Penetration testing helps Irish businesses discover whether weaknesses in their IT systems could be exploited by an attacker. Unlike an automated vulnerability scan, a penetration test involves authorised security specialists attempting to demonstrate how identified weaknesses might affect real systems, applications and data.
This guide explains what penetration testing involves, the different types of tests available, how it compares with vulnerability scanning, and how to prepare for an assessment. It is intended for business owners, IT managers and decision-makers who want to understand the process before commissioning a test.
Key Takeaways
- Penetration testing uses controlled, authorised techniques to identify and demonstrate exploitable security weaknesses.
- Internal, external, web application, API and cloud tests address different parts of an organisation’s technology environment.
- Automated vulnerability scanning and penetration testing serve different purposes and work best together.
- Clearly defined scope, written authorisation and agreed rules of engagement help reduce disruption and improve the value of testing.
- The most important outcome is a practical remediation plan, followed by verification that significant weaknesses have been addressed.
What Is Penetration Testing in 2026?
A penetration test, often called a pen test, is a planned security assessment in which authorised testers attempt to exploit weaknesses in an organisation’s systems within an agreed scope. The aim is not simply to produce a list of possible vulnerabilities. It is to understand which weaknesses could be exploited, how they might be combined, and what the business consequences could be.
Depending on the agreed scope, testers may examine internet-facing servers, corporate networks, web applications, APIs, cloud configurations or other technology assets. Testing should be carried out with written permission, clear boundaries and a plan for handling any significant findings safely. For a general technical introduction, see IBM’s explanation of penetration testing.
For an introductory overview, you can also watch the video below.
Why Regular Testing Matters
Businesses change their technology frequently: software is updated, new services are introduced, staff access changes and systems move into the cloud. Each change can create new risks. Penetration testing provides a structured way to assess important systems and understand how a real attacker might take advantage of a weakness.
Testing may also support an organisation’s wider security and compliance programme. GDPR Article 32 refers to appropriate measures and a process for regularly testing and evaluating security, while NIS2 establishes cybersecurity risk-management obligations for organisations within its scope. Neither should be described as requiring the same penetration-testing schedule for every Irish business. The right programme depends on your systems, risk exposure, contracts and applicable obligations.
Manual and Automated Testing
Automated tools are useful for identifying known weaknesses across large numbers of systems. Experienced testers add context: they can assess whether a reported vulnerability is exploitable, investigate weaknesses in authentication or business logic, and show how several seemingly minor issues could combine into a serious risk. An effective security programme can use both methods.
Types of Penetration Testing Explained
The best type of test depends on the systems you need to protect and the questions you want answered. A business with a public e-commerce website may have very different priorities from one with a large internal network or several cloud-based business applications.
External Penetration Testing
External testing examines systems exposed to the internet, such as public-facing servers, remote access services and other agreed network entry points. It helps assess what an attacker without internal access might discover or exploit.
Internal Penetration Testing
Internal testing examines what could happen if an attacker, compromised account or other threat already had a foothold inside the organisation. It can reveal excessive access privileges, weak network segmentation and opportunities to move between systems.
Network and Infrastructure Testing
Network testing can cover firewalls, server configurations, wireless networks, identity controls and segmentation between systems. Where relevant, the assessment can consider risks in remote working and hybrid infrastructure. See our related guide to network security for Dublin businesses.
Web Application and API Security
Websites, customer portals and APIs can expose business-critical data and functions. Testing may examine authentication, access controls, input validation, session management and business logic. The OWASP Top 10 provides a useful reference for common categories of web application security risk.
Cloud and Microsoft 365 Environments
Cloud security assessments may focus on identity and access management, externally exposed services, configurations and permissions. Testing cloud platforms must follow the provider’s current policies and the organisation’s agreed rules of engagement. A penetration test is not a substitute for continuous monitoring or routine security configuration reviews.
Human factors matter too. Phishing simulations and cyber security awareness training can complement technical testing, although they should be scoped and reported as distinct activities.
Penetration Testing vs. Vulnerability Scanning: Choosing the Right Depth
These two services are often confused, but they answer different questions. A vulnerability scan helps identify potential weaknesses, often using automated checks. A penetration test examines whether agreed weaknesses can actually be exploited and what that exploitation could mean for the organisation.
When Vulnerability Scanning Is Useful
- Checking systems regularly for known vulnerabilities and missing security updates.
- Monitoring changes in a network or cloud environment between detailed assessments.
- Helping IT teams prioritise routine remediation work across many assets.
When a Penetration Test Is Appropriate
- Before a major application launch or after significant infrastructure changes.
- When a business needs deeper assurance about a high-value or internet-facing system.
- When contracts, regulators or risk assessments call for independent security validation.
- After significant remediation, where a targeted retest can confirm that exploitable issues have been addressed.
A scanner may report that a vulnerability is present; a penetration tester can investigate exploitability within the agreed boundaries. Neither approach eliminates risk, and neither should be treated as a guarantee that a system is secure.
How to Organise a Successful Penetration Test: A Five-Step Roadmap
Step 1: Define the Objectives and Scope
Identify the systems, applications, environments and business risks you want to assess. Agree which assets are in scope, which are excluded and whether the test will be external, internal, authenticated or unauthenticated. This prevents misunderstandings and helps ensure the results answer the right questions.
Step 2: Agree Authorisation and Rules of Engagement
Obtain written permission from the appropriate asset owners and document how testing will be conducted. Agree testing windows, emergency contacts, prohibited techniques, data-handling requirements and how critical findings will be escalated. Even controlled testing can carry some operational risk, which should be managed in advance.
Step 3: Conduct the Assessment
Testers gather information, identify potential vulnerabilities, validate findings and—where explicitly authorised—demonstrate the practical impact of exploitation. The methods used depend on the scope and may include manual techniques supported by specialist tools. Testing should be documented so significant results can be understood and reproduced safely.
Step 4: Review the Report and Remediate
The findings report should explain the affected assets, the risks identified, evidence supporting those findings and recommended corrective actions. Prioritise work according to severity, exploitability and business impact. Some issues may require configuration changes, software updates, improved access controls or longer-term architectural work.
Step 5: Retest and Plan Ongoing Assurance
After remediation, arrange targeted retesting of significant findings to confirm that the fixes are effective. Feed the results into your wider security programme, including vulnerability management, monitoring, staff awareness and future testing plans. The frequency of further penetration tests should reflect changes to your environment and your organisation’s risk profile.
How Landmark Can Help Strengthen Your Security
Landmark Technologies works with Irish organisations to identify cybersecurity risks and improve the protection of their systems and data. Penetration testing can provide valuable evidence of where security controls need attention, while wider cybersecurity services help organisations address and manage risks over time.
If your organisation is considering a security assessment, explore Landmark’s Penetration Testing services. The service page explains how to discuss your requirements and the next steps for assessing your environment.
A Broader Approach to Cyber Resilience
Penetration testing is one part of a wider security programme. Depending on your needs, that programme may include vulnerability scanning, managed detection and response, network security, security awareness training and incident response planning. These activities support different stages of identifying, reducing and responding to risk.
Ready to Discuss Your Requirements?
Before requesting a test, it helps to know which systems are most important to your business, any relevant compliance or customer requirements, and whether you’re preparing for a specific change or reviewing your overall security posture.
Explore Landmark’s Penetration Testing services or contact the Landmark team to discuss your requirements.
Building a More Resilient Business
A penetration test gives decision-makers a clearer view of how security weaknesses could affect the business. Its value lies in helping teams prioritise meaningful improvements—not in achieving a perfect score or producing a report that is never acted upon.
For Irish businesses, a sensible approach combines testing at appropriate intervals with regular vulnerability management, effective access controls, staff awareness and a clear response plan. The result is a more informed and manageable approach to cybersecurity risk.
Frequently Asked Questions
How much does penetration testing cost for an Irish SME?
Costs depend on the scope, complexity, testing method and time required. A single web application assessment can differ considerably from a wider internal network and cloud engagement. Ask for a scope-based proposal rather than relying on a generic price range.
Will penetration testing cause downtime?
Professional testing is planned to minimise disruption, but no credible provider can guarantee zero operational risk. Agree the test window, exclusions, escalation process and any sensitive systems before work begins.
How often should a business commission a penetration test?
The appropriate interval depends on risk, contractual or regulatory obligations and how frequently your systems change. Many organisations schedule periodic assessments and additional tests after major changes or significant security incidents.
What is the difference between internal and external penetration testing?
External testing looks at agreed systems accessible from outside the organisation. Internal testing examines what could happen if someone already had a foothold within the network. Together, they can provide a broader view of exposure.
Is penetration testing legally required under GDPR or NIS2?
There is no single blanket rule requiring every Irish business to perform the same penetration test every year. GDPR Article 32 calls for security measures appropriate to risk and for regular testing and evaluation. NIS2-related obligations depend on whether an organisation falls within scope and on applicable national requirements. Obtain legal or compliance advice about your specific duties.
What should a penetration-testing report contain?
A useful report should include an executive summary, the scope and methodology, identified vulnerabilities, supporting evidence, risk ratings, likely business impact and prioritised recommendations. A technical appendix and a remediation or retesting plan are also valuable.
Do all findings need to be fixed immediately?
Not every finding carries the same risk. Prioritise issues according to their severity, exploitability, affected systems and business impact, and agree owners and deadlines for remediation. Critical findings may require immediate action.
Can we test our cloud environment?
Yes, within an agreed scope and subject to the relevant cloud provider’s testing rules. Some techniques and services may be restricted, so confirm permissions and rules of engagement before starting.