White Box Penetration Testing: How It Works

A white box penetration test is a simulated cyberattack in which the penetration tester is given full access to, and knowledge of, the system being tested. With everything from elevated login credentials to network architecture diagrams in hand, the pen tester seeks out and attempts to exploit security vulnerabilities, so that the organization can shore up its defenses following the test.

Because white box penetration testing offers an inside view of the system, the tester can examine points that may get missed during other types of penetration testing, such as issues with the logic flow of an application. White box tests can be very comprehensive, with an especially sharp focus on internal assets.

White Box vs Black Box Penetration Testing

In black box penetration testing, on the other hand, the pen tester is given little to no information about the system. They start with as much knowledge as an actual hacker would, and must break in on their own, just like an actual hacker would. We’ll dig into the pros and cons of each approach below.

Advantages of White Box Penetration Testing

Because white box pen testers start with a full view of the system in question, white box testing is much more comprehensive than black box testing. White box testers can examine every aspect of a system in detail, without having to guess-and-check their way in.

This level of knowledge means white box pentesting is generally more efficient. It isn’t always the faster method, however, since the testers start with more information to sift through. The greater the scope of the pentest, the more time and money it will take.

Because white box penetration testers have an inside view, they can place a greater focus on assessing internal vulnerabilities within a system. They start with access to source code, for instance, which means they can readily discover application logic flow issues that a black box tester might never encounter.

Drawbacks of White Box Penetration Testing

White box penetration testing offers a less realistic simulation of a real-world attack than black box penetration testing does. Just like a real-world hacker, the black box pen tester starts with no information. They have to do their own reconnaissance and find their own way in.

For this reason, black box pentesting is often better for assessing perimeter security. A black box tester is going to spend more time and effort breaking into a system, using techniques such as phishing attacks that a white box tester wouldn’t need to deploy to get into the system. So while white box testing offers a more comprehensive look inside the system, black box testing offers a sharper analysis of what it takes to break in.

White box pentesting can also be time-consuming. It offers a much more comprehensive analysis than black box testing, and it can certainly be more efficient at assessing security vulnerabilities inside a system. But the larger the system – and the scope of the penetration test – the more time and money will be required to complete it. This is especially true when it comes to white box pentesting.

White Box vs Gray Box Penetration Testing

As the name suggests, gray box penetration testing offers a functional middle ground between white box and black box pen testing. Gray box penetration testers typically get limited information about the target system, and may have basic login credentials.

Usually, white box pen testers approach the assessments from a developer standpoint, analyzing systems in-depth to find vulnerabilities. Gray box testers typically mimic an insider threat, working to elevate the lower-level credentials they’re given to access systems they’re not approved to use. In turn, they may reveal different potential exploits than white box penetration testers may find, as white box testers don’t need to alter their credentials as part of the process.

White Box Pen Testing Stages

1. Planning and Preparation

First, white box testers spend time planning and preparing for the assessment. Typically, this involves coordinating with various company leaders and IT employees to get necessary documentation and access. Additionally, there may be meetings to discuss the systems and applications in-depth, ensuring the tester has a complete understanding of the purpose of the assets, the various features, and other details.

Additionally, goals for the test are often outlined during this phase. Essentially, this allows all stakeholders to define the scope of the white box penetration test, ensuring it’s designed to review the assets the company wants to target.

2. Information Gathering

During this stage, the pen tester does some of their own information gathering. Often, they use tools designed to identify vulnerabilities, confirm software and operating systems versions, and collect similar details.

3. Vulnerability Analysis

With all of the information gathered, white box pen testers then start using a range of techniques to find known vulnerabilities – also referred to as common vulnerabilities and exposures (CVEs) – and potential attack vectors. It can also assess various ways to connect to the asset, such as third-party applications that are integrated.

Additionally, pen testers may examine any provided source codes looking for exploitable errors. That gives them further information about vulnerabilities that may further review.

4. Outlining Test Cases

As vulnerabilities are discovered, white box penetration testers typically outline test cases. These define the issues the vulnerability creates, how upcoming tests will unfold, and similar details, creating formal records of what comes next.

5. Executing Tests

After outlining the test cases, the tester will essentially put those plans into action. By doing so, they can confirm if a vulnerability exists, creating opportunities for corrective action.

White Box Pentesting Methods & Techniques

Path Coverage

Path coverage involves examining a path’s flow as it follows various instructions. Along with identifying every possible path, the tester determines if each one is used at least once by the application.

Statement Coverage

With statement coverage, testers essentially review every line of code to find missing lines or unnecessary lines. Usually, unnecessary lines are identified based on whether they’re ever executed.

Branch Coverage

Branch coverage involves assessing execution paths in the code after the application processes a decision statement. The goal is to ensure that no branch results in abnormal behavior by examining each branch thoroughly.

Decision Coverage

Applications are essentially a series of decisions that lead to various results. With decision coverage, every decision is analyzed to ensure that they’re functionally correct.

White Box Penetration Testing Tools

Commonly used white box pentesting tools include the following:

  • CPPUnit
  • EclEmma
  • Efix
  • John the Ripper
  • HTMLUnit
  • JUnit
  • Metasploit
  • Nmap
  • NUnit
  • PyTest
  • Wireshark

About the Author

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Michael X. Heiligenstein

Michael X. Heiligenstein is the founder and editor-in-chief of the Firewall Times. He has six years of experience in online publishing and marketing. Before founding the Firewall Times, he was Vice President of SEO at Fit Small Business, a website devoted to helping small business owners. He graduated from the University of Virginia with a degree in English and History.