What types of pentests exist? Blackbox, Greybox, Whitebox explained
Blackbox testing mimics an external hacker with no prior knowledge of the system, making it ideal for simulating real-world attacks. Greybox testing, on the other hand, provides partial knowledge of the system internals, perfect for regular security checks. Whitebox testing offers a comprehensive view with full access to source code and architecture, aimed at thorough vulnerability assessments and deep security analysis. Each type serves unique purposes and provides valuable insights depending on the organization's specific security objectives.
The 3 Types of Penetration Tests
Choosing the right pentest type determines efficiency, cost, and results. Understand the differences between Blackbox, Greybox, and Whitebox - and when each approach makes sense.
Blackbox Pentest
Zero Knowledge - Maximum Reality
The tester starts without any information about the target system - just like a real attacker. All information must be gathered through reconnaissance and OSINT. This approach simulates most realistically how a cyberattack unfolds.
No prior knowledge, no credentials, no documentation
External attacker attempting to breach your system from outside
Low to Medium (depending on reconnaissance phase)
Advantages
- Most realistic simulation of an external attack
- No influence from internal knowledge
- Shows what an attacker can really see
Disadvantages
- Complex internal vulnerabilities often overlooked
- Much time spent on reconnaissance instead of testing
- Lower coverage with same budget
When you want to test how well your external attack surface is protected - without insider knowledge.
Greybox Pentest
Limited Knowledge - Maximum Efficiency
The sweet spot for most companies: The tester receives limited access to information (e.g., low-privilege accounts, API documentation, portions of source code). This allows the test to focus on real security vulnerabilities instead of wasting time.
Partial information: user accounts, API schemas, selective documentation
Compromised employee or partner with restricted access
Medium (optimal ratio of time to results)
Advantages
- Best cost-benefit ratio
- Focus on critical business logic flaws
- Realistic simulation of an insider attack
- Higher coverage than blackbox with same budget
Disadvantages
- Not as in-depth as whitebox
- Requires preparation (test accounts, documentation)
In 80% of all cases - when you want maximum security at optimal budget. More on costs
Whitebox Pentest
Full Access - Maximum Depth
The tester receives complete access to all resources: source code, documentation, architecture diagrams, admin access. This approach enables the deepest analysis and finds even hidden vulnerabilities that would be missed with other approaches.
Complete access to source code, documentation, admin accounts
Insider with full access or compliance requirements (ISO 27001, NIS2)
High (comprehensive code and architecture analysis)
Advantages
- Deepest possible security analysis
- Finds complex code vulnerabilities
- Ideal for compliance & certifications
- Architecture and configuration issues are identified
Disadvantages
- Very time-consuming and expensive
- Less realistic (attackers rarely have full access)
- Requires significant preparation from client
For critical systems, compliance evidence, or when source code security must be explicitly verified.
Which Pentest Type Fits My Needs?
Decision guide based on your requirements
Optimal Budget-Value Ratio
You want maximum security at reasonable budget?
Compliance & Certification
You need evidence for ISO 27001, NIS2, or similar standards?
External Attack Simulation
You want to test what a real hacker can see from outside?
Critical Business Logic
You have complex business logic or sensitive data processing?
Regular Security Checks
You want to test continuously without large budget each time?
Source Code Vulnerabilities
You suspect security gaps in the code or architecture?
Still unsure? No problem - we provide free consultation and will find the optimal testing strategy for your company together.
Request Free ConsultationDetailed Comparison of All Pentest Types
The most important differences at a glance - so you can make the right decision.
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Blackbox
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Greybox
Recommended
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Whitebox
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|---|---|---|---|
| Primary Goal | Simulation of a realistic external attack and identification of external vulnerabilities | Efficient identification of critical vulnerabilities with optimal cost-benefit ratio | Comprehensive in-depth analysis of the system and identification of complex internal and external vulnerabilities |
| Available Information | None - no prior knowledge, no credentials, no documentation | Limited - low-privilege accounts, API schemas, selective documentation | Complete - source code, architecture, admin access, full documentation |
| Simulates | External attacker without insider knowledge | Compromised employee or partner with restricted access | Insider with full system access or state-level adversary |
| Time Investment | Low - Medium | Medium | High |
| Cost | $$ - Low | $$$ - Medium | $$$$ - High |
| Coverage Depth |
Superficial Focus on external attack surface |
Medium to High Good balance between breadth and depth |
Very High Comprehensive analysis of all layers |
| Main Advantages |
• Realistic external perspective • No preparation required • Shows public attack surface |
• Best cost-benefit ratio • Finds critical business logic flaws • More efficient than blackbox • Realistic insider scenario |
• Deepest analysis possible • Finds code vulnerabilities • Ideal for compliance • Architecture review included |
| Main Disadvantages |
• Misses complex internal vulnerabilities • Much time for reconnaissance • Lower coverage |
• Not as in-depth as whitebox • Requires preparation |
• Very expensive and time-consuming • Less realistic • High preparation effort |
| Ideal For |
• First pentests • External attack surface • Public web apps |
• Most companies • SaaS platforms • Business-critical apps • Regular testing |
• Critical infrastructure • Compliance requirements • Financial sector • Healthcare |
What do terms like "API Pentest" or "Mobile Pentest" mean?
You often see terms like "API penetration test", "Mobile App Pentest" or "Cloud Pentest". These describe the target system, not the testing methodology. An API pentest can be conducted as blackbox, greybox, or whitebox - depending on how much access you grant the tester.
Example: An "API Pentest" can be a greybox test where the tester receives OpenAPI schemas, or a whitebox test with full access to the backend code. The choice of blackbox/greybox/whitebox is up to you.
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