Services Penetration Testing Services in the UK
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Penetration Testing Services in the UK

Penetration testing simulates real-world adversarial activity against your networks, applications, cloud environments, and APIs, identifying exploitable weaknesses before genuine attackers do. It is a core requirement under PCI DSS, ISO 27001, SOC 2, and Cyber Essentials Plus, and an essential discipline for any organisation handling sensitive data.

RedSecLabs delivers CREST-certified penetration testing across the full UK estate of testing disciplines: external infrastructure, internal network, web applications, APIs, mobile applications, cloud platforms, wireless networks, and bespoke red team engagements.

Our testers are senior offensive security practitioners holding OSCP, CREST CRT/CCT, OSCE, and equivalent certifications, not generalists running automated tools and calling the output a penetration test.

CREST Certified Pen Test Provider ISO Certified OSCP Certified Industry Certification

Free Security Quote

Just a few questions to scope your project. We respond the same business day.

✓ UK-based CREST member · ✓ QSA-aligned methodology · ✓ Same-day scoping response · ✓ Executive + technical reports · ✓ Retest included
CREST
Certified company
OSCP
Lead testers minimum
5 disciplines
Network, web, mobile, cloud, API
48h
Initial scoping turnaround

What is penetration testing?

Penetration testing is the discipline of simulating adversarial activity against specific systems to identify exploitable vulnerabilities. Unlike vulnerability assessment (which is broad and largely automated), penetration testing is narrow and largely manual, a skilled tester thinking like an attacker, chaining individual weaknesses into meaningful attack paths.

Different test types cover different attack surfaces: external infrastructure tests perimeter exposure; internal network tests post-breach lateral movement; web and mobile application tests identify business-logic and OWASP Top 10 weaknesses; cloud tests assess IAM and configuration weaknesses; API tests examine programmatic interfaces in increasing demand from modern applications.

What our penetration testing delivers:

Identification of exploitable vulnerabilities before attackers find them

Evidence satisfying PCI DSS, ISO 27001, SOC 2, Cyber Essentials Plus

Detailed remediation guidance for every finding

Executive risk narrative suitable for board reporting

Validation of defensive controls in realistic conditions

Reduced attack surface and improved detection capability

Penetration testing is a snapshot, high-quality but point-in-time. Most clients combine annual pentests with continuous vulnerability assessment for compounding security improvement.

Why penetration testing matters

Vulnerability scanners find known vulnerabilities. Penetration testers find what scanners miss, business logic flaws, authentication bypasses, privilege escalation paths, chained vulnerabilities that individually look minor but together enable serious compromise. These are the vulnerabilities that real attackers exploit.

Penetration testing is also mandated or strongly expected under every major compliance framework: PCI DSS Requirements 11.4.1-11.4.5, ISO 27001 Annex A.12.6.1, SOC 2 CC7.1, Cyber Essentials Plus. The quality of the test directly impacts the credibility of your compliance posture.

Without quality penetration testing, organisations face:

Undetected business-logic and authentication weaknesses

Exploitable attack chains that scanners cannot find

Compliance failures across PCI DSS and ISO 27001

Successful breaches via vulnerabilities a tester would have caught

Wasted budget on low-quality tests producing scanner-style output

Reduced board confidence in security programme effectiveness

A high-quality penetration test repays its cost many times over in identified critical weaknesses, validated controls, and demonstrated security programme maturity.

Who needs penetration testing?

Penetration testing is essential for any organisation handling sensitive data or operating internet-facing services. RedSecLabs delivers testing across:

Financial services and fintech

E-commerce and retail (PCI DSS)

SaaS and B2B technology

Healthcare and HealthTech

Defence and MoD supply chain

Cloud-native organisations

Professional services and law firms

AI and ML platforms

If you handle customer data, accept payments, or operate critical-path systems, you need professional penetration testing, at minimum annually, more frequently for high-risk environments.

Our Penetration Testing Methodology

A CREST-aligned methodology combining recognised industry frameworks (OWASP, NIST SP 800-115, OSSTMM) with adversarial creativity drawn from years of red-team experience.

01

Scoping & Rules of Engagement

We agree the testing scope, in-scope and out-of-scope targets, rules of engagement, escalation contacts, and testing window, all documented before any activity starts.

02

Reconnaissance & Enumeration

OSINT gathering, asset discovery, port and service enumeration, and technology fingerprinting to understand the target environment as an attacker would.

03

Vulnerability Identification

Combination of automated scanning and manual investigation to identify potential weaknesses across the in-scope estate.

04

Exploitation & Validation

Manual exploitation of identified weaknesses to confirm impact, demonstrate business-logic flaws, and chain individual issues into meaningful attack paths.

05

Privilege Escalation & Lateral Movement

Where in scope, demonstration of post-compromise activity, privilege escalation, lateral movement, data access, to assess realistic blast radius.

06

Reporting & Findings Review

Detailed report with executive summary, technical findings, exploitation evidence, and prioritised remediation guidance, reviewed live with your team.

07

Remediation Support

We support your team through remediation of identified issues, answering questions and providing guidance as fixes are implemented.

08

Retest & Validation

Optional retest of remediated findings to validate fixes, included in scope for most engagements.

Typical engagement lengths: external infrastructure 3-5 days, web application 5-10 days, internal network 5-10 days, mobile application 5-10 days, complex environments 10-20+ days.

What you receive

Every penetration test engagement with RedSecLabs includes:

  • Scoping document and signed rules of engagement
  • Executive summary for board and management consumption
  • Detailed technical findings with exploitation evidence
  • CVSS-rated severity and exploitability prioritisation
  • Practical remediation guidance for every finding
  • Walk-through review session with your technical team
  • Retest of remediated findings within engagement
  • Compliance-ready attestation for PCI DSS, ISO 27001, SOC 2

Industries We Serve

We deliver this service across these industries:

Financial Services
Healthcare
SaaS & Technology
E-commerce & Retail
Defence & Government
Cloud & Managed Services
Education
Professional Services

Why RedSecLabs for penetration testing

Penetration testing is a skill-led discipline, and the gap between a tester running automated tools and a senior offensive security practitioner finding chained business-logic flaws is enormous. We staff every engagement with senior, certified testers, deliver reports that drive remediation rather than confuse it, and include retesting in scope so you actually fix what we find.

CREST-certified company and senior OSCP testers
Manual testing, not automated scan output
Reports that drive remediation, not confusion
Retest included in scope
Compliance-ready evidence for PCI, ISO, SOC 2
Engagement starts within 1-2 weeks

Schedule Your Penetration Test

Book a free 30-minute scoping call. Fixed-fee proposal within 48 hours, engagement starts within 1-2 weeks.

Book a Scoping Call Contact Us

Where to next

Related services and industry packages worth exploring.

CREST Penetration Testing

Red Team Assessment

Adversary-simulation when standard pentest is not enough

Vulnerability Assessment
Related reading

From the RedSecLabs research blog

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Penetration Testing vs Vulnerability Assessment

When you need a pentest vs a vulnerability scan.

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Penetration Testing Costs: Detailed Guide

What drives pentest pricing and how to scope sensibly.

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From the blog

Evaluating a CREST Pentest Provider

How to choose a CREST-accredited tester beyond just the badge.

Read on the RedSecLabs blog

Frequently Asked Questions

External infrastructure, internal network, web application, API, mobile application (iOS and Android), cloud platform (AWS, Azure, GCP), wireless network, social engineering, physical, and bespoke red team engagements. Each engagement is scoped to the specific assets and threat scenarios that matter to you.

Typical engagements: external infrastructure 3-5 days; web application 5-10 days; internal network 5-10 days; mobile application 5-10 days; complex multi-target engagements 15-25 days. We scope honestly, a test that's too short will miss important findings.

All lead testers hold OSCP at minimum; senior staff hold OSCE, CREST CRT or CCT, GIAC GPEN/GXPN, and equivalent certifications. We staff engagements with the right seniority for the target, complex web applications and red teams get our most experienced practitioners.

Most testing is non-disruptive, careful enumeration, manual exploitation of confirmed vulnerabilities, controlled validation. We discuss any potentially disruptive activity in advance and obtain explicit approval. For high-availability environments we can test against production-equivalent environments or schedule sensitive testing during agreed maintenance windows.

Yes, retest of remediated findings is included in scope for most engagements. We re-validate critical and high findings after your team has implemented fixes, providing updated reporting that reflects the post-remediation state. This is critical for compliance evidence under PCI DSS and ISO 27001.

External infrastructure tests £4,000-£10,000; web application tests £6,000-£18,000; internal network tests £8,000-£20,000; complex multi-target engagements £20,000-£60,000+. Pricing reflects tester days, not licence fees. Fixed-fee quotes provided within 48 hours of scoping.
Before you decide
Download a sample report →
A redacted RedSecLabs penetration test report. See the format, depth, and clarity your team will receive.
Talk to us
Book a scoping call →
A 30-minute call covers realistic effort, timeline, and a fixed-scope quote. CREST-aligned methodology, UK-based testers.
What you receive

Every engagement includes

  • ✓ Scoping call. A 30-minute call to define scope, timeline, and authorisation boundaries.
  • ✓ Test plan. Written test plan covering targets, methodology, and rules of engagement.
  • ✓ Technical report. Detailed findings with reproduction steps, evidence, and remediation guidance.
  • ✓ Executive summary. Board-ready summary with risk ratings and business impact.
  • ✓ Audit-ready evidence. Findings letter formatted for auditors, customers, and supervisory authorities.
  • ✓ Retest letter. Free retest of remediated findings within agreed window. Confirmation letter included.
  • ✓ Remediation call. A call with our lead tester to walk through findings and remediation strategy.
How we deliver

Our process, end to end

  1. 1
    Scoping call & fixed-scope quote
    A 30-minute call. We define scope, targets, timeline. You get a fixed-scope quote within one working day.
  2. 2
    Test plan & authorisation
    Written test plan covering methodology, targets, and rules of engagement.
  3. 3
    CREST-aligned execution
    Senior tester runs the engagement. Critical findings flagged immediately during testing.
  4. 4
    Technical + executive report
    Detailed technical findings with reproduction steps. Board-ready executive summary.
  5. 5
    Remediation call & retest
    Walkthrough with our lead tester. Retest of remediated findings within the agreed window.
Engagement scope

What shapes the quote

Small scope
Focused scope, smaller surface. 5-7 working days.
Medium scope
Multi-role, several integrations. 8-12 working days.
Enterprise scope
Complex environment, compliance evidence. 12-25 working days.
Fixed-scope quote within 1 working day
No surprise invoices. We commit to a number before you commit to us.
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