Advanced external infrastructure penetration testing

Protect your organisation from threats originating outside your network with our advanced external penetration testing service. Our infrastructure pen test examines your internet-facing systems, applications, services, and remote access technologies to identify vulnerabilities an attacker could exploit.

Evalian’s three-pronged approach offers a holistic assessment of external vulnerabilities, aiming not only to identify potential entry points for cyber adversaries but also to strengthen the security measures and settings that protect your organisation’s valuable data and resources.

Why external infrastructure penetration testing matters

As your organisation’s digital footprint grows through public servers, cloud services, remote access tools, APIs and web applications, so does the number of potential entry points available to an attacker.

An external infrastructure pen test provides an independent assessment of your internet-facing security controls, helping you understand whether weaknesses could lead to unauthorised access, data exposure or further compromise.

Protecting your digital perimeter

Your public-facing servers and services are the first thing an attacker sees. Misconfigurations, outdated software, and exposed ports can all provide a route into your network, so it’s essential to know exactly what’s visible and how it could be exploited.

Understanding your public attack surface

Attackers rarely rely on technical flaws alone. Leaked credentials, exposed API keys, and information sitting in public code repositories or breach databases can be just as useful to an attacker as a vulnerable server, and most organisations underestimate how much of this information exists.

Securing remote connectivity

With hybrid and remote working now standard, the way your employees connect to your network has changed. Whether using VPNs, Microsoft 365, or SharePoint, this becomes a critical part of your attack surface. A single weak or intercepted connection can undermine the rest of your security controls.

Common ways attackers target external infrastructure

Understanding how a hacker may approach an organisation’s external attack surface shows why comprehensive external penetration testing can provide more insight than a single vulnerability scan.

Exploiting public-facing servers and services

Attackers scan the internet for outdated software, open ports, and misconfigured services, looking for a foothold into your network.

Using leaked credentials and exposed data

Breached databases, exposed API keys, and information left in public code repositories give attackers a head start, often without touching your infrastructure directly.

Password spraying

Rather than brute-forcing a single account, attackers apply a small number of common passwords across many accounts at once. It’s a low-and-slow technique that evades typical lockout policies and, across a large enough user base, reliably yields results. 

Intercepting or abusing remote access

VPNs and collaboration platforms are designed to provide convenient access to corporate resources, but weaknesses in configuration, authentication or exposed credentials can increase the risk of compromise.

Our three-pronged methodology

A standard external infrastructure test typically focuses on your public-facing servers and services. That’s a useful starting point, but it doesn’t reflect how attackers actually operate. Our advanced penetration testing service adds two further layers of assessment to give you a genuinely comprehensive view of your external risk.

The three prongs feed each other. When OSINT or connectivity testing surfaces something new, such as a forgotten subdomain or a leaked credential, we bring it back into the perimeter assessment and test against it, rather than treating each phase as a separate exercise.

Digital perimeter assessment

We thoroughly evaluate your publicly facing servers and services. This is the digital equivalent of testing a building’s locks, alarms, and walls. Using automated tools alongside manual penetration testing techniques, we identify vulnerabilities in your public-facing infrastructure that could provide an entry point.

Unlike a one-off scan, this phase runs throughout the engagement: as OSINT and connectivity testing surface new information, we bring it back into the perimeter assessment and test against it.

• Reconnaissance and subdomain enumeration. Before active testing begins, we map your public-facing assets: websites, applications, network interfaces and server endpoints. We also identify subdomains linked to your primary domain, since each can run different technologies and host different services.
• Port and service identification. We scan for open TCP and UDP ports, identify the services behind them, and review versions and configurations for known weaknesses.
• Vulnerability identification and validation. We combine automated scanning with manual testing to find security weaknesses. Where the rules of engagement allow, we then validate that they can be exploited, so you receive confirmed findings rather than raw scanner output. We prioritise findings by severity and likelihood of exploitation.

Intelligence harvesting

We use Open-Source Intelligence (OSINT) techniques to gather and analyse publicly available information about your company and how an attacker could use it. This includes: 

• Domain information. We examine domain registrations and associated infrastructure, such as IP addresses, server locations, and contact details, to identify potential entry points.
• Email addresses and password leaks. We search breach and leak databases for email and password combinations linked to your domain. These point to staff and administrators whose credentials could enable unauthorised access, or attacks such as phishing and password spraying.
• Document metadata. Author names, software versions and editing times in public files can reveal your internal technologies and support social engineering.
• API leaks. We look for unsecured endpoints and misconfigured APIs that could expose data or provide an entry point. 
• Google dorks. We use advanced search syntax to find exposed credentials, sensitive files and administrative interfaces that are public but hard to find with ordinary searches.
• GitHub dorks. We search GitHub and similar platforms for hard-coded credentials, API keys and proprietary code that developers have published by accident.
• GitHub organisation analysis. We analyse your organisation’s public repositories and, where you grant access, private ones, for exposed secrets and other sensitive data.

Connectivity evaluation

We assess how your employees connect to your network and cloud services, and whether those connections are resilient against interception or unauthorised access.

• Remote access review. We review VPN configurations and other remote access points for weaknesses that could allow interception or unauthorised entry.
• Microsoft 365 and collaboration platform testing. We evaluate how you use Microsoft 365 (including SharePoint) and similar platforms, checking that authentication and access controls hold up against compromise.
• Password spraying. Login portals for VPNs, Microsoft 365 and SharePoint are prime targets for password spraying, so where it is in scope, we test how well they resist it. We agree timing and lockout thresholds with you in advance so that testing doesn’t lock out your users.

Together, these three prongs provide a comprehensive security assessment of your external attack surface, each playing a crucial role in strengthening your organisation’s cyber security posture.

Scoping and reporting

Every external infrastructure pen test starts with detailed scoping. We begin by defining the battlefield, e.g. target domains, any off-limits systems, and whether a black-box, white-box, or hybrid approach best suits your objectives. Scoping shapes everything that follows, including cost, depth, and the tools and techniques used.

• Black-box testing simulates an attacker with no inside knowledge of your systems.
• White-box testing gives the tester information up front, allowing a more focused and efficient test.
• Hybrid testing starts with limited knowledge and deepens the engagement based on initial findings.

Read more here about the differences between black-box testing and white-box testing.

Web applications 

Infrastructure testing covers how your applications are hosted, configured and exposed. If a web application is part of the agreed attack surface, we can assess it at that level. For thorough testing of application logic, authentication and authorisation, a dedicated web application penetration test is the better fit.

Reporting 

Your results don’t arrive as an email attachment. They’re available in SecureIQ, our UK-hosted online reporting and vulnerability-tracking platform, included with our penetration testing services.

You receive a detailed report with a prioritised remediation plan, so your team can focus on the issues most likely to be exploited. We can also advise on follow-up actions and remediation based on our findings. 

Why choose Evalian for external infrastructure testing?

Broader than a standard test

Rather than stopping at your public-facing servers, we combine perimeter testing with intelligence harvesting and connectivity evaluation, so you understand vulnerabilities that a standard test would miss.

Practical, risk-based reporting

You get a detailed remediation plan that prioritises the issues most likely to be exploited, so you can focus your resources where they’ll have the greatest impact. They’re delivered through SecureIQ, so you can track remediation without chasing email attachments or juggling spreadsheets.

Request a SecureIQ demo. 

Experienced and accredited specialists

Our testers are CREST-certified and have experience testing infrastructure across a wide range of sectors, so you can trust the findings reflect current best practice.

Long-term value

While an advanced assessment requires more upfront investment than a single-pronged test, it reduces the risk of a severe breach — and the financial and reputational damage that comes with it.

When should you test?

External testing is commonly carried out annually, after significant changes to your internet-facing infrastructure, and when a customer, insurer or framework requires independent assurance. It is widely used to support requirements under standards such as ISO 27001, Cyber Essentials Plus and PCI DSS.

SecureIQ stores your reports and vulnerability data by project and by test, giving you audit-ready evidence and a record of your testing over time. 

Even an advanced assessment is a point-in-time exercise and isn’t fail-safe, which is why regular retesting matters.

Speak to a member of our cyber security team to discuss your requirements.

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External infrastructure penetration testing FAQs

What is external infrastructure penetration testing?

External infrastructure penetration testing is security testing that assesses your organisation’s internet-facing systems, services and infrastructure for vulnerabilities an external attacker could exploit. It typically examines public-facing servers, network services, firewalls and remote access technologies. 

The aim is to find security flaws and understand whether they could lead to unauthorised access, data exposure or further compromise.

What is an infrastructure pen test?

An infrastructure pen test is a controlled security assessment of network infrastructure, servers, services and related technologies. An external infrastructure pen test approaches these systems from outside the organisation, simulating how a real-world attacker might identify and exploit weaknesses.

This differs from an internal infrastructure pen test, which assesses security from within the internal network and can provide insight into the potential impact of a compromised device, account or insider threat.

What is the difference between external penetration testing and vulnerability scanning?

Vulnerability scanning primarily uses automated tools to identify potential vulnerabilities. A pen test goes further by combining automated scanning with manual testing by experienced penetration testers.

This allows testers to investigate vulnerabilities, validate whether weaknesses can be exploited and understand their potential impact. The result is a more contextual security assessment, not just a list of scan results.

What does an external penetration test cover?

The scope depends on your requirements, but an external infrastructure penetration test can include internet-facing servers, network services, remote access technologies, and other publicly accessible infrastructure.

Our advanced service adds OSINT and credential exposure analysis to identify information an attacker could use, and connectivity evaluation to test how your people connect to your network and to platforms such as Microsoft 365.

Do you test web applications as part of an infrastructure pen test?

If a web application forms part of the agreed external attack surface, you can assess it as part of the engagement.

However, a dedicated web application penetration test may be more appropriate if you need comprehensive testing of application functionality, authentication, authorisation, and application-specific security flaws.

How does external penetration testing simulate a real-world attack?

Our penetration testers use controlled techniques to simulate real-world attacker behaviour within an agreed scope and rules of engagement.

This can include reconnaissance, identifying internet-facing services, analysing exposed information and testing vulnerabilities to understand whether an attacker could potentially gain unauthorised access.

The objective is to provide realistic insight into your security weaknesses without conducting uncontrolled or malicious activity.

Can penetration testing identify weaknesses in firewalls and remote access?

Yes. An external infrastructure pen test can assess exposed firewall configurations, network services, VPNs and other remote access points for weaknesses.

Testing can identify configuration issues, exposed services, and other security flaws that could give an attacker a potential route into the environment.

Are your penetration testers CREST certified?

Yes. Our penetration testers are CREST certified and have experience conducting infrastructure testing across a range of sectors.

Using CREST-certified penetration testers provides assurance that experienced specialists deliver the engagement in line with recognised industry practices.

How long does an external infrastructure penetration test take?

The duration depends on the scope of the penetration testing service, including the number of targets, the testing approach and the depth of assessment required.

During scoping, we agree on the systems to be tested, testing methodology, objectives and expected timescales before the engagement begins.

Is external penetration testing a one-off exercise?

An external penetration test provides a point-in-time assessment, but your internet-facing infrastructure and attack surface can change as systems, applications and services are added or modified.

Regular external penetration testing can help organisations identify newly introduced vulnerabilities, validate remediation work and maintain visibility of their external security posture over time.

Why does password spraying work?

Password spraying relies on the likelihood that, across a large number of users, some will have chosen a very common password such as “password”, “123456” or “admin”. Instead of trying many passwords against one account, which triggers lockouts, the attacker tries a few common passwords against many accounts. Because each account sees only a few failed attempts, this can slip under lockout policies and detection rules that watch for rapid failures on a single account. Even a low success rate across hundreds or thousands of accounts can produce working logins.

Strong password policies, multi-factor authentication and monitoring for failed logins across accounts (not just per account) all reduce the risk.

Get a quote for external infrastructure testing 

If your organisation needs help running a penetration test on an application or infrastructure, we’re here to help. We can assess your environment and run a full penetration test. We can also advise you on any follow-up actions or remediations from our findings. Contact us for a friendly chat.