Red Team vs. Blue Team vs. Purple Team: Building a Unified Cyber Defence

Why your security strategy needs more than preventive controls

Most enterprises spend millions on firewalls, endpoint protection, and access controls, then discover their defences fail the moment a real attacker gets creative. The mistake that many companies make is assuming that static defences can handle dynamic threats.

Attackers don’t follow playbooks your security tools were designed to catch. They chain together small weaknesses (a misconfigured cloud bucket, a phished credential, an unpatched internal service) into full compromise paths that no single product would flag. Your security posture can look flawless on a compliance checklist and still crumble under pressure.

This is where adversarial testing changes the equation. Instead of waiting to find out whether your defences hold during an actual breach, you create controlled scenarios where skilled people try to break in, other skilled people try to stop them, and both sides learn from the outcome. That is the Red Team, Blue Team, and Purple Team model.

The shift from passive defence to this kind of proactive, continuous security testing is one of the most effective investments we’ve seen organisations make in cybersecurity maturity. Unfortunately, it is also the one that many delay because it feels expensive, disruptive, or hard to scope.

We’ll break down exactly what each team does, how they operate together, and how to measure whether the investment is paying off, so you can make the decision with clarity rather than guesswork.

The offence: what is a red team?

A Red Team’s job is to think and act like a real adversary. Not to run a vulnerability scanner and hand over a PDF. They conduct attack simulations with the creativity, persistence, and patience of an actual threat actor, using many of the same tactics, techniques, and procedures (TTPs) used in real-world attacks.

Their primary objective is to find the path of least resistance into your most valuable assets and prove it’s exploitable, before someone with worse intentions does the same.

Red Team operators start with reconnaissance, gathering intelligence about your organisation’s technology stack, employee roles, third-party vendors, and publicly exposed services. From there, they develop attack plans that might include:

The mindset matters as much as the methodology. A good Red Team doesn’t stop at the first vulnerability. They chain findings together, just like a real attacker would. They test whether your Blue Team detects them. They document how far they got, how long it took, and which controls failed.

One thing most people get wrong: conflating a penetration test with a Red Team engagement. A pentest is typically scoped, time-boxed, and focused on finding as many vulnerabilities as possible. A Red Team engagement simulates a specific threat scenario end-to-end, often with only a handful of senior leaders aware that it’s happening. The difference in realism and in what you learn is substantial.

The defence: What is a blue team?

Blue Teams are your standing defence. They operate every day, not just during exercises, monitoring systems, hunting for threats, and responding to incidents when they happen.

Their mandate covers detection, response, and mitigation. In practice, that means:

Blue Teams also own the organisation’s security playbooks and runbooks. These are the documented procedures for handling specific incident types: ransomware, credential theft, data exfiltration, and insider threats.

The friction point that often arises is that Blue Teams are often stretched thin. They manage alert fatigue from noisy detection tools, deal with false positives daily, and must prioritise which signals to investigate with limited staff. Without Red Team pressure to test their assumptions, blind spots persist. Detections that look solid on paper may fail against techniques they’ve never encountered in their environment.

The best Blue Teams share one trait: they treat every missed detection as a learning opportunity, not a failure. That mindset is what separates a reactive security operations centre from one that actually improves over time.

The collaboration: how purple teams bridge the gap

In most organisations, Purple Teaming is a collaborative function rather than a permanent standalone team. It is a structured approach that forces Red and Blue Teams to share information in real time rather than trading reports after the fact.

Without Purple Teaming, here’s what typically happens: the Red Team runs an engagement, writes a report listing what they exploited, and hands it to the Blue Team. The Blue Team reads it weeks later, disputes some findings, implements some fixes, and moves on. The learning is fragmented and slow. Critical context (how exactly the attack bypassed a specific detection rule, or why a particular technique went unnoticed for three days) gets lost.

Purple Team exercises fix this by putting attackers and defenders in the same room, sometimes literally, sometimes virtually. The Red Team executes a technique. The Blue Team checks whether they detected it. If they didn’t, both sides figure out why, right then. The Blue Team writes a new detection rule or adjusts a configuration. The Red Team tries again or moves to the next technique.

This feedback loop compresses weeks of back-and-forth into hours. It also builds something harder to measure but equally valuable: mutual respect and shared understanding between offence and defence. Red Teamers learn the constraints Blue Teams work under. Blue Teamers learn how attackers actually think, not how a textbook says they think.

The Purple Team operating model turns security exercises from periodic assessments into a continuous improvement cycle. That shift in mindset, from “test and report” to “test, learn, and adapt together,” is where the real security gains happen.

Operational playbooks: how each team works

Red team: tactics, techniques, and procedures

Red Teams structure their work around the MITRE ATT&CK framework, a public knowledge base that catalogues adversary behaviour across the attack lifecycle. It organises techniques into 14 tactical categories: Reconnaissance, Resource Development, Initial Access, Execution, Persistence, Privilege Escalation, Defence Evasion, Credential Access, Discovery, Lateral Movement, Collection, Command and Control, Exfiltration, and Impact.

A Red Team engagement might look like this:

Common tools include commercial adversary emulation platforms such as Cobalt Strike (for command-and-control) — used both by professional Red Teams and, increasingly, by real-world attackers — BloodHound (for Active Directory attack-path mapping), and Burp Suite (for web application testing), as well as custom scripts tailored to the target environment.

Blue team: the incident response lifecycle

Blue Teams follow established incident response frameworks. The two most common are NIST’s four-phase model (Preparation; Detection and Analysis; Containment, Eradication, and Recovery; Post-Incident Activity) and the SANS Institute’s six-phase PICERL model, which breaks the middle stages out into more granular steps:

Most Blue Teams blend the two — NIST’s phases for compliance reporting, SANS’s granularity for day-to-day operational playbooks.

The gap between preparation and real-world readiness is where most teams struggle. Your runbook might say “isolate the infected host,” but it doesn’t account for the fact that the infected host is a production database server serving 50,000 active users.

Purple team: structured collaboration

Purple Team exercises map Red Team techniques directly to Blue Team detection capabilities. A typical framework involves:

This process creates a validated detection coverage map: a clear picture of which attacker techniques you can catch and which ones you can’t. That map becomes one of your most valuable security artefacts.

Implementing a security exercise programme

The first decision is whether to build these capabilities in-house, outsource them, or use a hybrid approach. Each has trade-offs.

In-house teams

In-house teams offer deep organisational knowledge and availability for ongoing operations. But recruiting experienced Red Team operators is expensive and competitive. A senior offensive security consultant commands a high salary, and you need enough of them to cover diverse skill sets (network, application, cloud, social engineering).

Outsourced teams

Outsourced teams bring fresh perspectives and specialised expertise. External Red Teams won’t share the same assumptions as your internal team might. They’ve seen hundreds of environments and know which weaknesses recur. The downside: they lack institutional context and require onboarding time.

For most mid- to large-sized enterprises, we recommend a hybrid model. Maintain an internal Blue Team (since defence is a continuous operation) and bring in external Red Team specialists for periodic engagements. Purple Team exercises then become the integration point.

Planning the exercise

Three elements determine success or failure before anyone touches a keyboard:

Define objectives

“Find vulnerabilities” is not an objective. “Determine whether an attacker who compromises an employee’s email can reach the payment processing database within 48 hours” is an objective. Tie exercises to your actual risk concerns.

Scope the engagement

Decide which systems, networks, and locations are in bounds. Exclude anything where uncontrolled testing could cause real harm (production medical devices, safety-critical infrastructure). Document exclusions clearly.

Establish rules of engagement

Define escalation procedures, emergency contacts, and conditions under which the exercise pauses or stops. Determine who knows the exercise is happening (usually a small group of senior leaders, not the entire SOC, if you want realistic results).

Red team KPIs

Blue team KPIs

Purple team KPIs