Penetration Testing
Services
Penetration testing is a controlled, manual security assessment where CREST-accredited ethical hackers simulate real-world attacks against your networks, applications, cloud infrastructure, and people to identify exploitable vulnerabilities before criminals do. Precursor Security delivers penetration testing services from £2,500 with fixed pricing and DBS-checked UK engineers, covering network, web application, API, and cloud testing.
Manual penetration testing by a CREST accredited company. We identify exploitable vulnerabilities across your networks, applications, and cloud infrastructure and show you exactly what an attacker would do with them. Used by financial services firms, NHS supply chain organisations, and UK legal practices to satisfy insurers, auditors, and enterprise customer requirements.
What is
penetration testing?
Pick the surface you need tested. Most UK engagements start with either network (your infrastructure: external perimeter, internal LAN, Active Directory) or web application (your live apps and APIs).
Network penetration testing is manual testing of your infrastructure by CREST-accredited engineers. The test you need depends on where the attacker starts.
External Network Pen Test
The attacker is on the internet
Internal Network Pen Test
The attacker is already inside
Web app pen testing manually exploits your live application as an unauthenticated visitor, then a standard user, then an admin. Aligned to OWASP Top 10, ASVS, and WSTG.
Price manipulation, workflow skipping, IDOR on critical objects
Horizontal and vertical privilege escalation, forced browsing
BOLA, mass assignment, broken object-level authorisation
JWT manipulation, OAuth flow abuse, MFA bypass, password reset
SQLi, XSS, SSRF, deserialisation, file upload, input handling
Outdated libraries, dependency confusion, exposed admin endpoints
We identify exploitable vulnerabilities before real attackers do.
Penetration testing is a simulated cyber attack conducted by certified ethical hackers to find and exploit weaknesses in your networks, applications, and infrastructure. New to this? Our guide explains what penetration testing is and how it works. Every finding is validated by a human, mapped to business risk, and delivered with production-ready remediation. For organisations that need more than an annual test, we also offer penetration testing as a service (PTaaS).
Book a Free Scoping CallPen Testing Services We Deliver
Our pen testing services cover the full attack surface, from internal and external network infrastructure to web applications, APIs, mobile platforms, and cloud environments. Each engagement is scoped individually, priced on a fixed-fee basis, and delivered by CREST-accredited testers. Read our guide to CREST penetration testing for the certification levels and when it is required.
View all testing typesWeb Application Penetration Testing
IDOR, SSRF, business logic flaws, authentication bypass, and OWASP Top 10 across your full application surface.
External Network Penetration Testing
Simulate an external attacker targeting your internet-facing perimeter, DNS, and public infrastructure.
Internal Network Penetration Testing
Active Directory attacks, lateral movement, privilege escalation, and segmentation validation from inside your network.
API Security Testing
Authentication flows, rate limiting, broken object-level authorisation, and unlinked endpoint discovery.
Mobile Application Penetration Testing
iOS and Android testing covering data storage, traffic interception, and platform-specific attack vectors.
Cloud Penetration Testing
IAM exploitation, storage bypass, container escape, and serverless abuse across AWS, Azure, GCP, and Microsoft 365.
Wireless Network Penetration Testing
WPA2 cracking, evil twin attacks, rogue access point detection, and wireless network segmentation review.
AI and LLM Penetration Testing
Prompt injection, insecure tool calling, RAG data leakage and guardrail bypass across LLM applications and AI agents.
NCSC IT Health Check
Formal ITHC testing for public sector organisations and PSN-connected environments, delivered to NCSC standards.
Human Logic.
Machine Speed.
Context Aware.
Scanners find “holes”. We find “rules” to break.
True Impact.
We understand that businesses don't just patch vulnerabilities, they reduce risk. We demonstrate the true business consequences of every finding.
Validated Risk.
If it's in the report, it's exploitable.
Production-Ready.
Tailored remediation advice to help engineering teams fix gaps fast.
Close gaps weeks faster.
Forget the static report. Watch findings appear in real-time on our secure platform, chat directly with engineers, and request instant retests.
Engineer Chat
Direct technical access
Instant Retests
Verify fixes on-demand
Flexible Formats
CSV, JSON, PDF
MITRE Mapped
Strategic context
Engagement Workflow
Structured to minimise operational friction and maximise the value of the testing window.
Scope
Day 1-2: Scoping call, threat model, and rules of engagement. Fixed-price quote confirmed before work begins.
Execute
Day 3-10: Manual exploitation, logic flaw discovery, and attack chaining by CREST-accredited testers.
Report
Within 5 working days of test completion: actionable findings mapped to true business risk.
Aftercare
30-day retest window included. Direct engineer access via our portal to verify remediation.
Scope
Day 1-2: Scoping call, threat model, and rules of engagement. Fixed-price quote confirmed before work begins.
Execute
Day 3-10: Manual exploitation, logic flaw discovery, and attack chaining by CREST-accredited testers.
Report
Within 5 working days of test completion: actionable findings mapped to true business risk.
Aftercare
30-day retest window included. Direct engineer access via our portal to verify remediation.
Penetration Testing
Pricing
Penetration testing cost in the UK ranges from £2,500 for a targeted external assessment to £15,000+ for complex multi-environment engagements. Every Precursor engagement is fixed-price, quoted after a free scoping call, with no hidden day rates. For a full breakdown by test type and worked examples, see our penetration testing cost guide.
All prices are fixed-quote after a free scoping call. No hidden day rates. Prices shown are guide starting points.
Scope & Delivery
Choose the testing model that matches your threat scenario, and understand the business case for proactive security investment.
Black Box Testing
External Attacker SimulationZero knowledge simulation. We seek to breach your perimeter without credentials, operating exactly like a blind, real-world adversary.
Grey Box Testing
RecommendedAuthenticated testing. We identify exactly what a compromised employee, malicious insider, or hijacked customer account could access and exploit.
White Box Testing
Full Source Code AuditFull visibility into source code and architectural configs to find deep, systemic logic flaws that surface-level testing might miss.
All engagements follow CREST and OWASP methodologies.
The Business Case
Proactive security testing is no longer just an IT requirement. Our reports are built to satisfy three core mandates:
Regulatory & Compliance
Mandatory evidence for ISO 27001 (Annex A.9), PCI DSS (Req 11.3), GDPR Art 32, and NHS DSPT frameworks.
Enterprise Sales Enablement
Satisfy procurement hurdles, vendor risk assessments, and enterprise customer security questionnaires with CREST-accredited evidence.
Cyber Insurance
Reduce premiums and ensure policy payouts by demonstrating proactive security posture to underwriters.
300% ROI of Prevention
For every £1 spent on testing, organisations avoid an average of £3 in breach costs (IBM UK Cost of a Data Breach report).
CREST-Accredited Penetration Testing
Precursor Security holds CREST company accreditation, the UK's most widely recognised standard for penetration testing quality and ethical conduct. CREST accreditation is examination-based: our testers must demonstrate live technical competency, not just hold a paper certificate.
What CREST accreditation means
Our penetration tests are delivered to a standard recognised by NCSC and government, not a self-certified standard. Individual tester certification requires passing rigorous technical examinations. Company accreditation requires demonstrating organisational security practices and ongoing quality assurance.
Our reports are accepted for
Recognised by regulators, auditors, and underwriters across the UK.
Full Penetration Testing Catalogue
Comprehensive penetration testing services tailored to your environment.
Internal Testing
Post-perimeter assessments targeting Active Directory, lateral movement, privilege escalation, and segmentation validation from inside your network.
Continuous Protection.
After The Test.
Your penetration test report should not gather dust. We feed your exact vulnerabilities directly into our 24/7 Managed SOC, building custom detection rules based on your specific attack surface and actively hunting for exploitation between annual tests. It is the difference between a point-in-time snapshot and genuine continuous exposure management.
Explore 24/7 Monitoring24/7 Threat Hunting
Continuous eyes-on-glass monitoring of your entire perimeter.
Custom SOC Rules
Alerts tuned specifically to the findings in your pentest report.
Real-time Containment
Immediate isolation of compromised assets before lateral movement.
Board Assurance
Prove to stakeholders that identified risks are actively monitored.
Plain-English definitions of the concepts behind this service, from our security glossary.
Ready to test your defences?
Book a free 30-minute scoping call. We identify which assessments apply to your environment, confirm scope in writing, and provide a fixed-price quote. No obligation. No day-rate surprises.
Frequently Asked Questions
Common questions about our network, web application, API, cloud, and mobile penetration testing services, methodologies, and deliverables.
We provide the full range of penetration testing services: internal network penetration testing, external network penetration testing, web application penetration testing, API security testing, cloud penetration testing, and mobile application penetration testing, alongside specialist services such as red team operations, wireless testing, and social engineering assessments. Every engagement is delivered by CREST-accredited testers and scoped individually to your environment.
Penetration testing services from Precursor Security start from £2,500 for a fixed-price engagement, with most projects ranging between £2,500 and £15,000+ depending on scope. External network testing starts from £2,500, web application testing from £3,750, and internal network testing from £6,250. Every quote is fixed-price after a free scoping call, with no hidden day rates.
Yes. Precursor Security holds CREST company accreditation, and our individual testers hold CREST Registered or Certified Tester status, the UK's government-endorsed standard for penetration testing competency. This means our penetration testing services are recognised as credible evidence for FCA cyber resilience requirements, NCSC ITHC, PCI DSS, NHS DSPT, ISO 27001 audits, and cyber insurance underwriting. You can verify our accreditation independently at crest-approved.org.
Penetration testing in the UK typically costs between £2,500 and £15,000+. A standard web application penetration test for a small-to-medium application averages £3,750-£6,250 for 3-5 days of testing. External network testing (1-20 IP addresses) starts from £2,500. Internal network testing for mid-sized organisations typically costs £6,250-£12,500 for a single Active Directory domain. Complex engagements covering multiple applications, large infrastructure, or cloud environments range from £10,000-£15,000+. All engagements are fixed-price, quoted after a free scoping call with no hidden day rates.
Active testing typically takes 2-8 days depending on scope. A standard web application test runs 3-5 days. External network testing (up to 20 IPs) runs 2-3 days. Internal network testing runs 5-8 days. The full engagement including scoping, testing, and report delivery typically spans 2-3 weeks from kick-off. A 30-day retest window is included in every engagement to verify your remediation efforts.