A penetration test, or pentest (penetration testing), is the most comprehensive security assessment a company can conduct. Rather than waiting to be affected by a cyberattack, it involves allowing security experts ( ethical hackers) to simulate a real attack against your infrastructure, applications, or employees. The objective is clear: to identify and exploit vulnerabilities before criminals can, in order to fix them.
Beyond the Vulnerability Scan
It is crucial not to confuse an automated vulnerability scanner with a real penetration test.
| Characteristic | Vulnerability Scan | Penetration Test (Pentest) |
| Nature of the tool | Automated software (Nessus, Qualys, etc.). | Human action with advanced tools and custom scripts. |
| Objective | List known (CVE) vulnerabilities that have not been patched. | To prove that a vulnerability is exploitable and to measure its real impact. |
| False positives | Frequent. Require expert manual sorting. | Virtually non-existent. Each vulnerability is checked manually. |
| Depth | It stops at simply detecting the vulnerability. | It goes as far as intrusion, privilege escalation, and exfiltration. |
The 3 Approaches to Pentesting
Depending on your objectives and the maturity of your cybersecurity, the level of information provided to auditors defines the type of test:
- The Black Box: The auditor has no prior information other than the company name. They simulate an opportunistic attack from the outside. This is the most realistic approach to testing the robustness of the network's exposed perimeter.
- The Grey Box: The ethical hacker receives partial information, such as a standard user account or access to the guest Wi-Fi network. This test simulates an attack originating from a malicious employee, a business partner, or a hacker who has already compromised a basic account.
- The White Box: Auditors have full access (application source code, architecture diagrams, administrator access). The goal is absolute thoroughness to detect complex logical flaws, often used before the production deployment of critical applications.
Scope of Action: What are we testing?
A penetration test can target different layers of your organization:
- External infrastructure: Firewalls, web servers, VPN gateways, cloud messaging.
- Internal infrastructure: Active Directory, domain controllers, file servers, virtual local area network (VLAN) segmentation.
- Web and Mobile Applications: Search for injection vulnerabilities (SQL, XSS), authentication flaws or manipulation of business logic (OWASP Top 10).
- Social Engineering: Highly targeted phishing campaigns (spear-phishing), phone calls (vishing) or attempts at physical intrusion into premises.
The Standardized Methodology
A professional penetration test cannot be improvised. It methodically follows strict frameworks (such as the international PTES standard):
- Reconnaissance (OSINT): Collection of public information about the company, its employees, its IP addresses and its technologies.
- Modeling and Scanning: Network mapping and identification of potential entry points.
- Exploitation: Attempting penetration via discovered vulnerabilities (exploiting software flaws, bypassing authentication).
- Post-Exploitation: Once inside, the auditor attempts to maintain access, pivot to other machines (lateral movement), and become a domain administrator to prove maximum impact.
- Report and Remediation: Delivery of a detailed report classifying risks by criticality, accompanied by a precise technical action plan to correct each vulnerability.
In an increasingly stringent regulatory environment, particularly with the NIS2 directive requiring regular security audits, penetration testing has become a strategic necessity. At Onetosecure, we orchestrate and support these security assessments from start to finish. From defining the scope (cloud infrastructure, local networks, business applications) to assisting with the remediation of identified vulnerabilities, we guarantee that your security posture can withstand the test of real threats.