What is Infrastructure Penetration Testing? Methods and Tools

Infrastructure penetration testing is a form of infrastructure security testing, designed to simulate real-world cyberattacks on your organisation’s internal or external networks, systems or devices. For businesses, particularly those in regulated sectors such as healthcare, manufacturing, energy, and finance, it is one of the most effective ways to uncover vulnerabilities and strengthen your cyber resilience.

By replicating the tactics of skilled attackers, infrastructure penetration testing provides clear and actionable insight into your security posture, and how you can improve it. From exposed internet-facing systems, to insecure internal configurations, both your external and internal environments are put to the test.

In this article, you will learn what infrastructure penetration testing involves, the tools and methodologies used by accredited experts, and how it maps to your compliance requirements.

Key Takeaways

• Infrastructure penetration testing simulates real-world cyberattacks to identify and help you fix vulnerabilities in your internal and external networks, systems, and devices.
• It helps UK organisations in regulated sectors like healthcare, energy, finance and manufacturing meet and demonstrate their compliance with regulatory frameworks such as ISO 27001, PCI DSS, NIS2, DORA, and GDPR.
• Testing can be black-box, grey-box, or white-box, with methodologies like OSSTMM, PTES, and NIST ensuring thorough and repeatable results.
• Typical vulnerabilities uncovered include misconfigured firewalls, outdated systems, weak credentials, insecure remote access, and poor segmentation.
• Partnering with a CREST and CHECK accredited provider like DigitalXRAID ensures high quality testing, actionable remediation guidance, and ongoing cyber resilience.

What is Infrastructure Penetration Testing?

Infrastructure penetration testing is a targeted security assessment that simulates real-world cyberattacks on your organisation’s core systems, networks, and connected technologies. Unlike application penetration testing, which focuses on individual applications, infrastructure testing evaluates the backbone of your IT environment, from servers and firewalls to cloud deployments and operational technology.

The aim of these tests is to identify vulnerabilities in your cyber security before an attacker does. By safely exploiting weaknesses under controlled conditions, you gain a clear picture of your cyber resilience, the potential business impact of a breach, and the steps you can take to strengthen your defences.

Key goals of infrastructure security testing

Infrastructure security testing is an important investment into your service delivery, protecting your operations, data, and reputation from potentially devastating attacks.

Infrastructure pen testing aims to:

• Identify exploitable vulnerabilities in your internal and external infrastructure.
• Test the effectiveness of your security controls and configurations.
• Reduce your cyber risk and, ultimately, business risk, by enabling timely remediation.
• Provide evidence for compliance audits and customer assurance if you operate in a regulated sector.

Internal vs. external infrastructure vulnerabilities

Internal infrastructure penetration testing simulates an attack from a hacker with inside access, such as a compromised employee account or a device that’s connected to your network. It reveals risks from weak access controls, poor segmentation, and unpatched internal systems.

External infrastructure penetration testing targets internet-facing assets including your firewalls, email servers, VPNs, and cloud gateways, to identify entry points for external attackers.

A really robust security strategy must address both your internal and external infrastructure. Attackers frequently combine external and internal tactics, pivoting from a compromised public facing service into your internal network to evade detection.

How infrastructure pen testing supports cyber resilience

By proactively identifying and remediating vulnerabilities, infrastructure testing reduces the likelihood of a successful attack on your business. It also provides you with evidence for compliance audits and customer assurance, showing that your organisation is committed to safeguarding data and critical services.

Why Infrastructure Pen Testing Matters

Your IT infrastructure is the foundation that your operations depend on. Every email server, firewall, switch, cloud environment, and remote access point forms part of the attack surface that cybercriminals are actively seeking to exploit.

For UK organisations, especially if you’re operating in a regulated or critical sector, the stakes are high. A single vulnerability can trigger a chain of events that lead to downtime, data loss, or significant reputational damage.

Infrastructure penetration testing offers a controlled, expert-led way to uncover weaknesses before they can be exploited. It provides a realistic view of your cyber resilience, highlighting both technical flaws and procedural gaps that automated scans alone cannot detect.

Risks to critical infrastructure sectors

Organisations in sectors such as healthcare, energy, manufacturing, and financial services are prime targets for sophisticated cyberattacks. Disruption to these sectors can have serious consequences, from patient care delays to supply chain failures.

Recent NCSC threat reports show a sharp rise in ransomware campaigns targeting UK businesses in critical sectors, often exploiting weak remote access points or outdated systems.

The impact of cyberattacks on operational continuity

For providers of essential services, the operational and regulatory stakes are high. A successful breach in critical infrastructure industries can lead to:

• Prolonged downtime, halting public services
• Significant financial losses from remediation and fines
• Reputational damage affecting the public’s trust
• Regulatory investigations and penalties

Infrastructure penetration testing provides the intelligence you need to close gaps and fix vulnerabilities before they are exploited.

Common vulnerabilities found in networks

Typical vulnerabilities that are uncovered during infrastructure penetration testing include:

• Misconfigured firewalls and access control lists (ACLs) that allow unnecessary inbound or outbound traffic, increasing your exposure to unauthorised access.
• Legacy operating systems and end-of-life software that no longer receive security updates, leaving known vulnerabilities unpatched.
• Flat network architectures with no segmentation, allowing an attacker to move laterally across systems once they gain initial access.
• Default, weak, or reused credentials on critical devices such as routers, switches, and administrative interfaces, which can be easily guessed or brute forced.
• Insecure remote access solutions, including poorly configured VPNs or remote desktop services that are exposed to the internet without multi-factor authentication.
• Unmonitored third-party connections that provide attackers with indirect access to internal systems.
• Poor logging and monitoring practices that delay the detection of malicious activity, increasing the dwell time of attackers.

Addressing these vulnerabilities before they’re exploited is far less costly than responding to a successful breach. Infrastructure penetration testing ensures you stay ahead of these weaknesses and know how to fix them before an attack occurs.

Infrastructure Penetration Testing Methodologies Explained

The value of infrastructure penetration testing depends on the methodologies that are used by the ethical hacker. The right approach ensures realistic results and actionable outcomes.

Black box, grey box and white box testing methodologies

• Black box pen testing: This means the tester has no prior knowledge of your systems, simulating an external attacker’s approach, which is ideal for perimeter security assessments.
• Grey box pen testing: The tester has partial knowledge or limited access, mimicking the perspective of an attacker who has gained an initial foothold.
• White box testing: The tester has full access to your network diagrams, credentials, and system details in white box testing, enabling a deep assessment of your security controls.

Industry frameworks

Working with a provider that follows recognised frameworks ensures that your testing is thorough, repeatable, and comparable year after year. Commonly used established frameworks for infrastructure testing include:

• NIST SP 800-115: A structured approach covering planning, discovery, attack, and reporting phases.
• OSSTMM: Emphasises operational security and measurable metrics.
• PTES: Covers everything from pre-engagement interactions to threat modelling and post-test reporting.

The OSSTMM (Open Source Security Testing Methodology Manual)

The OSSTMM is an internationally recognised methodology for testing and measuring operational security in both digital and physical environments. Unlike some frameworks that focus primarily on technical vulnerabilities, the OSSTMM takes a broader view, assessing how well security controls work in real-world conditions. It measures not only the presence of vulnerabilities, but also the effectiveness of your operational processes, trust relationships, and resilience to different classes of threats.

In the context of infrastructure penetration testing, the OSSTMM provides:

• A standardised scoring system that allows results to be compared over time or across different parts of your organisation.
• Coverage of multiple security channels, including human factors, wireless communications, data networks, and physical access.
• Metrics-driven insights that link test results to measurable risk reduction, enabling your security teams to prioritise improvements effectively.

Because the OSSTMM is open sourced, it benefits from continuous input from the global security community. When used by a skilled, accredited provider, it ensures that your infrastructure is tested against real world attack conditions, not just compliance checklists.

Choosing a provider who aligns with these recognised frameworks ensures consistency, thoroughness, and credibility in your results.

Choosing the right approach based on risk profile

Organisations in highly regulated sectors may opt for white box testing to ensure complete coverage, while those seeking to test external resilience might choose a black-box approach. A blended model often delivers the most realistic and comprehensive insights, but the key is to partner with a penetration testing provider that can identify and deliver the approach that best fits your business.

Learn more about the criteria for choosing the right penetration testing provider.

Tools Used in Infrastructure Penetration Testing

Professional infrastructure testing relies on specialist cyber security tools as part of the process, used by accredited experts in controlled environments.

Scanning tools

• Nessus, by Tenable, and Nmap are widely used to discover network assets, identify open ports, and detect known vulnerabilities.
• These tools help to create an attack surface map, guiding further targeted testing that may need custom exploits and a more creative approach to think like a hacker and breach your network or system.

Exploitation tools

• Metasploit and Cobalt Strike are used to safely exploit identified vulnerabilities, demonstrating the potential impact of a successful attack.
• Controlled exploitation validates the severity of findings and prioritises remediation efforts.

Infrastructure-specific tools for ICS/SCADA environments

Critical infrastructure operators often use industrial control systems (ICS) and supervisory control and data acquisition (SCADA) environments. Tools like GRASSMARLIN or Wireshark help to map and analyse these specific network technologies, ensuring that tests are performed without disrupting operations.

Infrastructure Pen Testing & Compliance Requirements

Infrastructure testing is not only a security best practice, but a way to demonstrate your compliance with security frameworks.

Pen testing’s role in compliance frameworks

In addition to the cyber security benefits, penetration testing for compliance verifies your security measures against legal, regulatory, and industry requirements.

For UK and EU based organisations, the most relevant frameworks and regulations include:

• ISO 27001 – While not a mandatory control, penetration testing supports ISO 27001’s Annex A.12.6.1 (technical vulnerability management) and A.18.2.3 (technical compliance review). Tests should target high risk assets with results, remediation evidence, and retesting documented in your ISMS. Annual testing, plus additional tests after major changes, is considered best practice.
• DORA (Digital Operational Resilience Act) – DORA is applicable to EU financial services (FS) entities, anyone conducting business with EU-based FS institutions, and their IT providers. It requires annual risk-based security testing for critical functions, with Threat-Led Penetration Testing (TLPT) at least every three years for certain firms.
• NIS2 Directive – NIS2 covers critical infrastructure sectors such as energy, healthcare, transport, and digital infrastructure. It requires proactive vulnerability management, effective security testing, and evidence of cyber resilience. Penetration testing is a practical way to meet these obligations, particularly when aligned to service criticality.
• GDPR and UK Data Protection Act – Article 32 of GDPR requires regular testing, assessment, and evaluation of security measures protecting personal data. Penetration testing provides clear evidence of due diligence for systems that process sensitive information.
• PCI DSS – Mandatory for any organisation storing, processing, or transmitting cardholder data, PCI DSS penetration testing requires internal and external penetration testing at least annually and after any significant system change. Tests must cover both network- and application-layer vulnerabilities, as well as segmentation controls.

Choosing a CREST or CHECK accredited provider ensures that your tests meet regulatory expectations and produce audit-ready evidence.

Mapping testing outputs to compliance reporting

High quality penetration testing service providers deliver structured, standards aligned reports that map any uncovered vulnerabilities to your relevant regulatory or framework controls.

For example:

• PCI DSS Requirement 11.3 mapped to test results for network and application layers
• ISO 27001 Annex A.12.6.1 linked to vulnerability management findings and remediation plans
• GDPR Article 32 linked to evidence of secure configurations and patch management

This mapping makes audits more straightforward by providing regulators and certification bodies with exactly what they need in a clear and structured way. It also enables you to consolidate evidence across multiple frameworks, reducing duplication and ensuring that your compliance documentation stays current.

When done correctly, compliance-focused penetration testing is a powerful way to strengthen both your regulatory position and your operational resilience, giving you the confidence that your infrastructure can withstand real-world threats while always being audit-ready.

How DigitalXRAID Delivers Infrastructure Penetration Testing

DigitalXRAID’s CREST and CHECK accredited services can help you to:

• Identify and fix vulnerabilities before attackers exploit them
• Demonstrate compliance to regulators and auditors
• Reduce the likelihood and impact of cyberattacks
• Protect your operations, reputation, and customer trust

CREST-accredited methodology and process

As a CREST and CHECK accredited provider, DigitalXRAID follows a rigorous methodology:

1. Scoping and planning: Define objectives, scope, and constraints.
2. Reconnaissance: Gather intelligence on systems and network topology.
3. Vulnerability assessment: Identify weaknesses using manual and automated tools.
4. Exploitation: Safely exploit vulnerabilities to demonstrate potential impact.
5. Reporting: Deliver a detailed, prioritised report with remediation guidance.
6. Retesting (Optional): Verify that issues have been resolved effectively.

Continuous infrastructure testing and SOC integration

Infrastructure threats evolve rapidly. DigitalXRAID offers continuous testing and integration with our Managed SOC services to provide 24/7 monitoring, detection, and response to cyber security threats. This approach reduces the window of exposure between scheduled tests.

Example use cases from UK sectors

DigitalXRAID’s infrastructure penetration testing services are trusted by leading UK organisations across a range of sectors. These examples illustrate how tailored, compliance-focused testing protects their critical systems, meets their regulatory obligations, and delivers ongoing assurance to their operations.

Crowe UK – Safeguarding a multi-office network for compliance and insurance requirements

Sector: Professional Services | Type: Internal and External Infrastructure Testing | Frequency: Quarterly

Crowe UK, a leading audit, tax, advisory, and risk firm with over 1,300 staff across multiple offices in the UK wanted to go beyond automated vulnerability scanning to meet the requirements of their cyber insurance provider.

While Crowe UK already performed weekly automated scanning, they recognised the limitations of automated-only security checks. They needed expert led penetration testing to simulate real-world attack techniques and identify vulnerabilities that scanners alone might miss.

DigitalXRAID worked with Crowe UK to scope quarterly infrastructure penetration tests. Using advanced OSSTMM methodologies, our testers carried out comprehensive reconnaissance, active scanning, authentication testing, and encryption verification, assessing both their perimeter and internal network resilience.

The results included a detailed risk summary, vulnerability prioritisation, and clear remediation guidance. Crowe UK now benefits from a consistent testing framework that meets insurance requirements, strengthens security governance, and ensures rapid reporting to both internal stakeholders and external partners.

Augustus Oils – Securing external infrastructure in the manufacturing supply chain

Sector: Manufacturing & Supply Chain | Type: External Infrastructure Testing | Frequency: Regular

Augustus Oils, a premier supplier to the global flavour and fragrance industry, wanted assurance that its external facing infrastructure was protected against exploitation. As a business that bridges the gap between producers and global customers, maintaining operational integrity is critical to their business continuity and brand reputation.

DigitalXRAID delivered targeted external infrastructure penetration testing, beginning with precise scoping to maximise value. Our team conducted thorough reconnaissance and attack simulations, including port scanning, service fingerprinting, authentication testing, and SSL/TLS configuration checks.

The final report delivered by DigitalXRAID provided a clear, prioritised view of their cyber security risks, along with recommended remediation actions. Regular testing now gives Augustus Oils confidence in its resilience, ensures cyber risk is visible at board level, and protects sensitive commercial operations from potential compromise.

Breast Cancer Now – Strengthening internal and external resilience for a national charity

Sector: Charity & Healthcare Support | Type: Internal and External Infrastructure Testing, Web Application Testing | Frequency: Regular

Breast Cancer Now, the UK’s leading breast cancer research and support charity, undertook regular penetration testing to meet insurer and regulator expectations, and to maintain robust defences for their IT infrastructure.

DigitalXRAID delivered both internal and external infrastructure tests, plus targeted web application testing. Activities included open port analysis, network monitoring, active scanning, authentication testing, and encryption assessment, all following advanced, industry-recognised methodologies.

The results gave Breast Cancer Now a comprehensive view of their security posture, clear remediation priorities, and evidence of compliance for regulatory and insurance purposes. Regular penetration testing has enhanced their Cyber Essentials certification efforts, complemented vulnerability scanning, and provided a deeper level of assurance against evolving cyber threats.

These examples show how infrastructure penetration testing is not only a defensive measure, but also a compliance enabler and business continuity safeguard.

Whether for insurance mandates, supply chain security, or protecting sensitive data, regular testing with a CREST and CHECK accredited provider like DigitalXRAID ensures your infrastructure can stand up to both regulatory scrutiny and malicious cyber attacks.

Strengthen Your Infrastructure Security with DigitalXRAID

Protecting your core systems requires more than just firewalls and antivirus software. Infrastructure penetration testing from DigitalXRAID, including both external testing services and internal testing services, uncovers the vulnerabilities that matter most to your business, helping you to stay ahead of evolving threats and regulatory demands.

As a CREST and CHECK accredited UK provider, DigitalXRAID delivers thorough, compliance-ready security assessments tailored to your risk and regulatory profile. Whether you need a one-off test or continuous coverage, our experts provide the insight and support you need to secure your operations.

Get in touch today to discuss your infrastructure testing needs.

FAQs

What’s the difference between infrastructure and application pen testing?

Infrastructure testing focuses on your networks, servers, and core systems, while application testing targets specific software or web applications.

How often should infrastructure pen testing be done?

At least annually, and after significant changes such as system upgrades, mergers, or incidents. Depending on your industry and operations, it may be advisable to test more regularly.

What is involved in a typical infrastructure pen test?

Scoping, reconnaissance, vulnerability assessment, exploitation, and reporting, with optional retesting.

How do I choose between black-box and white-box testing?

Black-box testing is ideal for securing your external defences, while white-box testing provides a comprehensive view of your internal systems. Grey-box offers a balance of both.

Can infrastructure pen testing help with compliance audits?

Yes. Reports can be mapped directly to compliance frameworks like PCI DSS, and NIS2.

What should I expect in the final report?

A detailed breakdown of vulnerabilities, severity ratings, remediation steps, and supporting evidence.

Is automated scanning enough for infrastructure testing?

No. Automated scans are a useful first step, but lack the depth, context, and creativity of a human-led penetration test.

How is infrastructure pen testing priced?

Costs vary by scope and complexity, but they typically range from £5,000 to £25,000 depending on your architecture.