Penetration Testing (Pen Test): Why Companies Should Regularly Check Their IT Systems for Vulnerabilities
Published: June 2026
Reading time: about 8 minutes
Penetration Testing: Identifying Vulnerabilities Before Attackers Exploit Them
Cyberattacks are among the greatest risks facing businesses today. While firewalls, antivirus software, and modern security solutions are important protective measures, they alone do not guarantee protection against successful attacks. Even a single undetected security vulnerability can be enough to compromise confidential data, disrupt business processes, or cause financial damage.
A professional penetration test (pen test) simulates a realistic cyberattack under controlled conditions. The goal is to identify technical vulnerabilities, assess their actual exploitability, and derive specific measures to improve IT security.
This article explains what a penetration test is, how it works, what benefits it offers, and why regular testing is an essential part of a modern cybersecurity strategy.
What is a penetration test?
A penetration test is a targeted security assessment of IT systems. During the test, experienced IT security experts use the same methods and tools as potential attackers to uncover vulnerabilities in networks, servers, applications, or cloud environments.
Unlike an actual attack, the test is conducted in a controlled, coordinated, and documented manner. The goal is not to damage systems, but to assess their resilience against real-world attack scenarios.
A professional penetration test answers the following questions, among others:
- Can external attackers penetrate the corporate network?
- Are the servers and firewalls configured securely?
- Can user accounts be compromised?
- Are there vulnerabilities in web applications or APIs?
- Can attackers expand their privileges within the network?
- Which security vulnerabilities pose the greatest risk?
Why a Penetration Test Is Important
Many companies rely on firewalls, antivirus software, and automated vulnerability scanners. These technologies are indispensable, but they do not detect every security vulnerability and are often unable to assess whether a detected vulnerability can actually be exploited.
A penetration test goes a crucial step further. It not only examines individual vulnerabilities but also analyzes how different vulnerabilities can be combined. This provides a realistic picture of the actual security situation.
Regular penetration tests help companies
- Identifying security vulnerabilities early on,
- To prevent cyberattacks,
- to prevent economic damage,
- to support regulatory requirements,
- to continuously improve its own IT security strategy.
Real-World Example
A medium-sized company planned to implement a new VPN solution to enable mobile access to the corporate network. A penetration test was conducted before the solution was rolled out.
It turned out that multi-factor authentication had not been enabled as a requirement for one user group. An attacker could have gained access to internal systems using stolen login credentials.
The configuration was adjusted prior to commissioning, and the security vulnerability was addressed.
Result: The penetration test made it possible to eliminate a potential attack vector before it was exploited in a production environment.
Penetration Test or Vulnerability Scan?
These two terms are often confused, but they are clearly different.
| Vulnerability Scan | Penetration Test |
|---|---|
| automated testing | Manual and automated testing |
| detects known vulnerabilities | assesses the actual usability |
| provides extensive lists of results | prioritizes real risks |
| No attack simulation | realistic attack simulation |
| minimal effort | in-depth security analysis |
A vulnerability scan is ideal for regular routine checks. A penetration test, on the other hand, provides a much more comprehensive assessment of the actual security situation.
What types of penetration tests are there?
Depending on the objective, different areas are reviewed.
External Penetration Test
This process examines which systems are accessible from the Internet and whether they can be compromised.
Typical test objects:
- Firewalls
- VPN Access
- Web Server
- Email Systems
- Cloud Services
- Remote Access
The test simulates an external attacker with no internal knowledge.
Internal Penetration Test
This scenario assumes that an attacker is already inside the corporate network—for example, through a compromised user account or an infected device.
Among other things, the following are examined:
- Active Directory
- User Rights
- Windows Server
- Network Segmentation
- File Sharing
- Domain Structures
The focus is on how far an attacker could move within the IT infrastructure.
Web Application Penetration Test
Web applications are among the most common targets of attacks.
For example, the following are tested:
- SQL Injection
- Cross-Site Scripting (XSS)
- Authentication
- Session Management
- Permissions
- APIs
- File Uploads
Cloud Penetration Test
With the increasing use of Microsoft 365, Azure, and AWS, cloud security audits are becoming increasingly important.
The focus here is particularly on the following topics:
- Identity Management
- Roles and Permissions
- Storage Quotas
- Configuration errors
- Multi-factor authentication
- Security Guidelines
How does a penetration test work?
A professional penetration test is conducted in several clearly defined phases.
1. Planning
The objectives, scope, and test limits are defined in collaboration with the company.
The following is defined:
- which systems are being tested,
- which areas are excluded,
- when testing will take place,
- which contacts are available.
2. Gathering Information
The testers collect publicly available and technical information about the target systems.
These include, among other things:
- DNS Information
- Available Services
- Software Versions
- Network Structure
- publicly available information
3. Vulnerability Analysis
Automated tools and manual checks identify potential security vulnerabilities.
4. Attack Simulation
Now we’ll check whether the vulnerabilities we found can actually be exploited.
Work is carried out in a controlled manner at all times to avoid unnecessarily disrupting productive systems.
5. Documentation
Upon completion, companies receive a detailed report.
It contains:
- all identified vulnerabilities,
- a risk assessment,
- Technical details,
- Screenshots,
- specific recommendations for action,
- Prioritizing the measures.
When should a company conduct a penetration test?
A penetration test is particularly recommended:
- before new systems are put into operation,
- following extensive infrastructure changes,
- after a cloud migration,
- prior to audits or certifications,
- following security incidents,
- on a regular basis as part of information security management.
Many companies conduct a penetration test at least once a year.
What are the benefits of a penetration test?
A professional penetration test provides insight into the actual security status of the IT infrastructure.
The most important benefits include:
- Identification of previously unknown vulnerabilities
- Assessment of Real Attack Risks
- Improving IT Resilience
- Support with Compliance Requirements
- better preparation for audits
- Proof for customers, partners, and insurance companies
- Prioritizing Necessary Safety Measures
- greater security for business processes and data
Penetration Testing and NIS2
With the European NIS2 Directive, the requirements for risk management and cybersecurity are increasing for many companies.
Organizations must systematically identify risks, establish appropriate safeguards, and regularly review their effectiveness.
A penetration test is an important tool for this purpose. It reveals whether existing security measures can withstand a realistic attack and helps companies identify technical risks early on and reduce them in a targeted manner.
Common Misconceptions
“We have a firewall. That’s enough.”
A firewall protects only part of the IT infrastructure. As a result, misconfigurations, insecure applications, or compromised user accounts often go undetected.
“Our company is of no interest to hackers.”
Automated attacks constantly scan the Internet for vulnerable systems—regardless of a company’s size or industry.
“Our virus scanner detects attacks.”
Antivirus solutions primarily respond to known threats. A penetration test identifies vulnerabilities even before a potential attack occurs.
Conclusion
A penetration test provides companies with a realistic view of their actual security posture. Rather than relying solely on technical safeguards or automated scans, it reveals which vulnerabilities could actually be exploited.
Regular penetration tests help reduce risks, improve security measures in a targeted manner, and increase resilience to cyberattacks in the long term. They are therefore an essential component of a modern IT security strategy.
Frequently Asked Questions (FAQ)
What is a penetration test?
A penetration test is a controlled security assessment in which IT experts simulate a cyberattack to identify vulnerabilities in systems and applications.
How often should a penetration test be conducted?
At least once a year, as well as after significant changes to the IT infrastructure or the introduction of new applications.
How long does a penetration test take?
Depending on the scope, between one and several days. Complex infrastructures may require a longer testing period.
Is a penetration test dangerous?
No. Professional penetration tests are carefully planned and conducted under controlled conditions to minimize disruption to ongoing operations.
How much does a penetration test cost?
The cost depends on the scope, complexity, and objectives of the test. It is therefore advisable to develop a customized plan.
Do you need a penetration test?
Would you like to know how secure your IT infrastructure really is? A professional penetration test will show you which vulnerabilities could actually be exploited—clearly documented and accompanied by specific recommendations for action.
→ Request a consultation now with no obligation
Sources and Further Information
- Federal Office for Information Security (BSI): IT-Grundschutz Compendium
- Federal Office for Information Security (BSI): Guidance on Penetration Testing
- OWASP Foundation: Web Security Testing Guide (WSTG)
- OWASP Foundation: OWASP Top 10 – https://owasp.org/www-project-top-ten/
- NIST Special Publication 800-115: Technical Guide to Information Security Testing and Assessment
- ENISA (European Union Agency for Cybersecurity): Best Practices for Security Testing
- Directive (EU) 2022/2555 (NIS2 Directive)
