Creating a penetration test for a web application is a complex process requiring technical skills, a rigorous methodology and in-depth knowledge of current IT threats. The process involves simulating real-life attacks on an online application to assess its resistance to cybercriminals and detect vulnerabilities before they are exploited.
What are the foundations of application pentesting?
An application penetration test is based on an offensive approach, inspired by the techniques used by hackers, but carried out within a legal and controlled framework. The idea is to put yourself in the shoes of an external attacker and reproduce realistic scenarios to measure the level of protection offered by the web application.
To be effective, this approach must be based on recognized security benchmarks, such as the OWASP Top 10, which lists the most widespread application vulnerabilities. By adopting this standardized approach, the auditor ensures that all critical vulnerabilities are covered, from code injections to authentication and session management problems.
How do you define your scope and objectives?
Before launching a web application pentest, it is essential to precisely define the scope of the test. This stage identifies the modules, functionalities and environments to be evaluated. It also includes determining the objectives, which can vary according to the context: checking the robustness of a customer portal, analyzing the security of an exposed API, or checking the compliance of an e-commerce service with current regulations.
The clarity of this phase determines the relevance of the results, as a poorly defined perimeter can lead to omissions or unaudited areas, leaving room for undetected flaws.
01 – The reconnaissance and information gathering phase
Once the perimeter has been set, the security tester begins a reconnaissance phase aimed at collecting as much data as possible on the target application. This involves identifying the technologies used, framework versions, associated IP addresses and available services.
Common techniques include directory listing, SSL certificate analysis and HTTP header examination. This information gathering provides a complete map of the attack surface, and prepares the next stages of the audit.
02 – Analysis of potential vulnerabilities
Once the information has been gathered, the web pentest enters the vulnerability assessment phase. Auditors use automated tools to detect known vulnerabilities, but also manual techniques to identify more subtle weaknesses.
SQL injections, XSS vulnerabilities, authentication errors or problems related to the storage of sensitive data are just some of the scenarios tested. The aim of this stage is to identify as many exploitable leads as possible, which will then be verified and confirmed during the exploitation phase.
03 – Exploiting detected faults
This step confirms whether an identified vulnerability can actually be used to compromise the application. For example, the auditor may seek to access sensitive data, modify the application’s behavior or impersonate a user.
This exploitation is carried out in a controlled manner, without causing any damage, but it does demonstrate the potential impact of a successful attack. The assessment of criticality is based on the extent of possible damage and the ease with which the flaw can be exploited.
The importance of reporting and recommendations
The final step is to draw up a detailed report for technical teams and security managers. This document presents all the identified vulnerabilities, their level of seriousness, the associated attack scenarios and, above all, recommendations for correcting them.
This report is a strategic tool, enabling priorities to be prioritized and appropriate action plans to be put in place. It also plays an educational role, making developers aware of the errors to be avoided, and reinforcing the safety culture within the organization.
Tools and techniques used during a web pentest
Auditors have a wide range of tools at their disposal for conducting penetration tests on web applications. Burp Suite and OWASP ZAP intercept and manipulate requests to test the robustness of security mechanisms. Nmap is used to analyze accessible services, while scanners such as Nessus or OpenVAS detect known vulnerabilities. Nikto is also used to identify specific web server vulnerabilities, Gobuster is used to discover hidden directories or files, and OpenVAS completes the analysis with a broader vulnerability detection approach.
However, tools are no substitute for human expertise, as many vulnerabilities can only be identified through contextual analysis and a detailed understanding of the application’s business logic. A combination of automated techniques and manual testing is therefore essential to guarantee a reliable pentest.
The regulatory and strategic benefits of web pentesting
Carrying out an application pentest not only addresses technical concerns, but also regulatory and strategic requirements. The RGPD, for example, requires the implementation of appropriate security measures to protect personal data, and certain international standards such as PCI-DSS or ISO 27001 require regular systems audits.
By conducting penetration tests on their applications, companies demonstrate their commitment to protecting their users, and reinforce their credibility with customers and partners. On a strategic level, this approach helps prevent security incidents, limit financial risks and protect the organization’s reputation.
Do I need to repeat this process regularly?
Web application penetration testing should not be seen as a one-off action, but as an ongoing process. Applications are constantly evolving, with new features added, frameworks updated and new plugins added to the ecosystem.
Each change can introduce new vulnerabilities and alter the attack surface. That’s why it’s essential to renew tests regularly and integrate them into an overall security strategy. This recurrence helps maintain a high level of protection and anticipate emerging threats.