Are you also finding it difficult to choose the right testing method for your project? You are not alone. Many of our clients face the same challenge when deciding between the three common types of tests. In this article, you will find a comparison that will help you choose and explain the most important differences.
What is the same for all types of tests: It is about finding errors in a system. The main difference is how much information the tester receives.
But what is our goal in determining which test to perform? Presumably, one would first mention efficiency: as many errors as possible for as little budget as possible! But this is only partially correct. Errors should also be relevant, which is why a measure of relevance must be taken into account in the number of errors. What may not sound so difficult at this point turns out to be less trivial in real life. The same error can be differently relevant in two different places.
A typical example: An application to be tested has 15 errors, 5 serious and 10 minor. Two of the serious ones are exploitable from the internet, three cannot be exploited from the internet, but help an attacker who has already made it onto the system. Ten other simple errors are distributed throughout the application. If we manage to find seven errors with a pentest, the two serious ones from the internet should be among them if possible.
Blackbox Pentest – „No Information“: The view from the outside
In this form of testing, the tester behaves exactly like an external attacker. Nothing is known about the application except for a public URL or IP address. The framework conditions of the test are agreed with the security officer, and the application's project team has no contact with the test team.
Advantages
Blackbox penetration tests are extremely easy to set up and carry out. Apart from a brief agreement on which systems are in scope, no further coordination is necessary. The tester concentrates on the errors that can be found from the outside. No communication with the project team is necessary. It is also possible to test systems where no cooperation with the project team is possible – for example, purchased appliances. This makes the black box test very realistic.
Disadvantages
The realism comes at the cost of the tester having to work out all the information about the system themselves. This includes not only the technical functionality and the search for vulnerabilities, but also the operation of the application itself, different user and authorization groups, etc. If you look at the efficiency of such a test, it is certainly the lowest.
Whitebox Pentest – „Information push“: Full insight, full control
This test form describes the exact opposite of a black box test. It is an attempt to increase the efficiency of the test by providing any information. This may mean that the tester receives source code, architecture diagrams, documentation, access to operating systems, etc. The tester may be able to set up a system themselves and keep an eye on error logs during the test.
The tester/auditor is initially overwhelmed with all the information, the so-called "information push". Often this analysis is no longer called "test" but "audit", e.g. source code audit, host audit, etc.
Advantages
The advantage of a very elaborate kick-off is that this type of error detection is the most thorough. In principle, errors can be found in all systems, even those deeper down.
Disadvantages
Let's start with the disadvantages this time: Anyone who has ever trained a new team member in a team knows the effort it takes until the new colleague has read up on everything. In principle, this is a similarly complex onboarding process. It is not uncommon for non-disclosure agreements to have to be signed, source code has to be cleaned up for certain things, access to documentation is required, etc.
Gray Box Penetration Test – "Information pull": An Efficient Middle Ground
Here, a compromise is sought. Representatives from the project team are also present at the kick-off meeting. The application and its functionality are discussed and do not have to be "worked out" by the tester. The tester has the opportunity to ask functional and technical questions. Typical questions here are:
- How is the data stored? SQL/NoSQL?
- Which database is used?
- What different user roles are there?
Afterward, the tester has the opportunity to gain access to areas that he considers useful. Typical here are accesses to the application to test technical functions.
As with the whitebox pentest, the tester is in contact with the project team and can ask questions about functions during the test: "The behavior is strange at position XY, can you send me the source code for this position?" The tester does not receive all the information in advance, but obtains each piece of information individually (→ information pull).
Advantages
The onboarding and test setup is only slightly more complex than with the Black Box test. The tester also concentrates first on the vulnerabilities that are accessible from the outside.
Disadvantages
The Gray Box Penetration Test requires good cooperation between the tester and the project team. The team must be willing to find errors. What sounds banal here is unfortunately not always common practice. Often, a security officer wants to "prove" that an application is insecure. Sometimes it also happens that a system is to be tested before it is purchased.
Conclusion
The choice of the right penetration testing method depends largely on the objective, budget and timeframe.
Anyone with a very limited budget or time window, such as one or two days, is well advised to use a blackbox test. This is especially true for purchased systems that are not trusted but for which no documentation is available. The test requires little preparation and realistically simulates what an external attacker sees. However, the yield is usually limited, especially with more complex systems.
A White Box test is worthwhile if the tester is intensively involved. For example, if I want to have a tester as a consultant in my project for weeks or months, the high initial effort will be rewarded with thoroughness. The effort can also be justified for high-value systems.
Graybox tests offer a good middle ground: the tester receives specific information when it is needed without being completely integrated into the project. The kick-off is manageable, but collaboration with the project team is necessary. This makes graybox particularly efficient, with a good balance between effort, realism and test result.
Are you still unsure which penetration testing method is best for your company or do you have specific questions? Let us clarify your individual requirements together.
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