was executed and what was observed is essential.

The single cultural prerequisite is that missing a detection is treated as a discovery to celebrate and fix, never a failure to hide. Blame kills the feedback loop that makes purple teaming work.

GuardsArm often serves as the offensive operator and facilitator in a purple exercise, working alongside the client's defensive team to identify and close detection gaps collaboratively.

Purple teaming requires red and blue to speak the same language about attacker behavior. MITRE ATT&CK is that language, and it is central to modern purple team operations.

A common taxonomy

ATT&CK is a knowledge base of adversary tactics, techniques, and procedures observed in real intrusions. Tactics describe attacker goals (initial access, persistence, privilege escalation, lateral movement, exfiltration); techniques describe specific ways of achieving them. Because both teams reference the same framework, there is no ambiguity about what was tested or what was detected.

Planning exercises around techniques

Exercises are typically planned as a set of ATT&CK techniques to execute. This makes scope concrete and coverage measurable: for each technique, the question is simply whether the defense prevented, detected, or missed it. Threat intelligence can guide selection — emulating the specific techniques used by adversaries known to target the organization's sector produces the most relevant results.

Building a coverage map

Mapping exercise results onto the ATT&CK matrix produces a detection coverage map — a visual, honest picture of which adversary behaviors the organization can catch and which it cannot. Over time, this map becomes a strategic tool for prioritizing detection investment.

ATT&CK turns a vague question — "are we secure?" — into a precise, answerable one: "which of these specific attacker techniques can we detect, and how quickly?"

GuardsArm structures purple exercises around ATT&CK so that results translate directly into a measurable coverage picture the client can track over time.

The heart of purple teaming is a tight iterative loop executed for each technique in scope. It is what distinguishes purple teaming from a report delivered after the fact.

The loop

• Execute. The operator runs a specific technique against the environment, announcing it so defenders know what to look for.
• Observe. Defenders watch their SIEM, EDR, and other tooling to see whether an alert fires, what telemetry is generated, and how clearly the activity stands out.
• Analyze the gap. If nothing fires — or the signal is buried — the teams investigate why. Is the telemetry missing? Is the log source not collected? Is a detection rule absent or mis-tuned?
• Tune. The blue team writes or adjusts a detection rule, enables a missing log source, or improves an alert.
• Retest. The operator re-runs the technique to confirm the new detection fires reliably and does not drown the analyst in false positives.

Why real-time beats reporting

The magic of purple teaming is immediacy. A detection gap identified and closed in the same session — then verified — is worth far more than the same gap listed in a report weeks later, disconnected from the context that would make it fixable.

Documentation as you go

Each technique's outcome — detected or not, telemetry available, detection created — is recorded during the exercise. This running log becomes the exercise report and the basis for tracking improvement. GuardsArm facilitates this loop so that each technique tested leaves behind a concrete improvement rather than merely a finding.

A purple team exercise that improves detections only for the duration of the session has failed. The lasting value comes from detection engineering — codifying and maintaining the detections the exercise produces.

From ad hoc rule to durable detection

A detection tuned live during an exercise must be hardened into something reliable and maintainable. This means writing it clearly, documenting the technique it addresses and the telemetry it depends on, testing it against both true and false positives, and version-controlling it.

Detection-as-code

Leading teams manage detections like software — detection-as-code. Rules live in version control, are peer-reviewed, and are tested through a pipeline before deployment. This brings rigor, repeatability, and history to detection content, and it prevents the silent decay that afflicts hand-managed rules.

Guard against alert fatigue

A detection that fires constantly on benign activity is worse than no detection — it trains analysts to ignore alerts. Every new detection must be tuned for a signal-to-noise ratio the SOC can actually sustain.

Retesting during the exercise is the first check on false positives; ongoing tuning keeps detections useful as the environment evolves.

Mapping and gap closure

Each detection should be mapped to the ATT&CK technique it covers, feeding the coverage map and revealing where gaps remain. Over successive exercises, the organization builds a growing, documented library of tested detections tied to real adversary behaviors. GuardsArm helps clients translate exercise outcomes into durable, well-engineered detections rather than temporary fixes that fade after the testers leave.

Purple teaming is a program, not a one-off event, and it needs metrics that reflect its true purpose: improving detection and response.

Measure improvement, not "wins"

The wrong question is "did the red team get in?" The right questions are: which techniques can we now detect that we could not before, how quickly do we detect them, and how fast can we respond?

Meaningful metrics include detection coverage across the relevant ATT&CK techniques, the number of new detections created and validated per exercise, and improvements in mean time to detect and respond.

Track coverage over time

The ATT&CK coverage map, updated after each exercise, shows the trajectory of the program. A steadily filling map is direct evidence that defensive capability is growing — exactly the kind of progress leadership can understand and fund.

Sustain the cadence

Purple teaming delivers the most value when run regularly, not once. Environments change, new techniques emerge, and detections decay. A recurring cadence — with each exercise informed by current threat intelligence — keeps detection capability aligned with the real threat landscape.

Build the culture

The lasting benefit of purple teaming is often cultural: red and blue stop seeing each other as adversaries and start operating as one team with a shared mission. That collaboration outlasts any single exercise. GuardsArm partners with organizations to establish a sustained purple team cadence, measure detection improvement, and build the collaborative culture that makes defensive capability compound over time.