How to Choose a CREST Penetration Testing Provider in the UK

Failing to properly vet and assess your penetration testing provider can leave your organisation dangerously exposed. While penetration testing is meant to identify and mitigate security gaps, ineffective engagements can create a false sense of security, leaving vulnerabilities untouched. Below are the most common challenges businesses face when engaging with the wrong provider:

1. Poor Scoping

One of the most significant oversights in penetration testing is incomplete scoping. If the provider does not fully understand or include all critical assets—such as remote endpoints, third-party integrations, or cloud environments—then the test results will be incomplete. Gaps in coverage mean that real threats can go undetected, and attackers will inevitably exploit them.

2. Inadequate Reporting

Even when vulnerabilities are discovered, if the findings are delivered in vague, overly technical, or poorly structured reports, they may be misunderstood or deprioritised by internal stakeholders. Effective reports should translate technical findings into business impact, include clear severity ratings, and provide step-by-step remediation advice that your teams can act on.

3. Lack of Follow-up or Support

A major red flag is when a provider offers no post-engagement support. Testing alone is not enough organisations often need help interpreting findings, applying patches, and verifying that fixes are effective. Without this follow-up, vulnerabilities may persist even after being flagged.

Real-World Example

In 2023, a UK-based SME conducted a penetration test with a low-cost provider. The test focused only on the company’s on-premises systems, neglecting their cloud-based storage and collaboration tools. Just two months later, attackers exploited misconfigured cloud assets to deploy ransomware across the organisation. The breach led to days of downtime, permanent data loss, and regulatory scrutiny under GDPR.

The Consequences of Inaction

Ignoring these common challenges can have severe consequences. Beyond just technical failures, organisations may face:

Data breaches and theft of intellectual property.
Financial losses from operational downtime or ransom payments.
Regulatory fines due to non-compliance.
Long-term reputational damage that erodes customer trust.

To avoid these pitfalls, businesses must conduct thorough due diligence when choosing a penetration testing provider. Confirm that they conduct comprehensive scoping, deliver actionable reporting, and provide post-test support. A strong provider helps you move beyond vulnerability discovery to measurable risk reduction.

If you’re not asking the right questions or working with the right team you’re not testing effectively. You’re just getting a report.

To effectively mitigate cybersecurity risks, businesses should adopt a strategic and comprehensive approach to penetration testing. Start by clearly defining the scope of the test. This means identifying and including all critical assets endpoints, networks, applications, and cloud infrastructure to avoid blind spots.

Next, ensure your testing provider holds CREST accreditation, verifying their credentials on the official CREST UK website. This guarantees they meet recognised industry standards for technical expertise and ethical testing.

It's also vital to review the methodologies the provider uses. Confirm they follow established frameworks such as NIST, OWASP, or Cyber Essentials, which promote consistency, transparency, and thoroughness in the testing process.

Before signing off, request a sample report to assess its clarity and usefulness. An effective report should categorise findings by severity, offer actionable remediation guidance, and be understandable to both technical and non-technical stakeholders.

Finally, don’t overlook post-test support. Choose a provider that offers follow-up consultation or retesting to validate that issues have been resolved.

At Cybergen, we recommend a layered approach: combining scheduled penetration testing with ongoing employee cybersecurity training and robust endpoint protection. This integrated strategy significantly improves an organisation's ability to detect, respond to, and recover from cyber threats.

Choosing the right CREST-aligned cybersecurity partner is critical to the success of your security testing strategy. The partner you select should demonstrate not only technical capability but also a deep understanding of your industry’s unique risks and compliance landscape.

Start by evaluating their experience and sector specialisation. A partner familiar with your business vertical be it finance, healthcare, government, or education will better understand the threat landscape and regulatory pressures you face. This insight enables more focused, relevant testing.

Next, assess their accreditations and certifications. CREST membership is essential, but a well-rounded partner should also hold recognised standards such as ISO/IEC 27001 for information security management, and Cyber Essentials Plus for practical, baseline protection. These certifications reinforce a commitment to best practices and continual improvement.

A strong CREST-aligned partner will reject a one-size-fits-all mentality. Instead, they should offer a customised approach to penetration testing. Every business environment is different, and testing should be tailored to your infrastructure, risk profile, and business priorities.

Equally important is communication. Look for a partner who provides clear, jargon-free reporting and delivers briefings suitable for both technical teams and business stakeholders. This ensures everyone understands the risk—and the necessary response.

At Cybergen, we believe that transparency and collaboration are key to effective penetration testing. Our approach is to align each engagement with your specific business model, ensuring vulnerabilities are not only discovered but contextualised. We go beyond testing we partner with you to strengthen your organisation’s overall cyber resilience.

Before selecting a penetration testing provider, it’s essential to vet their experience, credibility, and approach. The right questions can help you uncover their strengths, weaknesses, and alignment with your organisation’s security needs.

Start by verifying their CREST registration. Ask:

“What is your CREST registration ID?”

This ensures they are a recognised and trusted provider operating under strict ethical and technical standards.

Next, request transparency by asking:

“Can you share a sample redacted report?”

A well-structured sample will give insight into how findings are presented, whether they include severity ratings, technical depth, and clear remediation steps. Look for reports that translate technical issues into business risks.

Operational impact matters. Ask:

“How do you ensure minimal disruption during testing?”

Professional providers should follow coordinated procedures, schedule tests during low-traffic periods, and maintain constant communication to avoid downtime or performance issues.

Also inquire about aftercare:

“What support do you provide after the engagement?”

The best providers offer post-assessment briefings, retesting, and guidance to ensure your vulnerabilities are addressed and resolved effectively.

Finally, think long-term:

“How frequently should we conduct tests?”

This will help you understand the provider’s philosophy on continuous improvement and risk management. Depending on your environment, regular testing (quarterly or biannually) may be necessary.

These questions not only assess technical competence but also reveal how well the provider communicates and partners with clients. A high-quality testing firm won’t just uncover vulnerabilities they’ll empower your team to understand and fix them.

Asking the right questions is the first step toward securing the right partner and protecting your organisation from ever-evolving threats.

Selecting a penetration testing provider requires more than checking technical capabilities it demands vigilance for warning signs that could indicate inexperience, poor quality, or questionable ethics. Here are key red flags to watch for:

1. Inability to Prove CREST Membership

A credible provider should readily provide their CREST registration ID or a link to their listing on the official CREST website. If they cannot produce this, it raises serious concerns about the validity of their credentials and whether they follow recognised standards of practice and conduct.

2. Lack of Methodology Transparency

Professional penetration testers follow structured and recognised frameworks such as OWASP, NIST, or OSSTMM. If a provider refuses to share their testing methodology, it may signal a lack of maturity or a one-size-fits-all approach both of which can leave your systems exposed.

3. Generic, Low-Value Reports

Reports that are vague, copy-pasted, or lack detail show that the provider isn't investing time in understanding your environment. Quality reports should include asset-specific findings, clear severity ratings, and actionable remediation guidance tailored to your infrastructure.

4. No Post-Test Support or Remediation Help

Security testing is only half the equation what follows is equally critical. Be wary of providers who offer no assistance in interpreting results or supporting remediation. A responsible provider will walk you through findings, answer questions, and even offer validation testing post-fix.

5. High-Pressure Sales Tactics

Any vendor who pushes for immediate contracts, especially without a thorough consultation or scoping discussion, should raise alarm bells. Cybersecurity is about partnership and trust, not aggressive upselling.

These red flags often indicate a lack of professionalism, experience, or ethical standards, and engaging the wrong provider can do more harm than good. In some cases, poorly conducted tests could even disrupt operations or leave you with a false sense of security.

Protect your organisation by conducting proper due diligence: verify credentials, request references, ask for sample reports, and insist on a transparent process. Your cybersecurity posture depends on it.

Cybergen is a UK-based, CREST-approved penetration testing company dedicated to helping organisations strengthen their cybersecurity posture with clarity and confidence. As trusted security partners, we provide a comprehensive range of services tailored to meet the evolving needs of modern businesses.

Our offerings include thorough penetration testing across multiple environments—internal networks, external-facing systems, web applications, and cloud infrastructure. Each engagement is scoped with precision, executed with industry-recognised methodologies, and concluded with clear, actionable reporting.

We also support organisations in achieving Cyber Essentials Plus certification, guiding you through compliance requirements and technical controls to ensure readiness and resilience.

Beyond testing, we invest in your long-term security success through custom training programs designed for in-house IT teams. These sessions focus on vulnerability management, secure configurations, and how to respond to real-world threats.

For organisations seeking continuous assurance, Cybergen offers ongoing monitoring and testing support, enabling proactive detection and remediation of emerging vulnerabilities.

Our mission is simple but critical: to empower organisations with the tools, insight, and support they need to defend against cyber threats confidently and effectively.