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Network Penetration Testing Services

Network penetration testing simulates the activity of an external attacker probing your internet-facing infrastructure, or an internal attacker who has gained a foothold on your network. Both scenarios remain among the most common attack vectors in real-world breaches, and both demand more depth than vulnerability scanning alone can provide.

RedSecLabs delivers CREST-certified network penetration testing across internal, external, and segmentation testing scenarios. Our testers combine manual exploitation depth with breadth across the technologies you actually run. Active Directory, Linux server estates, network appliances, OT/IoT segments, cloud-edge gateways.

Every engagement produces actionable findings prioritised by exploitability, not 200-page reports nobody reads, but the 15-20 issues that materially reduce your real risk.

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
Who this is for

This service is a fit if you’re..

1
Internal infrastructure
Organisations testing internal network segmentation, AD, and lateral movement paths.
2
External attack surface
Companies wanting an outside-in view of what an attacker sees from the public internet.
3
PCI DSS Requirement 11
Merchants and service providers needing the network pentest evidence for QSA assessment.
CREST
Certified testers
Internal & external
Full network scope
Manual
Real exploitation
5-10 days
Typical engagement

What is network penetration testing?

Network penetration testing is the structured, manual assessment of network infrastructure for exploitable security weaknesses. It comes in three primary forms: external network testing (assessing your internet-facing perimeter as a remote attacker would); internal network testing (assessing post-foothold lateral movement, privilege escalation, and access to crown-jewel systems); and segmentation testing (validating that network controls between zones. DMZ, CDE, OT, dev/prod, actually enforce the boundaries they claim).

Network pentesting goes deeper than vulnerability scanning. Scanners find known vulnerabilities; network pentesters find what scanners miss, misconfigurations, weak credentials, exposed admin interfaces, unsegmented zones, and the attack paths that chain individual minor issues into serious compromise.

What network testing delivers:

Validated picture of external attack surface from a real attacker perspective

Identification of internal lateral movement and privilege escalation paths

Verification of network segmentation between security zones

Evidence supporting PCI DSS Requirement 11.4, ISO 27001 A.12.6.1, SOC 2 CC7.1

Discovery of vulnerable legacy or shadow infrastructure

Concrete remediation guidance prioritised by exploitability

Most organisations need at least annual network testing, and quarterly testing for internet-facing services in high-target sectors like financial services or e-commerce.

Why network testing matters

Network compromise remains the most common pre-cursor to serious breach. Initial access via internet-facing services, lateral movement through unsegmented networks, and privilege escalation to domain admin, these are the steps that turn a single vulnerability into a full enterprise compromise. Network pentesting is the only practical way to validate that all three steps fail for a determined attacker against your environment.

Network testing is also a baseline compliance requirement under every major framework. PCI DSS Requirement 11.4 mandates annual penetration testing of in-scope networks; ISO 27001 Annex A.12.6.1 expects regular technical compliance review; SOC 2 CC7.1 requires evidence of continuous monitoring and assessment.

Without quality network testing, organisations face:

Undetected external attack paths into critical systems

Unvalidated network segmentation that fails in real attacks

Privilege escalation paths reaching domain admin

Compliance failures across PCI DSS, ISO 27001, SOC 2

Shadow infrastructure invisible to existing security tooling

False confidence from scan-only assessments

Network pentesting is the single highest-value security investment for most organisations operating any significant network estate.

Who needs network penetration testing?

Any organisation operating internet-facing services or internal networks with sensitive systems benefits from regular network testing:

Financial services and fintech

E-commerce (PCI DSS scope)

SaaS and technology

Healthcare and HealthTech

Defence and government

Hybrid and cloud-native

Manufacturing and OT

Education and research

Organisations subject to PCI DSS, ISO 27001, or SOC 2 typically need at least annual network testing as core compliance evidence.

Our Network Testing Methodology

CREST-aligned methodology combining established frameworks (NIST SP 800-115, OSSTMM, MITRE ATT&CK) with hands-on exploitation depth.

01

Scoping & Rules of Engagement

We agree the test type (external, internal, segmentation), in-scope target ranges, escalation contacts, testing windows, and any out-of-scope restrictions.

02

Reconnaissance & Asset Discovery

For external tests, OSINT and DNS discovery to identify the full attack surface, often including assets your IT team has lost visibility of.

03

Service & Vulnerability Enumeration

Detailed port scanning, service fingerprinting, and vulnerability identification across the in-scope estate.

04

Manual Exploitation

Confirmed vulnerabilities exploited to demonstrate real impact, credentials harvested, services compromised, configuration weaknesses exploited.

05

Privilege Escalation

Post-compromise privilege escalation paths explored, local admin to domain admin, service account to user impersonation, kernel and misconfiguration paths.

06

Lateral Movement

Demonstration of movement across the network, testing segmentation effectiveness and reach toward objective systems.

07

Reporting & Walk-Through

Detailed findings with exploitation evidence, CVSS plus exploitability prioritisation, and live walk-through with your technical team.

08

Remediation Retest

Critical and high findings re-tested after your team remediates, with formal validation included in scope.

External infrastructure tests typically 3-5 days; internal network tests 5-10 days; combined external + internal engagements 8-15 days depending on estate size.

What you receive

Every network pentest engagement with RedSecLabs includes:

  • Signed rules of engagement and scoping document
  • Executive summary for board and management consumption
  • Detailed technical findings with exploitation evidence
  • CVSS-rated severity with exploitability context
  • Practical remediation guidance for every issue
  • Network attack-path diagrams for chained findings
  • Walk-through session with your technical team
  • Remediation retest of critical and high findings

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 network testing

Network testing is where the gap between automated scanning and skilled offensive security shows most starkly. Our testers manually chain misconfigurations, weak credentials, and exposed services into the attack paths a real adversary would use, finding the issues that scanners report as noise but that genuinely enable breach. Reports prioritise by exploitability, not just CVSS.

CREST-certified testers on every engagement
Manual exploitation, not scanner output
Attack-path analysis for chained findings
PCI DSS, ISO 27001, SOC 2 compliance-ready
Remediation retest included
1-2 week engagement start

Schedule Your Network Pentest

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.

Web App Pentesting

CREST Penetration Testing

Vulnerability Assessment

Frequently Asked Questions

External tests assess your internet-facing perimeter from a remote attacker perspective, what an attacker without prior access could compromise. Internal tests simulate post-foothold activity from someone who has reached your internal network (e.g. via phishing or VPN access), testing privilege escalation and lateral movement. They produce very different findings; most organisations need both at least annually.

Yes, segmentation testing specifically validates that network controls between zones (DMZ, CDE, OT, dev/prod) enforce the boundaries they claim. This is a PCI DSS Requirement 11.4.5 mandate for any organisation relying on segmentation to reduce PCI scope. We deliver it as a focused engagement or as part of broader internal testing.

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.

For PCI DSS compliance, at least annually plus after significant infrastructure changes. For ISO 27001 / SOC 2, annual testing is common. For high-risk environments (financial services, e-commerce processing high volumes), quarterly external testing of internet-facing services is best practice.

External infrastructure tests typically £4,000-£10,000; internal network tests £8,000-£20,000; combined engagements £12,000-£25,000; complex multi-site engagements £25,000-£60,000+. CREST premium adds 10-20%. Fixed-fee quotes within 48 hours of scoping.

Yes, for IaaS environments (servers running in AWS/Azure/GCP) network testing applies as normal. For PaaS and managed services, additional cloud-specific testing methodology applies, see our cloud penetration testing pages for AWS and GCP specialised testing.
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 1-2 page 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 an 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. No surprise invoices.
  2. 2
    Test plan & authorisation
    Written test plan covering methodology, targets, and rules of engagement. Authorisation letter signed before any testing begins.
  3. 3
    CREST-aligned execution
    Senior tester runs the engagement. Critical findings flagged immediately during testing. Daily updates if you want them.
  4. 4
    Technical + executive report
    Detailed technical findings with reproduction steps. Board-ready executive summary. Delivered within agreed working days.
  5. 5
    Remediation call & retest
    Walkthrough with our lead tester. Retest of remediated findings within the agreed window. Confirmation letter for your auditors.
Engagement scope

What shapes the quote

Small scope
Single app, focused scope, smaller surface. 5-7 working days.
Medium scope
Multi-role platform, several user types, integrations. 8-12 working days.
Enterprise scope
Complex environment, multiple targets, compliance evidence. 12-25 working days.
Fixed-scope quote within 1 working day
No surprise invoices, no scope-creep. We commit to a number before you commit to us.
Sample report
See exactly what we deliver
Download a redacted RedSecLabs penetration test report. Same format, same depth, same clarity as the report your team will receive.
Download sample report
Why RedSecLabs

Grounded reasons clients choose us

⚑
UK-based team
Testers based in the UK. Data stays within UK/EU jurisdiction for sensitive engagements.
❄
CREST member company
CREST-aligned methodology. Senior testers hold CREST CRT or CCT certifications.
⚙
Manual testing, not scanner-only
Automated scanners catch the obvious. Our human testers find the issues that matter.
✎
Clear executive reporting
Reports your board can read and your developers can act on. No jargon padding.
♚
Compliance-aware delivery
PCI, SOC 2, ISO 27001, DORA, GDPR. We map findings to your compliance framework.
↺
Retest support included
Free retest of remediated findings within agreed window. Confirmation letter for auditors.
Related services

Often paired with this engagement

Web App Pentesting →
Cover application layer too.
AWS Cloud Pentesting →
Cloud-native infrastructure.
PCI DSS Compliance →
Where network pentest evidence is required.
Red Team Assessment →
Goal-based adversary simulation.
Security Architecture Review →
Identify design-level weaknesses.
📞 Call us Book a call