Black-Box Penetration Testing in Cybersecurity

Black-Box Tests are a software testing method that focuses on the functionality and behavior of an application without knowing how it works internally. With this testing approach, the goal is not to find bugs but rather to understand how the application works and its capabilities.

This article discusses how black-box testing identifies security gaps and prevents potential vulnerabilities for startup and enterprise-level organizations. We also delve into its types of pentest techniques and address commonly asked questions.

What is black-box testing, and why is it important for your business?

Black-box security testing is a software testing method used to examine the functionality of an application with limited knowledge of its architecture or internal processes. This approach, also known as closed-box testing, relies on outputs from implementing specific execution conditions on selected inputs to observe the application’s functionality.

For example, a black-box penetration test helps organizations reduce their attack surface by uncovering common vulnerabilities undetected by the development team during code testing. QA teams can also build test cases for specific usage scenarios, which provide application performance information from a user’s point of view. 

Additionally, you can learn more about the latest cybersecurity trends for businesses.

When to Implement Black Box Scanning?

Black box testing examines various aspects of an application’s functionality. As a result, black-box testing techniques are applicable across multiple phases of the SDLC, including:

  • Integration testing for new features during deployments and rollouts
  • In production, to understand application usability and the user experience
  • During acceptance testing, to understand the effects of third-party solutions on application security
  • During quality assurance, to ensure the application works as expected before deployment
Black-box testing visualized - Crashtest Security

Types of Tests in Black Box  Testing

A black-box penetration test can be categorized primarily into three types of testing. These are:

1. Functional testing

A form of closed-box testing examines how the software performs against specific functional requirements. The tests check the software’s mainline functions (user interface, databases, security, etc.) by supplying a particular input and comparing its actual output with the expected behavior. An ethical hacker develops functional test cases based on business scenarios and other applicable requirements to determine the application’s conformance to SLAs in such a testing approach. These cases can either be automated or achieved by manual penetration testing, and they typically focus on the system’s accessibility and error conditions. 

2. Non-functional Testing

Non-functional testing examines the non-functional requirements of the application, including performance, reliability, and usability, among others. These parameters are commonly used to measure the application’s ability to run effectively within its deployment environment. Therefore, a non-functional test provides detailed information on the application and tech stack’s behavior, helping avoid runtime security vulnerabilities. Aspects covered by this type of testing include:

  • Software performance testing
  • Load testing
  • Stress testing
  • Volume testing
  • Compliance testing
  • Portability testing
  • Configuration testing
  • Recovery testing

3. Regression Testing

Regression testing is a black-box security testing method used to validate whether a recent update has affected the application’s existing functionality. The approach involves a partial dynamic analysis test that re-executes test cases on existing features to ensure new changes do not incur unwanted side effects. Regression tests are mainly used when a new version of source code has been deployed or when segments of code fixes have been released. Acting as a foundation for the acceptance testing approach, regression testing can be automated using tools that build test libraries out of varying combinations of previous test cases, thereby reducing the manual efforts of QA teams.

Black Box Pentest Techniques 

Testers use several black-box pentest techniques to design test cases for varying requirement specifications. These black-box testing types include:

Equivalence Partitioning

A black-box security testing method derives test cases from data classes within the input domain. A typical test case divides the input domain into equivalent classes/partitions and then evaluates each class for specified input conditions. The software requirements and specifications additionally define the equivalence partitions. Test cases also validate whether the values of a partition behave the same as other equal partitions, thus determining valid or invalid inputs

Boundary Value Analysis (BVA)

This black-box pentesting technique uses boundary values (values at the lower and upper limits of variables) to identify the source of input errors. Using this technique, testers design test cases to examine application functionality at the beginning and end of each partition using test data. Boundary value analysis is commonly used to identify system errors at the extreme ends of the input domain and only applies to test cases where the partitions are ordered sequentially or numerically.

State Transition Testing

A black-box penetration testing technique is used to observe how the application behaves under a sequence of different input conditions. Testers provide both negative and positive input values to the application server to record the valid and invalid state transitions. These tests are most appropriate when determining an operation’s dependencies on past values. This technique also tests real-time systems with multiple states, transition events, and associated conditions.

Decision Table Testing

A systematic closed-box testing approach that tabulates input combinations and their respective system behavior to help evaluate the combinations of input data the application can handle. The decision table correlates inputs versus the rules, test cases, or conditions to map cause-and-effect relationships to form the foundation of structural testing.  


With an error-guessing mechanism, black-box penetration testers rely on their expertise to infer sources of issues within the application. This level of software testing is unstructured since it does not follow any specific rules/conventions. A testing team develops test cases using this approach’s experience with similar performance requirements and software vulnerabilities. 

Black-Box Testing Video Explanation

Everything about black box testing is explained in this short video.

Frequently Asked Questions

Some of the most effective application security tools include:

Crashtest Security Suite

Crashtest Security Suite integrates with most modern development stacks without requiring testing teams to worry about the underlying programming language and application logic. The platform establishes a continuous testing process that includes automated vulnerability scanning to help spot potential security issues before attack vectors exploit them.

Crashtest Security’s vulnerability scanner benchmarks the security scans against the OWASP Top 10 to ensure robust security control with low false positives and negatives.


An AI-powered test automation platform simplifies black-box penetration testing using visual snapshots. The Applitools Eyes platform performs validation by taking a snapshot of the UI as the baseline. Applitools Eye tests the framework to compare it with the baseline snapshot using various user workflow or input parameters. The platform, however, does not test for security issues on processes running in the background or those invisible to the user.


SmartBear’s TestComplete uses keyword-driven tests to automate black-box testing. The platform allows testing teams to record scriptless test sequences then play them back in applications using data-driven visual recognition to examine dynamic UI elements. TestComplete supports security analysis on a wide variety of devices, including the support for automated tests across different browsers, applications, and devices.

What is the difference between black box and white box testing?

One of the fundamental differences between the two testing mechanisms is that security and QA teams mainly perform black-box testing. In contrast, developers usually perform white-box penetration testing with access to source code, internal knowledge of implementation logic, design, and the application’s internal structure. Black-box testing techniques describe the application’s behavior and perform functional product tests. On the other hand, white-box testing can be used for logic and algorithm testing to uncover the software’s structural performance and assess internal and external vulnerabilities.

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