Your software is the backbone of your business. Customers log in, employees process data, and links with partners run day and night. But what if there’s a vulnerability in that software that you don’t know about, and an attacker does? That’s exactly where an application pen test comes in: a targeted test in which ethical hackers attack your application as if they were real criminals, to find and fix vulnerabilities before it’s too late.
According to the Cyber Survey Belgium 2025, half of Belgian organizations reported an increase in attacks, and one in six experienced a successful incident. Supply chain attacks, in which attackers penetrate through vendor software, already affected 38% of Belgian companies. Your application is not just a tool, it’s a potential entry point for attackers.
What exactly is an application pentest?
An application pen test (or application penetration test) is a controlled attack on your software by certified ethical hackers. The goal: detect vulnerabilities in your web application, mobile app, API or desktop software before real attackers do.
The difference with an automated vulnerability scan is important. A scan runs down a checklist of known vulnerabilities. Useful as a starting point, but limited. An application pen test goes much further: the tester thinks like an attacker, combines smaller weaknesses into a serious attack chain, and tests your application’s unique business logic. A scan finds the front door open. A pen test finds that the back door, the kitchen window AND the garage flap combine to form an intrusion route.
Specifically, an application pen test tests for things like unauthorized access to other users’ data, manipulation of payment flows or ordering processes, reading sensitive data through API links, and bypassing login mechanisms or session security.
Three approaches: black box, gray box and white box
Not every application pentest proceeds in the same way. Depending on the goal, you and your security partner choose the right approach.
In a black box test, the tester gets no prior knowledge of the application. This simulates an outside attacker starting from scratch. You get a realistic picture of what an outside hacker can accomplish.
In a gray box test, the tester has limited access, such as an ordinary user account. This is the most commonly used approach for enterprise applications because it shows what a logged-in user (or a hacked account) can do. Consider viewing other clients’ data, increasing one’s own privileges, or manipulating processes.
In a white box test, the tester gets full access to the source code and architecture documentation. This provides the most thorough analysis and is ideal for mission-critical software or applications that process sensitive data.
Which approach fits best depends on your situation. A SaaS platform that processes customer data requires a different test than an in-house inventory management tool.
The OWASP Top 10: the risks that threaten your application
Every professional application pen test at least on the OWASP Top 10, the internationally recognized list of the most critical Web application security threats. An updated version was released in 2025 that reflects current threats. Some key risks:
Broken Access Control has been number one for years, meaning users can do things they are not authorized to do: view other clients’ data, perform admin functions, or download files not intended for them. OWASP data shows that about 3.7% of all applications tested found at least one access control problem. In practice, almost every security test does find some form of poor access control.
Security Misconfiguration rose from spot 5 to spot 2. Think default passwords not changed, redundant services still running, or cloud storage accidentally being publicly accessible. As software becomes more complex, configuration errors increase.
Software Supply Chain Failures is new to the top 10. This is about vulnerabilities in the libraries, frameworks and tools your developers use. One insecure component in your software supply chain can undermine the entire application. This risk is especially relevant for Belgian companies: 38% have already been affected by vendor-based attacks.
Injection, including SQL injection and cross-site scripting (XSS), dropped from spot 3 to 5 but remains a common problem. Injection attacks involve malicious code being sent to your application via input fields.
An application pen test not only tests your software against this list, but also looks at specific business logic that may fall outside standard frameworks.
How does an application pen test work in practice?
A professional application pentest follows a structured process. Not a random search, but a methodical approach that builds on recognized standards.
Step 1: Scoping and preparation. Together you determine which applications, environments and functionalities will be tested. Clear agreements are made about the test window, emergency contacts and what is and is not allowed. These “Rules of Engagement” form the basis for a safe test without disrupting your business operations.
Step 2: Exploration and mapping. The tester maps the application: what pages, features, API endpoints and user roles exist? What technologies are being used? This phase resembles the work of a burglar who looks around before striking.
Step 3: Vulnerability Analysis. Using a combination of automated tools and manual examination, the tester detects vulnerabilities. This is where human expertise makes the difference: an experienced pentester recognizes patterns and logical flaws that scanners miss.
Step 4: Exploitation. The vulnerabilities found are actually exploited to demonstrate impact. Not to do damage, but to show with evidence what a real attacker could achieve. Could the tester see customer data? Take over an administrator account? Manipulate payments?
Step 5: Reporting and discussion. The result is a clear report with each finding linked to a risk level and concrete recommendations. Not a thick report that gathers dust, but a usable roadmap with quick wins and structural improvements. At Cyberplan, the results are personally explained to both the IT team and management in understandable language.
When does your company need an application pen test?
An application pen test is not just for big tech companies. You’ll benefit if your software processes customer or personal data, your application handles financial transactions, customers or partners have security requirements (think ISO 27001, SOC 2 or a Vendor Risk Assessment), you’re looking to launch a new application or major update, your company is under NIS2 or DORA and you need to demonstrate compliance, or you’re developing software that falls under the Cyber Resilience Act (CRA).
The latter in particular is becoming increasingly relevant. The CRA requires manufacturers of digital products to incorporate security structurally. The first reporting requirements will start in September 2026. An application pen test will then no longer be a “nice to have,” but a demonstrable step toward compliance.
Application pentest and compliance: NIS2, DORA and CRA
Belgian regulations around cybersecurity are becoming increasingly stringent. NIS2 has been transposed into Belgian law since Oct. 18, 2024, and obliges essential and important entities to engage in structural risk management, including system testing. An application pen test is a concrete implementation of that obligation.
For financial institutions and their IT vendors, DORA imposes specific requirements for periodic application testing, including advanced threat-led penetration testing (TLPT) every three years.
And the Cyber Resilience Act focuses on the security of digital products throughout their life cycle. Belgian software companies bringing products to the European market must demonstrate that security is built in from design.
In all these cases, an application pen test provides tangible proof that you are taking responsibility.
Frequently asked questions about application pentesting
What does an application pen test cost?
The price depends on the size and complexity of the application. For an average web application of an SME, you can count on an investment of several thousand euros. Through the VLAIO SME portfolio, small enterprises receive a 30% subsidy and medium-sized enterprises a 20% subsidy on cybersecurity advice, significantly reducing the net cost.
How long does an application pen test take?
A typical application pen test takes 5 to 15 business days, depending on the size of the application and the approach taken (black, gray or white box). Preparation and reporting are on top of that.
Does an application pen test disrupt my application?
No, provided the test is conducted professionally. Clear agreements are made in advance about the test window and limits. An experienced team tests in such a way that your users do not notice anything.
How often should I have an application pen test performed?
At least annually, and with every major update or change to your application. Under NIS2 and DORA, a higher frequency may be required. Software changes constantly, and so do vulnerabilities.
What is the difference between a vulnerability scan and an application pentest?
A vulnerability scan is automated and checks for known weaknesses. An application pentest is performed by an ethical hacker who also detects unknown vulnerabilities, logical flaws and complex attack chains. The scan is an X-ray; the pentest is a full medical examination.
Is an application pen test mandatory under NIS2?
NIS2 requires organizations to take appropriate technical measures for risk management, including testing systems. An application pen test is one of the most effective ways to meet that obligation.
Protect your software with the right expertise
Vulnerabilities in your application don’t have to be found on your own. Cyberplan combines a team of 22 certified ethical hackers (OSCP, CEH, CISSP) with an approach that translates results into understandable insights for both your IT team and your management.
Whether you need to have an existing Web application tested, demonstrate compliance for NIS2 or DORA, or build security into your development process, Cyberplan thinks with you as a partner, not an outsider.
Good to know: through the VLAIO kmo-portefeuille you can apply for a subsidy on cybersecurity advice as an SME, and through the Cybersecurity Improvement Projects up to 50% support is possible on guidance trajectories. This makes professional application security accessible to medium-sized companies as well.
Wondering what an application pentest can do for your software? Book a no-obligation consultation with one of our specialists.
