Penetration Testing London
CREST-certified penetration testing services for London businesses. We find the vulnerabilities attackers exploit — before they do.
EJN Labs provides penetration testing services to businesses across London, the South East, and the whole of the UK. As a CREST-certified penetration testing company, our engineers hold the highest industry accreditations — and we work to the same standards whether you’re a start-up in Shoreditch or a financial institution in Canary Wharf.
London businesses face a distinct threat landscape: concentration of high-value financial data, complex hybrid cloud environments, regulatory pressure from the FCA, ICO, and sector regulators, and a sophisticated threat actor community that specifically targets UK financial services, legal, and technology firms. Our penetration testing methodology is built around those realities.
Penetration Testing Services in London
Our London clients commission penetration testing for a range of reasons: FCA/PRA compliance, SOC 2 or ISO 27001 audit requirements, pre-acquisition technical due diligence, and proactive security assurance. We cover the full range of penetration testing engagements:
Why London Businesses Choose EJN Labs
There are hundreds of penetration testing companies in London. Here’s what distinguishes CREST-certified providers — and why it matters for your business:
CREST-Certified Engineers
CREST (Council of Registered Ethical Security Testers) certification means every engineer on your engagement has passed rigorous technical examinations in their discipline. It’s the standard required by NCSC, many financial regulators, and increasingly mandated in procurement frameworks across the UK public sector. You can verify our accreditation directly at crest-approved.org.
UK-Based Team, Not Offshore Delivery
All work is performed by our in-house UK team. No subcontracting, no offshore delivery centres. This matters for data sovereignty, NDA enforceability, and the practical ability to have a discovery call at a reasonable hour. For London-based engagements requiring on-site elements (physical penetration testing, on-premises network testing), our engineers can be on-site within the M25 the next business day.
Findings Delivered as You Go, Not 4 Weeks Later
Traditional penetration testing means waiting four weeks for a PDF report after the testing window closes. By then, the context is stale and the development sprint that could have fixed the vulnerabilities has already shipped. We deliver findings to your team as they’re discovered, through our client portal. Critical issues can be remediated before the engagement even ends.
FCA and Regulatory-Ready Reports
Our reports are structured to satisfy FCA, ICO, PCI DSS, ISO 27001, and SOC 2 audit requirements. If your auditor or regulator has specific reporting requirements, we’ll align the deliverable to their format before the engagement begins — not as an afterthought.
Penetration Testing Companies London: How to Choose
When evaluating penetration testing companies in London, the key questions to ask are:
- Is the company CREST-approved? Check at crest-approved.org — not just the individual tester’s certification, but the company-level accreditation. This verifies insurance, professional standards, and quality controls.
- Do the engineers hold individual CREST certifications? Company accreditation and individual certification are separate. Ask which specific certifications the engineers assigned to your engagement hold.
- Is your data handled in the UK? For regulated firms, data sovereignty matters. Confirm that all findings, credentials, and test data remain within UK infrastructure.
- What’s included in the scoping process? A credible penetration testing company will invest time in scoping before quoting. Flat-rate quotes without a scoping call often mean inadequate testing depth.
- How are findings delivered? Ask to see a sample report. Good reports provide CVSS scores, reproduction steps, screenshots, and remediation guidance — not just a list of CVE identifiers.
Penetration Testing Services London: Our Process
Every engagement follows a consistent methodology aligned to CREST standards, PTES (Penetration Testing Execution Standard), and OWASP where applicable.
| Phase | What Happens | Your Involvement |
|---|---|---|
| 1. Scoping | We define the target scope, testing approach (black/grey/white box), rules of engagement, and timeline | 30-60 min call + scope document review |
| 2. Intelligence Gathering | OSINT and reconnaissance on target systems, exposed services, technology stack | Minimal — we work independently |
| 3. Active Testing | Manual exploitation attempts, automated tool-assisted discovery, business logic testing | Technical contact available for queries |
| 4. Reporting (live) | Findings delivered to portal as discovered; critical issues flagged immediately | Monitor portal; remediate critical findings |
| 5. Final Report | Executive summary + full technical report with CVSS scores and remediation guidance | Review and submit to auditors/regulators |
| 6. Retest (optional) | Verify remediation of original findings at agreed point | Provide remediation evidence |
Who We Work With in London
Our London client base spans a range of sectors where security assurance is non-negotiable:
- Financial services — Banks, payment processors, fintechs, and insurance firms requiring FCA-aligned testing and PCI DSS compliance
- Legal and professional services — Law firms and consultancies handling privileged client data with specific confidentiality requirements
- Technology and SaaS — London-based product companies needing web application and API penetration testing for SOC 2 and ISO 27001
- Healthcare and life sciences — Organisations handling patient data under UK GDPR with NHS supply chain requirements
- Retail and e-commerce — Businesses processing card payments under PCI DSS scope
- Critical national infrastructure — Utilities, transport, and public sector organisations with NCSC guidance requirements
Frequently Asked Questions
How long does penetration testing in London take?
Most engagements run 3–10 days of active testing, depending on scope. A web application test for a mid-size application typically takes 5 days. Infrastructure tests for a 200-node network take 5–7 days. We provide a timeline estimate at the end of the scoping call.
Do you offer on-site penetration testing in London?
Yes. For internal network penetration tests and physical security assessments, we can deploy engineers to your London offices. We’re based in the UK, so same-day or next-day on-site availability is standard.
How much does penetration testing cost in London?
Pricing depends on scope, complexity, and testing type. Web application tests typically start from £2,500–£4,500 for a standard application. Infrastructure tests start from £3,500. See our pricing page for indicative ranges, or request a scoping call for a firm quote.
Can you provide penetration testing for FCA-regulated firms?
Yes — a significant portion of our London client base are FCA-regulated. Our reports are structured to satisfy FCA SYSC requirements, and we carry professional indemnity insurance appropriate for regulated client engagements.
Are your engineers CREST-certified?
Yes. EJN Labs is a CREST-approved company, and our engineers hold individual CREST certifications relevant to their testing discipline. You can verify our company accreditation at crest-approved.org.
Get a Free Scoping Call
Tell us what you need to test, and we’ll tell you exactly what it involves and what it costs. No sales pitch — a 30-minute technical scoping call with one of our engineers.
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