The 3 Approaches to Penetration Testing: Black, Grey and White Box Testing
Cyberlogic Insights

The 3 Approaches to Penetration Testing: Black, Grey and White Box Testing

Discover the differences between these three penetration testing approaches to improve your organisation's cyber security.

In our previous article, A Comprehensive Guide to Penetration Testing, we took you through a detailed exploration of the specific six-phase approach to penetration testing followed by our Red Team and unpacked what goes into each stage. As a reminder, penetration testing is a crucial aspect of cyber security as it helps organisations assess their security posture and identify and prioritise vulnerabilities for remediation. There are different approaches to penetration testing, including black box, white box, and grey box testing. Each type offers a unique perspective and evaluation of an organisation's security posture. 

In this article, we'll look at how each of these methods work and explore their differences and benefits to help you determine which approach best meets your organisation's security needs. Understanding these differences is important for organisations to improve their cyber security and stay one step ahead of cyber threats. 

Black Box Pen Testing: Exploiting the Vulnerabilities 

Black box penetration testing is commonly known as the most challenging and realistic form of pen testing as it provides a realistic assessment of the organisation's security posture by mimicking the actions and tactics of real-world cyber-attacks. As the name suggests, this method involves assessing the security of an IT environment or system without any prior knowledge of its inner workings. The pen testers rely solely on external reconnaissance and vulnerability scanning to identify weaknesses and potential points of entry.  

Black box pen testing is an ideal approach for organisations that want to better understand how their security measures will hold up against an attacker with limited knowledge. 

White Box Pen Testing: Identifying the Weaknesses 

Unlike the previous approach, White Box testing involves testers having full knowledge of the organisation's systems and infrastructure. This approach allows for a more thorough examination of security controls, providing insights into the internal workings of the systems. During white box testing, the testers can analyse the organisation's network architecture, source code, and system configurations. This type of testing helps identify vulnerabilities that may not be visible from an external perspective and allows organisations to holistically strengthen their security measures. 

Grey Box Pen Testing: Evaluating the Defences   

While Black Box testing assesses the target system without internal knowledge, and White Box testing, with full access to internal data, evaluates security from both an external and internal perspective, Grey Box testing uses a combination of these approaches. It offers a realistic assessment of how an organisation's security measures would hold up against both external and internal threats. By conducting grey box testing, organisations can effectively identify and mitigate vulnerabilities that may arise from insider threats and compromised internal systems, as well as threats from external attacks, strengthening their overall security posture. 

Choosing the Right Approach for Your Organisation 

Once you have a clear view of how you want to test your security posture, it’s important to understand the pros and cons of the different approaches as outlined in the table below. This ensures you use the methodology best aligned to your needs, resulting in the maximum value from your penetration testing investment:  






Black Box Testing 

  • Mimics real-world attack scenarios. 
  • Uncovers blind spots that might evade detection. 
  • Assesses security from an external viewpoint. 
  • Emulates the perspective of an uninformed attacker. 
  • Limited by lack of internal information and view into internal workings and therefore may overlook internal vulnerabilities. 
  • May require advanced reconnaissance for effective testing. 
  • Testing may be limited to surface-level vulnerabilities 



White Box Testing 


  • Provides comprehensive internal insights. 
  • Identifies intricate internal vulnerabilities. 
  • Allows for targeted remediation strategies. 
  • Enables precise vulnerability assessment. 
  • Relies heavily on system familiarity. 
  • May miss external facing vulnerabilities. 
  • May not reflect real-world attack scenarios. 
  • May be time-consuming and resource-intensive. 
  • Scope may be restricted to known systems and assets. 


Grey Box Testing 


  • Strikes a balance between external and internal perspectives, providing insights into both. 
  • Offers a nuanced evaluation of security posture.  
  • Achieving a balanced assessment is a complex task. 
  • Potential for overlooking certain types of vulnerabilities, such as weaknesses in specific network segments or protocols. 
  • Requires skilled testers to navigate complexities. 


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Black box, white box, and grey box testing each offer unique perspectives and evaluations, allowing organisations to take a holistic approach to security. The value of human intervention in this process cannot be overstated. Unlike automated scans or vulnerability assessments, the strategic implementation of penetration testing, with the help of experienced professionals simulating real-world cyber-attack scenarios, provides a more comprehensive view of vulnerabilities, and helps organisations strengthen their defences more effectively.  

When deciding which approach is best for a client, our team considers the scope of the penetration test, the client’s specific needs, and their current cyber security maturity level. This enables them to determine the right approach for each client. In some cases, the team will conduct a hybrid penetration test, starting with a black box approach and then moving to a grey box approach. In this way, we are able to tailor the approach to the client's needs, goals, and budget. 

At Cyberlogic, we offer a comprehensive suite of cyber security solutions, which includes penetration testing, vulnerability management, and remediation solutions. To find out more, visit the Security Solutions page on our website or reach out to us at 

Read the previous post in the series.

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