Black-box penetration testing: Cyber security testing methodology

Black-box penetration testing: Cyber security testing methodology

Last updated: May 8, 2024

  1. What are black-box penetration testing tools
  2. What is the black box penetration testing methodology?
  3. Black box penetration testing example

In the days of modern age technology, with continuous technological developments and improvements, individuals and organizations need to become more aware of the risks that they are facing. It is imperative to educate oneself and those around us in order to avoid becoming vulnerable and falling victim to various malicious and evil cyber-attacks. There are many ways of conducting penetration tests: white-box penetration tests, grey-box penetration tests, and black-box penetration tests. In this essay, we will focus on black-box penetration testing in particular. We will cover the necessary topics regarding black-box to understand what this is all about and its importance. We will focus on testing tools, methodologies, procedures, advantages, and a few disadvantages.

What is penetration testing? And why is it important to us as individuals/small or big organizations:

  • Penetration testing (PT), which is also called a “pen-test,” is a type of test that causes an intentional launch of a cyber-attack. This might be conducted by smaller or larger organizations on their devices and systems, ensuring that they are protected and prepared for any weaknesses or potential vulnerabilities that unauthorized users might exploit. This test provides little – to – no break-ins from these external individuals who wish to hack into their systems.
  • This test is conducted for the sole reason of revealing any weakness in a system.
  • A firewall is a type of security system that controls network traffic, no matter whether it is incoming or outgoing.
  • Penetration testing enhances this firewall, in turn improving it.
  • This penetration test (PT) will be able to expose vulnerabilities, assisting organizations in generating countermeasures to reduce the risks of a break-in, ensuring that their systems run smoothly, functioning properly and effectively.
  • Although the penetration test is mainly conducted in order to uncover any security weaknesses or vulnerabilities, pen-testing might also be used to examine the robustness (reliability or validity) of a business’s security policy
  • Penetration testing can either be conducted in an automated manner, or it can be manually conducted by a security expert.

What is a black box?

It is essential that a company properly understands which type of testing method might be most useful to them, considering their systems, software, and networks. Furthermore, it is imperative that an organization understands that the cheapest penetration test or the quickest penetration test might not actually be the most suitable choice for them. We will briefly highlight the three different types of penetration tests (black-box, white-box, and grey-box); however, we will remain with a deep focus and concentration on black-box penetration testing.

What is black box penetration testing?

black box penetration testing - zero knowledge
Black box penetration testing security assessment method

Black box penetration testing is a security assessment method that provides testers with limited information about the target system. It is an important part of any comprehensive security review and helps identify vulnerabilities in applications and networks by simulating real-world attacks. During this type of testing, testers are provided with no prior knowledge or access to the system’s source code or configuration. Instead, testers use their expertise to analyze the target system’s behavior and attempt to exploit any discovered vulnerabilities.

  • Black box penetration testing is conducted by an individual who is considered an average hacker.
  • This individual has no real knowledge about the device or the systems on which they will conduct an attack. Their knowledge remains external as they are an outsider to the system.
  • These “ethical hackers,” in fact, do not even know anything about the architecture of the device, nor do they see the source code.
  • This test is conducted in order to reveal weaknesses and vulnerabilities that can be exploited by external users outside the network.
  • In order to conduct a black-box penetration test, the tester needs to be able to use dynamic analysis within the said target device.
  • This tester must have some knowledge of scanning tools in order to conduct this penetration test manually.
  • These testers also need to generate their own map of where they will target and do so strategically, as no architecture will be shown to them.
  • This tester, in fact, has little to no knowledge, which can allow for a quick and efficient running of a penetration test.
  • A real concern present is the chance of the tester not breaching the perimeter, meaning many weaknesses in these devices and within these system networks might stay unnoticeable to the organization or the individual.

What is white-box penetration testing?

White box penetration testing - tester knows the system's
White box penetration testing – tester knows the system’s

White box penetration testing is a form of security assessment in which the tester knows the system’s internal details, such as source code, network infrastructure, and architecture. This type of testing is considered more thorough than black box penetration testing, as the tester can explore every corner of the system and analyze it from a more holistic perspective. The tester can also look for vulnerabilities and misconfigurations that would be difficult to detect with black-box testing.

  • White-box penetration testing, which is also commonly known as crystal or oblique pen-testing, follows the meaning behind its name. It allows the tester to gain full access to the network/software/system and device on which they are working in order to complete the penetration test.
  • During this type of penetration test, the tester is given complete instructions surrounding the internal makeup of the system or the device. This all ensures that all the parts of the systems and the devices are being exercised and tested.
  • This penetration test is extremely thorough as the tester knows all they need to, for example, understanding the system’s code or the application’s design.
  • By giving full access to the tester, the organization or individual is able to save the time taken and reduce the amount of money used whilst conducting this penetration test.

What is grey-box penetration testing?

Gray box penetration testing which combines black and white box methods
Gray box penetration testing which combines black and white box methods

Gray box penetration testing is a type of cyber security penetration testing, which combines black and white box methods to assess the vulnerability of a system, network, or application. During this type of test, testers have some knowledge of the system under examination, such as the architecture, software components, and potential attack vectors. Gray box penetration testing helps identify potential security flaws and vulnerabilities in a system that may be exploited by an attacker.

  • This type of penetration testing is somewhat in the middle of the other two tests (black box and white box).
  • During this penetration test, the tester is given some internal information about the system, software, or device but not everything, keeping the information released somewhat limited to them in order to conduct the penetration test.
    • An example of this might be: the tester might be given lower-level credentials about the system, and by doing this, this might allow for a more accurate and efficient approach to testing.
  • This type of penetration testing allows for an efficient test (similar to a white-box pen test), meaning it’s quick and good, but also an authentic test (similar to a black-box pen test), meaning it’s showing true and real results.
  • Additionally, the pen-tester does not have to be in need of access to the source of the code, and it is a non-intrusive method and completely unbiased.

Black-box methods/the stages of conducting a black-box penetration test:

There are five main stages when it comes to conducting a black-box penetration test, namely: reconnaissance, scanning & enumeration, vulnerability discovery, exploitation, and privilege escalation. We will delve into each one of these in great detail.

Stage 1: Reconnaissance

This first stage of black-box penetration testing involves accumulating preliminary information about the device or the system on which the tester is ethically hacking. The types of information that they will collect include IP addresses, various employee information, email addresses, and any pain points.

Stage 2: Scanning & Enumeration

Additional reconnaissance is conducted in this second step. The tester will collect additional information from the targeted device or network during this stage, including the type of software, the operating system, connected systems, and user accounts or roles.

Stage 3: Vulnerability Discovery

During this third stage, the individual conducting the test will gather information about the vulnerabilities of the systems or networks that are publicly available. For example, this includes CVEs in the system or third-party applications that are utilized by the targeted network/device.

Stage 4: Exploitation

During this stage of the black-box penetration test, the tester will build malicious actions in order to exploit any potential weaknesses. During this stage, the tester gains access to the main part of the system, doing so in the shortest time period possible.

Stage 5: Privilege Escalation:

This stage occurs following the tester gaining access to a system, and they then go on to attempt to gain complete access to the system or device.

Black-box penetration test techniques:

  • Decision Table Testing (DTT)

This black box penetrating technique allows for the testing of multiple combinations of inputs simultaneously. In this technique, there is a table that shows the inputs and what their various outcomes are. This is considered a tabular representation. For example, a health insurance company can supply a premium based on the age of the person who has the insurance (under 60 or over 60) and whether or not they smoke. This allows for the making of a table with four different rules, allowing for four different outcomes.

  • Equivalence Class Partitioning (ECP)

This technique of black-box penetration testing separates inputs into various different categories of data. Dividing the classes allows for the opportunity for the generation of new test cases. Each of these cases is able to figure out correct or wrong states.

  • Error Guessing (EG)

This penetration testing technique consists of trying to guess the most important errors in the code. This guessing technique assists in figuring out many defects that the usual systemic approaches might not be able to locate. This relies on the tester’s previous experience with the system they are working on and their ability to discover the areas where errors might actually occur. Usually, functions require very specific types of arguments to generate the needed output. An example of this is a function that requires a string as its only argument. Suppose the function is given a string as an argument, and the function has a correct algorithm. In that case, it should work properly and give the user the correct input. However, if the function is given a numeric value despite it needing a string, then the function can behave in different ways. If the function has a fallback that returns a default value if something goes wrong, then that function is well protected against edge cases. In the case that the function doesn’t cover this case, then it could return a value we didn’t expect or even crash the entire application because of an unexpected type.

Various testing types are conducted via the black-box method:


  • This type of test is used to analyze each of the functions within the respective software. A test requires input and provides an output. If the feedback given generates the correct production described by the test for a function, then that instance of the test has passed.


  • This type of test demonstrates that an application that is working is still acting and performing correctly after certain revisions. These tests ensure that everything has remained the same.

Non-functional testing

  • This type of black-box testing confirmation of a particular instruction/specification sets the bar for the performance of a specific system. Some of these requirements involve usability, efficiency, and security.

Six main tools of black-box penetration testing:

  1. Syntax testing
  • This tool of black-box penetration testing is conducted to examine the data input format present within a device or a system.
  • This is often conducted by adding inputs that contain wrong or misplaced elements in order to figure out what might occur by putting these elements into the system. This is done to test what will happen if inputs begin to deviate and move away from the original syntax.
  1. Fuzzing
  • This type of black-box penetration testing tool examines the interfaces of the web to discover any input that might actually be misplaced or missing. This is conducted via a noise injection, which is well-crafted data that examines the system in order to detect or find any weird program behavior.
  • This will then correct the data that is being used with the help of utilizing “fuzzers.”
  1. Data analysis
  • This tool of black-box penetration testing is the type that reviews the data in the targeted system. It assists the tester in discovering the targeted system or device’s internal functions.
  1. Exploratory testing
  • This is a type of black-box penetration testing that is conducted without organizing or generating a plan. Additionally, within this type, there are no ideal or specific outcomes. This allows for any outcomes of the first test to provide guidance to the next one as there is no plan to follow through.
  1. Test scaffolding
  • Test scaffolding is a type of testing that aims to automate the process of testing parts of a program. This can happen in the shape of unit testing, integration testing, query testing, and other sorts.
  1. Monitoring program behavior
  • Monitoring a program’s behavior can be done in a variety of ways. A few examples are manual QA testing, automated testing like web scraping, or testing using integrated program analytics to collect data on behavioral clicks that our user provides.

Black box penetration testing example

Black box penetration testing is a method where the tester simulates an external cyber attack without any prior knowledge of the internal workings of the system being tested. Here’s an example scenario of black box penetration testing:

Example: Online Banking Application Black Box Penetration Test


To identify security vulnerabilities in an online banking application from an external attacker’s perspective.


  1. Reconnaissance:
    • The tester starts by gathering information about the target application. This involves identifying the public-facing URLs, server information, and technologies used in the application. Tools like Nmap and Nessus might be used for scanning open ports and services.
  2. Testing for Vulnerabilities:
    • Input Validation Testing: The tester attempts SQL injection, cross-site scripting (XSS), and other input attacks to see if the application is vulnerable to malformed or malicious input.
    • Authentication Testing: The tester tries to bypass login screens or session management flaws. This could involve brute force attacks on login forms to test password strength policies.
    • Testing Business Logic: The tester looks for flaws in the application logic, like the ability to transfer funds without proper authorization or limits.
  3. Exploitation:
    • Upon finding a vulnerability, the tester attempts to exploit it. For example, using an SQL injection flaw to access sensitive customer data or modify transaction details.
  4. Reporting:
    • The tester compiles a detailed report, including the vulnerabilities found, the methods used to exploit them, and the potential impact. Recommendations for fixing the vulnerabilities and improving the overall security posture of the application are provided.
  5. Re-Testing:
    • After the vulnerabilities have been addressed, the tester re-tests to ensure that the fixes are effective and that no new vulnerabilities have been introduced.

Black-box testing procedure:

  1. First and foremost, one needs to examine the software’s instructions/specifications
  2. Next, the tester must choose the right units to authenticate. After this, choose inappropriate inputs to verify
  3. Now the tester must find the right output for all the inputs
  4. One must now write test cases by utilizing the selected inputs
  5. Execute the various test cases
  6. One must now ensure that the realized outputs against the intended outputs
  7. Now the tester must debug the system and then retest it

Why should I conduct a black-box penetration test? How does it benefit me?

  1. This type of testing allows for the tester to location errors in functional specifications.
  2. This type of test allows for a ‘real-life’ situation, conducting the test as if it’s being done by the user in order to receive unexpected results.
  3. The tests are completely unbiased, as the tester is independent of the system.
  4. Allows for the detection of very common weaknesses, for example, SQL injection, XSS or CSRF
  5. It discovers any incorrect product builds, for example, missing files.
  6. It allows for the discovery of security issues that are related to people by employing social engineering tools.

Possible disadvantages of conducting black-box penetration testing:

In black-box penetration testing, no internal testing is conducted. Thus a device or system might appear to be secure if the person conducting the test is unable to find or discover any weaknesses from the outside, which can be extremely detrimental to the organization.

Some weaknesses:

  1. Black-box penetration testing does not allow testers to preview a full image for the targeted system.
  2. Black box testing is purely based on trial and error, and there is no deep analysis conducted; thus, the testers are guessing.
  3. If the tester is not necessarily an expert, an ‘easy’ vulnerability might take a long time to detect the weakness or vulnerability.

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