Red Teaming vs. Penetration Testing: Why Both Matter for Cyber Security

Cyber security conversations often begin with a straightforward question: How secure are we?

For many organisations, the answer starts with a penetration test. It's familiar, widely required for compliance, and produces a clear report outlining technical weaknesses. But in today’s threat environment, exposure is only part of the picture. What ultimately matters is whether your organisation can detect and respond effectively once an adversary begins moving inside your environment.

That distinction is where red teaming becomes critical.

Although penetration testing and red teaming are frequently discussed together, they serve different purposes. Both are important. Both add value. But they test very different aspects of your security posture. Understanding how they complement each other is essential if your goal is resilience rather than compliance alone.

In simple terms

Before going deeper, here is the practical distinction:

• • Penetration testing identifies exploitable technical vulnerabilities within defined systems or applications.
  • Red teaming simulates realistic adversary behaviour to test detection, response, and organisational resilience.
  • Purple teaming aligns offensive and defensive teams to improve those capabilities collaboratively.

Each plays a role in a mature security program. The key is knowing when and why to use them.

What penetration testing actually proves

Penetration testing focuses on uncovering weaknesses in networks, applications, cloud environments, and infrastructure. It simulates attack techniques within a defined scope to determine whether vulnerabilities can be exploited.

A well-executed penetration test may reveal:

• • Misconfigurations
  • Unpatched software
  • Weak authentication controls
  • Exposed services
  • Application flaws

It provides clarity and highlights technical risk. It supports regulatory obligations and demonstrates due diligence. For many organisations, it is a necessary and responsible step.

However, penetration testing is typically time-bound and tightly scoped. It shows where weaknesses exist, but it does not fully test how your organisation would detect and respond if an attacker were actively attempting to achieve specific objectives over time.

That limitation is not a weakness in the method. It simply reflects its purpose.

What red teaming is designed to test

Red teaming takes a broader and more strategic approach.

Rather than concentrating on individual vulnerabilities, a red team simulates the behaviour of a real adversary operating inside your environment. The objective is not just to gain access, but to achieve meaningful goals aligned with what a genuine attacker might pursue.

Those goals may include:

• • Accessing sensitive data
  • Escalating privileges
  • Moving laterally across systems
  • Maintaining persistence
  • Avoiding detection

In many red team exercises, defensive teams are not informed of the specific timing or techniques being used. This allows the organisation to assess not only technical controls, but also monitoring visibility, alerting processes, escalation pathways, and incident response coordination.

Where penetration testing asks, “Can someone get in?”, red teaming asks, “Would we see it happening, and how effectively would we respond?”

Where purple teaming fits

Purple teaming builds on both approaches.

It brings offensive and defensive teams together in a collaborative model, allowing real-time feedback between attack simulation and detection improvement. Instead of operating independently, red and blue teams work together to refine detection rules, strengthen logging visibility, and improve response workflows.

For organisations operating a Security Operations Centre or Managed Detection and Response capability, purple teaming can provide structured validation that monitoring and response processes are functioning as intended.

It transforms testing from a periodic exercise into a continuous improvement mechanism.

The operational difference at a glance

To clarify the distinction:

Both approaches strengthen security. They simply measure different dimensions of risk.

Why this distinction matters now

Modern attackers do not rely solely on obvious exploits. They often abuse legitimate credentials, exploit identity weaknesses, and move laterally in ways that resemble normal operational behaviour.

At the same time, boards and regulators are asking more informed questions about cyber resilience. They expect assurance that controls are not only implemented, but effective. They want evidence of operational readiness, not just documentation.

In that environment, vulnerability discovery alone is not enough. Security maturity increasingly depends on validating exposure, detection capability, and response effectiveness as part of an ongoing cycle.

When to use each approach

Penetration testing is particularly valuable when you need to:

• • Identify technical vulnerabilities
  • Validate new systems before production
  • Support compliance and audit requirements
  • Assess specific applications or infrastructure components

Red teaming becomes especially relevant when your objective is to:

• • Test detection and monitoring capability
  • Evaluate incident response readiness
  • Simulate realistic adversary techniques
  • Identify gaps in operational resilience

Purple teaming is most effective when your goal is continuous improvement across offensive and defensive capabilities.

Mature security programs rarely choose one over the other. They implement each in the right context as part of a layered validation strategy.

From compliance to confidence

There is a meaningful difference between passing a test and being prepared.

Penetration testing helps you understand where technical weaknesses exist. Red teaming shows how those weaknesses could be exploited in practice and whether your organisation would detect and contain that activity. Purple teaming strengthens those capabilities through structured collaboration.

Together, these approaches move an organisation beyond compliance and towards operational confidence.

At The Missing Link, we work with organisations across regulated and high-growth sectors to design structured validation programmes that combine penetration testing, red teaming, and purple teaming. The objective is not simply to identify weaknesses, but to continuously strengthen detection capability and operational resilience over time.

If you are reviewing your security testing strategy and want to understand how it measures both exposure and resilience, we would welcome the conversation.
Get in touch with The Missing Link to discuss your security validation approach.