Every company operating digital infrastructure, web applications or storing sensitive data faces the constant threat of a cyber attack. The question today is not whether your company will be targeted, but when. Penetration testing is one of the most effective tools to assess the state of your defences before a real attacker does.
In this article we explain exactly what penetration testing is, the types that exist, how the entire process works and what your company will gain from it.
What is penetration testing?
Penetration testing (shortened to pentest) is an authorised, controlled and methodical attempt to breach an information system, network or application. It is carried out by experienced security specialists, ethical hackers, who use the same techniques, tools and approaches as real attackers. The difference lies in the fact that they have the explicit consent of the system owner and their aim is to identify security weaknesses and recommend their remediation, not to exploit them.
A pentest is not the same as an automated vulnerability scan, which mechanically scans a system and compares it against a database of known vulnerabilities. A human tester combines automated tools with their own judgement, creativity and knowledge of current attacker techniques. This allows them to uncover complex vulnerabilities, logical errors in applications or incorrect configurations that automated tools would miss.
Why is a penetration test essential?
Companies invest in firewalls, antivirus software, encryption and other security measures. However, even well-designed defences can have gaps, in configuration, code, processes or the human factor. Penetration testing reveals these gaps in a controlled environment where damage is minimal, resulting in a report with specific recommendations.
Additionally, a number of regulatory frameworks: including NIS2PCI DSS or ISO 27001 - directly require or recommend regular penetration testing as part of cybersecurity management. If your company processes payment cards or personal data on a larger scale, pentesting ceases to be merely a recommendation and becomes a mandatory requirement.
Types of penetration testing
Penetration testing is classified according to the level of knowledge the tester has about the system and what is being tested. The right choice depends on your objectives and the current security status.
According to knowledge of the environment: Black, Grey and White Box
- Black Box (black box): The tester does not know the system's internal architecture. They simulate an external attacker who knows only what is publicly available about the target company. This is the most realistic scenario, but also the most expensive and time-consuming, as reconnaissance takes longer.
- Grey Box (grey cabinet): The tester has partial information at their disposal, for example, standard user login credentials or a network diagram. They simulate an attack by an insider or an attacker who has already gained access to part of the system. This approach combines the realism of black-box testing with the efficiency of white-box testing.
- White Box (white enclosure): The tester receives full documentation, source code, architectural diagrams, and access credentials. This serves for an in-depth audit of code and configuration security. It is the most effective approach in terms of coverage but less realistic from the perspective of simulating an attack.
According to the subject of testing
- External penetration test: It focuses on elements accessible from the internet, websites, VPN gateways, mail servers, cloud services. It tests what an attacker can see from outside and whether they can penetrate the internal network.
- Internal penetration test: Simulates an attack from within the organisation, whether it involves a compromised employee, an attacker who has physically entered the office, or malware in the internal network. It reveals opportunities for lateral movement and privilege escalation.
- Web application testing: In-depth security audit of a specific web or mobile application. The tester looks for vulnerabilities from the OWASP Top 10 category - SQL injection, Cross-Site Scripting (XSS), flawed authentication, exposure of sensitive data and others.
- Social engineering: Tests the human factor, how employees react to phishing emails, fraudulent phone calls or attempts at physical entry into the building. More on this topic can be found in our article about phishing simulations for companies.
How does penetration testing proceed?
Professional penetration testing is not a chaotic attack. It follows a methodology and proceeds through defined phases that ensure coverage and reproducibility of results.
Phase 1: Defining the scope and rules
Before commencement, a contract defining the scope of work is signed. scope - specifying what the tester is permitted to test and what is prohibited. The systems to be tested, time windows, contact persons for incidents, and forbidden techniques (such as tests that could cause a production system outage) are defined. Without a clearly defined scope, a pentest cannot be conducted ethically or safely.
Phase 2: Reconnaissance Survey
The tester gathers information about the target using both passive and active methods. Passive reconnaissance involves analysing publicly available sources, WHOIS records, subdomains, job advertisements, and social media. Active reconnaissance then includes port scanning, identifying running services, and their versions.
Phase 3: Vulnerability Identification
Based on the survey, the tester identifies potential entry points and looks for specific vulnerabilities, outdated software, weak configurations, missing security patches or logical errors in the application.
Phase 4: Exploitation
The tester attempts to actually exploit the discovered vulnerabilities, by penetrating the system, escalating privileges and gaining access to sensitive data. The aim is not to cause damage but to demonstrate that the vulnerability is genuinely exploitable, not merely theoretical.
Phase 5: Documentation and Reporting
The result of the pentests is a detailed report addressed to two groups of readers: the technical team (with a detailed description of vulnerabilities, steps for reproduction and recommendations for remediation) and company management (with an overview of risks, business impact and priorities). Each vulnerability is rated according to severity, critical, high, medium, low.
What does a company gain from penetration testing and how often should it be carried out?
The output of penetration testing is not just a list of errors. The company gains an overview of its actual security status, not the one it assumes. It receives a prioritised remediation plan that enables effective resource allocation, fixing the most critical issues first.
A penetration test also serves as proof to business partners, insurers or regulators that the company takes cybersecurity seriously. In the context of the NIS2 Directive, documentation from penetration tests can form part of the mandatory record of security measures.
Recommended frequency of penetration tests
- At least once a year for all companies with relevant digital infrastructure.
- After every major change - deployment of a new application, migration to the cloud, network restructuring.
- Following a security incident - to verify that the attacker has not left any backdoors and that the root cause has been truly eliminated.
- Ongoing through bug bounty programs or continuous testing of critical systems.
Companies subject to NIS2 should include penetration testing in their cybersecurity management plan as a regular, recurring activity: not as a one-off project.
If you are unsure where to begin or need to design the scope of your company's first penetration test, contact our specialists at secureon.czWe offer a free initial consultation to determine the most suitable type of testing for you and identify your greatest risks.