What Are Penetration Tests? The Basics of Pentesting in 2025
Learn the fundamentals of penetration testing - what pentesting is, what its types are and why it is essential for the security of every organization in 2025.
A penetration test is a controlled simulation of a cyberattack
Penetration testing (pentesting) is an authorized simulation of a cyberattack carried out by security experts in order to identify vulnerabilities in IT systems before real cybercriminals exploit them.
What is penetration testing?
Pentesting is a systematic process of testing security by simulating a real attack on an organization's information systems. Unlike automated vulnerability scans, penetration testing requires human creativity and the pentester's experience.
Key characteristics of professional penetration testing:
- Authorized and legal - conducted on the basis of a written agreement
- Controlled - with clear time and scope boundaries
- Methodical - based on recognized industry standards
- Documented - with a detailed report and recommendations
Pentesting vs vulnerability scanning
Whereas vulnerability scanning is the automated identification of known issues, pentesting goes much further:
- Explores identified vulnerabilities - verifies their real impact
- Combines different vulnerabilities - builds attack chains
- Tests business logic - finds flaws that automated tools will not detect
- Simulates a real attacker - uses creativity and experience
Types of penetration tests
Depending on the level of knowledge made available to the pentester, we distinguish three main approaches:
Black-box
Under the Black-box methodology, the consultant is not given access to the application or network. The consultant has to carry out reconnaissance in order to obtain the sensitive information needed to proceed further.
This type of testing is the most realistic simulation of a cyberattack. However, it requires a great deal of time and has the highest probability of missing a flaw that exists in the internal part of the network or application.
Pros
- Realistic simulation of an external attack
- Tests the actual perimeter defenses
- Shows what a real attacker sees
Cons
- Time-consuming and expensive
- May miss internal vulnerabilities
- Limited by protective systems
Note! In reality, attackers usually have no time constraints and can spend months developing an attack plan, waiting for the right opportunity. The fact that a configuration prevents a flaw from being found or exploited does not automatically mean that the flaw does not exist or is actually mitigated.
Gray-box
Under the Gray-box methodology, the consultant is given access to internal information and knowledge, which may be provided in the form of lower levels of access, application logic flow diagrams or network infrastructure maps.
This is a simulation of the actions of a cybercriminal who has already broken through the perimeter and has limited internal access to the network. Having certain preliminary information and lower levels of access allows for a more effective and structured approach.
Pros
- Optimal coverage within a reasonable time
- Focuses on high-risk systems
- Detects vulnerabilities not accessible from the outside
Cons
- Requires cooperation with the IT team
- Less realistic than Black-box
- May miss perimeter configuration issues
This saves time during the reconnaissance phase, allowing consultants to focus their efforts on exploiting potential security flaws in higher-risk systems, instead of trying to discover where those systems might be located.
White-box
Under the White-box methodology, the consultant has full access to all applications and systems subject to the security assessment. The consultant is given high-privilege access to the network and can view the source code.
The goal of White-box testing is to identify potential weaknesses in various areas, such as logical weaknesses, inadequate security configurations, poorly written programming code and the absence of defensive systems.
Pros
- The most comprehensive testing
- Detects logical vulnerabilities in the code
- Identifies configuration errors
Cons
- Very time-consuming and expensive
- Requires high qualifications
- Less realistic than a real attack
This type of assessment is more comprehensive, because both internal and external weaknesses are evaluated from a "behind the scenes" point of view that is inaccessible to typical attackers. Due to the need to review every aspect of the system in detail, White-box testing is usually reserved for high-risk systems or those that process sensitive data.
Penetration testing methodologies
Professional penetration testing relies on proven methodologies that ensure a systematic and comprehensive approach:
OWASP - Web/Mobile Applications
The OWASP Testing Guide is the standard for web and mobile applications. It defines detailed procedures for testing over 200 different aspects of application security.
- OWASP Web Security Testing Guide
- OWASP Mobile Application Security Verification Standard (MASVS)
- Regular updates aligned with new threats
PTES - Comprehensive testing
The Penetration Testing Execution Standard is a comprehensive methodology covering all aspects of penetration testing, from planning to reporting.
- 7 main testing phases
- Detailed guidelines for each stage
- Universal applicability
NIST SP 800-115 - Infrastructure
NIST Special Publication 800-115 focuses on testing network infrastructure and systems. It is particularly valued in the public and corporate sectors.
- Network infrastructure testing
- Compliance with government requirements
- Procedures for critical systems
Choosing the right methodology
The choice of methodology depends on the type of system being tested:
- Web/mobile applications → OWASP Testing Guide
- Network infrastructure → PTES or NIST SP 800-115
- Corporate systems → PTES + elements of NIST
- Compliance (GDPR, PCI DSS) → NIST SP 800-115
Why is penetration testing essential?
It goes beyond automation
Modern systems are too complex for automated tools. Pentesters find vulnerabilities that scanners will not detect:
- Business logic flaws - incorrect processes within applications
- Attack chains - combining several small issues into a serious attack
- Configuration issues - incorrect system settings
- Social engineering - exploiting the human factor
Business value
Average cost of a security breach in 2024: USD 4.45 million (IBM Security Report)
Cost of professional penetration testing: PLN 15,000-50,000
ROI: A single prevented incident covers the cost of years of testing
Compliance requirements
Many legal regulations require regular penetration testing:
- GDPR - Art. 32: testing the effectiveness of technical measures
- PCI DSS - Requirement 11.3: mandatory penetration testing
- ISO 27001 - Control A.18.2.3: testing of technical security measures
- NIS2 Directive - systems testing requirements
Do you need professional penetration testing?
As a certified pentester (OSCP, OSWA), I offer comprehensive tests compliant with the highest industry standards. Get in touch to discuss your organization's security needs.
Book a free consultationSummary
Penetration testing is an investment, not a cost. In a world of growing cyber threats, it is an essential element of every organization's security strategy.
Key takeaways:
- Pentesting goes beyond automation - it requires human creativity
- Different methodologies for different systems (OWASP, PTES, NIST)
- The ROI of testing significantly outweighs the cost of carrying it out
- Compliance often requires regular penetration testing
- A proactive approach is the key to effective cybersecurity
Remember: Do not wait for the first security incident. Regularly conducted penetration tests are the best investment in your organization's security.