External Network Penetration Testing
Your perimeter looks secure. Let's prove it.
Accreditations and memberships
External Network Security Testing
What is external penetration testing?
Securing your external network involves protecting the systems and services that are exposed and accessible from the internet. This includes firewalls, network gateways, remote access services, and any infrastructure that forms your organisation's external attack surface.
Because these systems are publicly reachable, they are continuously probed by attackers looking for misconfigurations, exposed services, and known vulnerabilities. A single weakness on the perimeter can provide an entry point into internal systems or sensitive data.
External infrastructure penetration testing simulates real-world attacks against your internet-facing systems to identify what an attacker could discover and actually exploit.
The goal is not just to find vulnerabilities, but to understand exposure, validate risk, and prioritise remediation based on real impact.
Who Needs This
Who needs external penetration testing?
Organisations with remote access services
Businesses hosting public-facing infrastructure
PCI DSS, ISO 27001, and Cyber Essentials Plus
Organisations preparing for internal testing or red teams
Our Pentest Methodology
How we conduct external penetration testing
Scoping & Rules of Engagement
We agree the target IP ranges, domains, and testing boundaries with you before any active work begins. You specify constraints - timing windows, excluded systems, acceptable techniques - and we operate strictly within them.
Reconnaissance & Asset Discovery
We map your external attack surface through passive and active techniques: identifying servers, cloud assets, exposed services, subdomains, and infrastructure attributable to your organisation from the position of an unauthenticated attacker.
Vulnerability Analysis
Manual enumeration combined with targeted scanning to identify outdated software, exposed management interfaces, misconfigured services, and exploitable weaknesses across your external footprint. Every finding is manually validated.
Exploitation & Validation
Where vulnerabilities exist, we attempt controlled exploitation to confirm real-world impact. Brute force protections, default credential testing, and chained attack paths are assessed to determine what an attacker could actually achieve from initial access.
Reporting & Debrief
Findings are documented with reproduction steps, severity scoring, and remediation guidance mapped to CVE, CVSS, and MITRE ATT&CK where applicable. We provide methodology notes suitable for QSA and auditor requirements, and offer a debrief session to walk through findings.
Scope & coverage
What external infrastructure penetration testing covers
The scope of an external infrastructure assessment depends on what your organisation exposes to the internet. During scoping we confirm exactly what falls within your specific engagement.
Below are the asset classes we typically identify during testing:
Remote access services
VPN gateways, RDP, SSH, and similar remote access endpoints. These are among the most targeted services on the perimeter and are assessed for weak credentials, known vulnerabilities, and misconfigurations.Firewalls, gateways, and edge devices
Perimeter appliances and any exposed management interfaces. Misconfigured firewall rules and publicly accessible admin panels are a common source of high-severity findings.Mail infrastructure
Mail servers, submission ports, and related services, including an assessment of SPF, DKIM, and DMARC configuration of your domain's exposure to spoofing.DNS and domain hygiene
DNS records, subdomain enumeration, and certificate transparency data to identify shadow IT, forgotten services, and misconfigurations that extend your attack surface beyond what is obviously in scope.Web services and APIs
Internet-facing web applications, admin panels, and APIs that form part of the infrastructure scope. Full application-layer testing is available as a separate web application penetration test.Cloud edge assets
Internet-facing infrastructure hosted on AWS, Azure, GCP, and similar platforms. Cloud-hosted assets are assessed in the same way as on-premise infrastructure, from the position of an external attacker with no prior access.
Key Deliverables
What's included in the assessment?
Executive Report
Technical Report
Debrief Session
Free Retesting
Attack Surface Center Access
Consultant-led Testing
Pricing
From £1,800
for external network penetration testing
Not sure where your network fits? A 30-minute scoping call is free and gets you a fixed written quote.
No obligation · Strictly confidential · Quote within one business day
Pricing Examples
| Small network (1-25 IPs) | £1,800 - £2,500 |
| Medium network (26-50 IPs) | £2,400 - £3,200 |
| Large network (51-100 IPs) | £3,200 - £4,000 |
| Enterprise network (100+ IPs) | £4,000+ |
What's Included
- Fixed-price proposal within one business day
- Manual, consultant-led testing. Not automated scans
- Report within 2 business days of testing completion
- Free focused retesting included to verify remediation
- No obligation quote, all enquiries are fully confidential
Common Questions
External network penetration testing - frequently asked questions
Typical external penetration tests take 3-5 days depending on scope. Reports are delivered within 2 business days of testing completion.
If you're preparing for your first assessment, our guide to scoping a network penetration test covers what information to have ready.
External testing is designed to safely simulate real attacks without causing service outages. We coordinate timing and agree acceptable testing windows in advance, and can schedule testing during off-peak hours if preferred.
There is an inherent element of risk in any penetration test or vulnerability scan. During scoping we ask about legacy, sensitive, or business-critical services to ensure extra care is taken where needed.
External penetration testing is a requirement or recommended control under several major frameworks:
- PCI DSS Requirement 11.4 mandates penetration testing of all cardholder data environment boundaries, including internet-facing systems. Annual testing at minimum, with additional testing after significant changes.
- ISO 27001 expects regular security testing as evidence of ongoing vulnerability management and technical security controls.
We can provide methodology notes and structured reporting that supports QSA and auditor evidence requirements for each of these frameworks.
Annual testing at minimum. We recommend additional testing after significant infrastructure changes, new service deployments, or following any security incidents.
External testing focuses on internet-facing systems accessible to any attacker. Internal penetration testing assumes an attacker has already gained access to your internal network. Both are recommended as complementary assessments.
Yes, cloud-hosted infrastructure on AWS, Azure, GCP, and other platforms that form part of your external attack surface is included in our external testing scope.
No, our external penetration testing is performed remotely. We do not require any physical access to your premises or infrastructure for this service.
You can request an external penetration testing quote using the form on our quote page. Include your IP ranges or subnet size, whether cloud infrastructure is in scope, and your preferred testing window. We respond with a fixed-price written proposal within one business day. External network testing starts from £1,800.
Ready to test your perimeter network security?
Get a fixed-price quote within 24 hours. Our team will review your external footprint and provide a tailored scope that fits your budget and security needs.