Cyber resilience testing: pen testing, red teaming, or both?

Stop asking 'pen test or red team?' and start asking 'what evidence do we need?' A practical guide to building a repeatable cyber resilience testing programme.

If you've ever sat in a security planning meeting and heard someone ask 'so, do we do a pen test or a red team exercise?', you'll know the question usually stalls into a long debate about cost and scope rather than a clear answer. The problem isn't the options available, it's the framing. Choosing a test methodology before deciding what you need to prove is a bit like choosing between an X-ray and an MRI before anyone's described the symptom.

The better question is: what evidence does your organisation need to demonstrate cyber resilience? Once you answer that, the methods follow naturally.

Start with the evidence, not the method

Cyber resilience testing isn't one thing. It's a set of activities that, together, should answer four distinct questions your stakeholders, auditors, and customers are actually asking:

• Can attackers get in? (prevention and exploitability)
• Do we detect fast enough? (detection gaps and SOC performance)
• Do we contain? (response and containment effectiveness)
• Can we restore? (recovery readiness)

A penetration test is well-suited to the first question. Red teaming and adversary emulation address the second and third. Continuous validation methods like Breach and Attack Simulation (BAS), Adversarial Exposure Validation (AEV), and ongoing scanning answer the fourth by keeping your controls honest between major exercises.

None of these is a replacement for the others. They're layers.

What penetration testing is actually for

A penetration test is a scoped, time-boxed exercise where testers attempt to exploit vulnerabilities within a defined environment. For SaaS and tech teams, that typically covers web applications, APIs, cloud configurations, network boundaries, and identity flows.

The deliverable you should expect isn't just a list of vulnerabilities. It's evidence of exploitability: proof that a specific flaw can be chained into a meaningful attack path, with clear remediation guidance and a priority order. That output directly feeds your control improvement plan and, critically, provides the technical evidence your auditors want to see for SOC 2 compliance or ISO 27001 certification.

Where penetration testing has limits: it measures your exposure, but it doesn't measure your response. If your logging is disabled, your SIEM missed the attack, or your on-call team took six hours to acknowledge the alert, a pen test won't tell you that.

What red teaming adds

Red teaming (or adversary emulation) is goal-driven. Rather than 'find all the bugs in this scope', the brief is 'reach the crown jewels without being caught'. The team maps their approach to real-world tactics, techniques, and procedures (TTPs), typically using MITRE ATT&CK as the shared language.

MITRE ATT&CK describes itself as a "common language and framework" that red teams use to emulate specific threats and plan operations. MITRE also publishes Adversary Emulation Plans that map specific threat actor reports to ATT&CK tactics and techniques, useful if you want your exercise to reflect the actual threat actors targeting your sector.

The output of a red team exercise isn't a vulnerability list. It's a picture of your defensive performance under realistic pressure: which attack paths succeeded, where detection failed, how long the team moved undetected (dwell time), and which controls held. That's integrating assurance and cybersecurity in the most practical sense.

For organisations subject to DORA's Threat-Led Penetration Testing (TLPT) requirements, or operating in regulated European financial environments, the frameworks TIBER-EU and CBEST are the relevant schemes. The European Central Bank describes TIBER-EU as "a European framework for threat intelligence-based ethical red-teaming". CBEST, implemented by the Bank of England, follows a similar threat intelligence-led assessment model. Both emphasise controlled, intelligence-driven exercises rather than open-ended hacking.

You can read more about DORA's specific requirements in our DORA compliance services overview.

Rules of engagement: the non-negotiable first step

Before any test, pen test, red team, or otherwise, you need a Rules of Engagement (RoE) document. NIST defines rules of engagement as "detailed guidelines and constraints regarding the execution of information security testing." In practice, this means a written agreement that covers:

• Scope and in-scope assets (what can be tested, what can't)
• Prohibited actions (e.g., no social engineering of named individuals, no denial-of-service)
• Testing windows (hours, blackout dates, change freeze periods)
• Stop conditions (see below)
• Comms plan (who gets notified, via which channel, and when)
• Incident separation (how to distinguish test activity from a real attack)
• Data handling (what data testers may touch and how it's protected)
• Legal and regulatory boundaries (relevant for NIS2-scoped entities or DORA-regulated firms)

Stop conditions deserve particular attention. Your RoE should specify that testing halts immediately if: the exercise creates a genuine availability risk to production systems; live business operations are materially impacted; a critical zero-day is discovered that requires immediate disclosure; or the comms channel between tester and client is lost. These aren't edge cases, they're the difference between a controlled exercise and an incident.

Skipping the RoE because 'it's just an internal test' is a mistake. Internal red teams need the same boundaries. Without documented stop conditions and scope, you're one misconfigured test script away from a self-inflicted outage.

A decision framework based on your maturity

Here's a simple way to choose:

The maturity gate matters too. If your logging and alerting are still immature, a full red team exercise will produce depressing results without the context to fix them. Start with targeted penetration tests and use the findings to baseline your controls. Once your SOC or SIEM is operating consistently, red and purple team exercises become far more instructive.

For most SaaS and tech teams, the right answer is do both: frequent exposure validation (pen tests plus monthly scans) combined with periodic adversary emulation (once or twice a year). That combination answers all four stakeholder questions. Securance's cyber security offering covers exactly this blend: penetration testing, monthly scans, code reviews and red teaming, all within a single programme rather than one-off engagements.

The KPIs that actually matter

A test is only useful if it produces metrics you can act on. The reporting structure that works best for security leaders has three layers:

1. Executive summary, risk and business impact, not just CVE scores
2. Technical appendix, evidence, TTP mapping (ATT&CK technique IDs), and exploitability proof
3. Remediation roadmap, named owners, due dates, and re-validation milestones

The KPIs worth tracking across your programme:

• Dwell time (how long did the simulated attacker move undetected?)
• Time to detect (when did the first alert fire?)
• Time to acknowledge (how long before a human picked it up?)
• Containment effectiveness (was lateral movement stopped, or did it succeed?)
• Number of high-risk exploitable paths proved (exploitability count, not just vulnerability count)
• Remediation lead time (average days from finding to fix)
• Validation pass rate (percentage of prior findings confirmed as remediated on re-test)

That last one is underused. Knowing that 85% of your last pen test findings were properly remediated, verified by re-test, is genuinely meaningful evidence for an auditor or a customer security questionnaire. It's also the kind of output that maps cleanly onto the cybersecurity risk assessment controls your frameworks require.

Where BAS and continuous testing fit

Breach and Attack Simulation (BAS) and Adversarial Exposure Validation (AEV) platforms sit in the continuous validation layer. They run automated attack scenarios against your controls, typically mapped to MITRE ATT&CK techniques, and tell you whether your detection and prevention tools would stop them.

They're not a replacement for manual testing. A BAS tool won't find a logic flaw in your API authentication or chain together novel privilege escalation paths the way a skilled human tester will. But they're excellent at keeping your detections current, validating that recent configuration changes haven't broken something, and scaling validation without scheduling a full red team every month.

Continuous Threat Exposure Management (CTEM) takes this further by integrating discovery, scoping, validation, mobilisation, and reporting into an ongoing cycle. For teams already running regular pen tests and red team exercises, CTEM provides the connective tissue between engagements.

A 90-day testing roadmap

If you're building a programme from scratch (or restarting one), this is a workable sequence for a SaaS/tech team:

Weeks 1–3: Prepare

• Finalise asset inventory, IAM documentation, and environment map
• Agree RoE with your testing partner (scope, stop conditions, comms plan)
• Establish baseline logging and alerting metrics (before the test, not after)
• Identify SOC escalation contacts and change windows

Weeks 4–8: Exposure validation

• Run a scoped penetration test across web apps, APIs, and cloud config
• Run automated scans and, if applicable, code review on critical components
• Document exploitability evidence and prioritise remediation by business impact

Weeks 9–12: Adversary emulation and learning

• Run one red team scenario targeting a realistic crown-jewels objective
• Hold a purple team workshop: blue and red teams review the attack timeline together, identify detection gaps, and validate fixes in near-real-time
• Produce the three-layer report (executive, technical, remediation roadmap)
• Schedule re-validation of critical findings within 30 days of remediation

This structure produces the vulnerability detection evidence, detection and response metrics, and remediation audit trail that standards like ISO 27001, SOC 2, NIS2, and DORA all look for, without running three separate disconnected programmes.

FAQ

Which is cheaper: pen testing or red teaming? Pen tests are generally scoped more tightly, which keeps costs lower. Red team exercises require more planning, longer engagement windows, and threat intelligence inputs, so they typically cost more. The real driver is what you need to prove, if you need exploitability evidence, a pen test is the efficient choice. If you need to measure defensive performance, you can't substitute a pen test for a red team.

Do we need RoE even for internal teams? Yes. Internal red teams need documented scope, stop conditions, and a comms plan just as much as external providers. The risk of unintended production impact doesn't change because the tester has a company email address.

How often should we run each? For most SaaS/tech teams: penetration tests at least annually (and after major releases or infrastructure changes), monthly automated scans continuously, red team exercises once or twice a year depending on regulatory requirements and maturity. One-time pen testing isn't enough to demonstrate ongoing resilience.

Will a pen test satisfy a resilience requirement? Partly. A pen test provides prevention and exploitability evidence, useful for ISO 27001, SOC 2, and similar frameworks. But resilience requirements (particularly under NIS2 and DORA) also ask about detection, response, and recovery. Those need additional testing methods beyond a standard pen test scope.

What if we don't have strong SIEM/EDR yet? Start with penetration testing to surface your highest-risk exposures and fix them. Use the findings to prioritise your detection investments. Once you have consistent logging and alerting, you'll get much more value from red and purple team exercises, and you'll have a baseline to measure detection improvement against.

Build a testing programme that produces real evidence

The question isn't 'pen test or red team?' It's 'what do our stakeholders, auditors, and customers need us to prove about our security posture, and how do we build a repeatable programme that produces that evidence?'

At Securance, we work with over 800 professional firms and SaaS companies across Europe to answer exactly that question. Our integrated Advisory, Assurance, and Cyber Security approach means your testing programme isn't isolated from your compliance posture, the evidence it generates feeds directly into your Single Audit, Multiple Standards workflow covering SOC 2, ISO 27001, ISAE 3402, NIS2, and DORA through one streamlined process.

If you'd like to talk through your objectives, current maturity, and the right blend of testing methods for your environment, we'd be glad to help you build the programme, not just book the test.