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Black-Box Penetration Testing: Pros and Cons

December 3, 2021
Oliver Moradov

What is Black-Box Penetration Testing?

The term black-box penetration testing (pentesting) refers to external tests aimed at identifying vulnerabilities in systems, applications, or networks. Unlike other forms of security testing, penetration testing can verify that vulnerabilities are exploitable by attackers, and show exactly how. Black-box penetration testing is also known as external penetration testing or trial and error testing. 

A black-box pentest is performed by an external party, or an automated system, which is completely unfamiliar with the target. During the test, the pentester attempts to imitate the behavior of an unprivileged hacker to simulate a real attack. It means the pentester is responsible for the reconnaissance phase of the attack, during which they gather any sensitive information needed to penetrate the network.

After gaining the necessary information, the black-box pentester draws up a map of the targeted system. The map is created according to the pentester’s observations, research, and analysis—similarly to how an unprivileged attacker would map the target. 

Next, the pentester uses these findings to attack the target. They may use any necessary means, including password cracking and brute force attack. After the breach, the pentester attempts privilege escalation and tries to establish a persistent presence, like an attacker would, but of course without causing damage. At the end of the test, the pentester prepares a report and cleans up the environment. Read our guide to penetration testing reports (coming soon)

In this article:

Pros and Cons of Black-Box Penetration Testing

Pros of Black-Box Penetration Testing

A black-box pentest provides the following advantages:

  • Simulates a real attack to discover unexpected results.
  • Identifies exposed vulnerabilities.
  • Identifies implementation and configuration issues by testing the application on run time.
  • Detects incorrect product builds, such as missing or old or modules and files.
  • Employs social engineering techniques to discover security issues related to people.
  • Locates security issues that occur due to interactions with underlying environments, including improper configuration files and unhardened operating systems.
  • Find error issues, such as information disclosure in error messages and input or output validation errors.
  • Looks for common vulnerabilities, such as SQL injection, XSS, and CSRF
  • Checks server misconfiguration issues. 
  • Helps fix flaws quickly by providing detailed remediation information.

Cons of Black-Box Penetration Testing

A black-box penetration test does not offer a comprehensive review of your source code and internal systems. A black-box pentest that discovers issues indicates that the target has a weak security build. However, a black-box pentest that cannot guarantee the target is secure. The target may still have internal issues hidden beneath the surface.

A black-box pentest is based on the guesswork, trial, and error of the external party contracted to perform the test. The pentest can be quick and end after the identification of vulnerabilities, or it may take months of reconnaissance until the pentester identifies one vulnerability. The time range depends on the expertise of the pentester and other criteria.

Related content: Get a better understanding of how penetration testing services work

Black-Box vs. White-Box vs. Grey-Box Penetration Testing

What is White-Box Penetration Testing?

White-box pentesting refers to tests that involve sharing full system and network information, including network maps and credentials, with the pentester. The information helps reduce the total cost of an engagement and save time. A white-box test can help you try multiple attack vectors to see which can breach a specific system.

What is Grey-Box Penetration Testing?

The term grey-box penetration testing refers to tests during which organizations share limited information with the pentester, usually login credentials. A grey-box test can simulate an insider threat as well as an attack by an external threat that breached the network. A grey-box penetration test can help you determine which type of access level a privileged user can attain and what damage this escalation can potentially cause. 

Related content: Read our guide to network penetration testing.

Engagement Accuracy

The main objective of a pentest is to find and patch any vulnerabilities that an external attacker can potentially exploit. A black-box pentest can provide the most accurate engagement for this purpose because the pentester is not given any insider information. 

Threat actors usually have more time to devote to an attack than a pentester. Grey-box and white-box pentesting help pentesters reduce engagement time by increasing the level of information provided before an attack is simulated. 

The main concern is that the information provided during white-box and grey-box tests may cause testers to act differently than a black-box hacker would. This information can potentially lead the pentester to miss vulnerabilities that a less-informed attacker might exploit.

Learn more in our detailed guide to web application testing.

Speed, Efficiency and Coverage

Each pentesting methodology makes tradeoffs between efficiency, coverage, and speed. Here are key differences:

  • Black-box penetration testing—is considered the fastest pentest type. However, because pentesters have no insider information on the targeted system, they may miss vulnerabilities. The lack of information can decrease the efficiency of the pentest.
  • Gray-box testing—may take longer to perform compared to black-box tests. However, a grey-box test provides a higher level of efficiency and coverage because pentesters get access to certain information before launching an attack. For example, access to design documentation helps testers to focus their efforts.
  • White-box testing—is considered the slowest but most comprehensive type of pentesting. White-box pentesters get large amounts of data, which take time to process. However, the scope of information and high level of access can significantly improve the probability of identifying and remediating both outward-facing and internal vulnerabilities.

Complementing Penetration Testing with DAST

Penetration testing, whether carried out by a 3rd party testing firm or internally by a security team, will leverage Dynamic Application Security Testing (DAST) scanners for their preliminary scans. These tests are carried out periodically, whether monthly, quarterly or in most cases, annually. 

With rapid release cycles and CICD however, security tests need to be run more frequently to be secure, ideally on every build to detect and fix security bugs early and often, to remove manual bottlenecks.

Bright’s DAST scanner automatically detects security vulnerabilities in your web applications and APIs, validating every finding before reporting it to you and your team, with NO false positives.

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