What are the differences between Blackbox, Graybox and Whitebox testing? Basically, black-box testing is the process of evaluating a system by testing its functionality from outside the system, without knowledge of its internal workings. Whitebox testing is a method that tests internal logic and structures of code. Gray-box testing lies somewhere in between, where some aspects are known and some unknown. All three types share the goal of discovering software vulnerabilities that could lead to malfunctions or data corruption. What really is the difference between Blackbox, Graybox vs Whitebox testing?

Black-box testing

Black-box testing occurs by evaluating the software from outside the system, without knowledge of its internal workings. This is often accomplished by using dummy data or controlled data for testing, depending on the tester’s knowledge of the available inputs and outputs to the program.

This type of testing can be useful in finding bugs that are harder to see in white boxes. An attacker may exploit this vulnerability without having direct knowledge of the exact code.  These types of vulnerabilities are called “black-box” because the attacker does not know what they are looking for maliciously, only that they exist, and where.

Black-box testing is often used for software development because it can help find bugs prior to the distribution of the product. Black box software is generally tested through functional tests (specification tests), where testers merely check that specified features behave as designed and expected on different given input parameters to ensure they perform as needed within an operational environment.
A single unit of black-box testing is a set of test cases developed by a tester who has knowledge about the structure and functionality of the software under test. The test cases can be based on predefined standards for that class of software that have been specified by developers or obtained via other means.
Black box testing is less expensive and more straightforward than white-box tests. It is also far less time-consuming because testers can check several features or even the entire program in one run rather than having to test them one at a time as in white box testing.

This method is not without its shortcomings, however, and calls to a “white-box” approach are increasing. White box testing approaches focus on the internal workings of a system.

White-box testing

White-box testing takes a look at a program from both inside and outside. It tests internal logic and structures of code during its test process. This might not be related to the outer or visible working of a program, and it can be different from the expected outcome on both. This type of testing is often done to identify security flaws in software. White box testing attacks may expose vulnerabilities that are not exploitable in black-box tests, but they also cannot find those that are.

White boxes reveal vulnerabilities that are not normally visible in black boxes; they can also find problems with hardware or software that aren’t readily apparent in black-box tests. These tests are designed to be thorough by providing the tester with a complete view of the software in question and can be used for both prepublication and finished code testing.

White box testing is, therefore more costly than black-box, as it requires additional programming knowledge (and often large amounts of it), but also yields better results. It is also very time-consuming, as algorithms that cannot be found by black-box methods may need to be developed to detect vulnerabilities in white-box tests.

There are two major types of white-box testing: Signature-based and fuzzing-based.  Signature-based is done by comparing the behavior of the program to a predefined set of known attack signatures. Each piece of software will have a list of signatures; these signatures will define the known capabilities and security vulnerabilities for that software.
Fuzzing-based is done by using testing tools to test hundreds or thousands of inputs and searching for errors in the program. The output of this testing can be used to identify other vulnerable inputs, which can then be tested simultaneously.

White-box testing offers more security benefits but is still not completely secure because it does not offer testers complete control over the product under test. It also lacks accuracy when looking at “attack signatures” (i.e., finding a way to exploit a system by knowing what a vulnerability looks like).

White box testing has its drawbacks as well, however. For instance, it can take a long time to find certain vulnerabilities that may already be known to the software developer. Further, if new releases of the software are available that have not yet been tested against the previous release, there is no way of knowing whether or not old vulnerabilities still exist.

Gray-box testing

A test environment in which some aspects are known and some others unknown is called a gray-box test. This involves having knowledge of the internal workings of the software but with an unclear idea of what the software does.

The tester is given partial information about the program, but not enough to fully understand it. The tester may or may not know how to exploit vulnerabilities that could lead to malfunctions or data corruption. Testing using these methods can identify problems with either black-box or white box testing approaches on their own.

Gray-box can be seen as a compromise between black box and white box testing, where some aspects are known and some are unknown.

Conclusion

Various levels of quality assurance are used throughout the software development process. They range from ensuring that a program can be operated to looking for bugs or defects in the functionality. All the stages of testing have their own purpose and are performed to find different kinds of errors in a software product. During testing, it is important that all types of problems are found and fixed. There should be a balance between black box and white box testing because while black box methods tend to not show every issue that can arise in a system, white box testing might be too expensive or time consuming to do on every single piece of code written on a project.

Read more about things to consider when choosing a software tool.