Black, White, and Gray Box Testing

In vulnerability testing, ethical hacking, or penetration testing (pen testing), the black, white, and gray colors, though metaphorical, are known to most security professionals in the cybersecurity domain. While none is superior to the others, it’s crucial to choose the right approach for a particular purpose in specific settings.

Black Box

Black box testing is a useful form of penetration testing to help determine vulnerabilities and points of weakness across an organization’s network. Black box testing attempts to simulate a real-world scenario where an attacker might not have full insight into the client’s network. 

The black box testing model operates with limited transparency for a penetration test. The hacker has no knowledge of the organization’s network architecture, and only a few of the security professionals are aware of the test in progress. The black box model of penetration testing attempts to simulate a real-life attack, where hackers would not have knowledge of the organization’s network or security policies.

The black box model of ethical hacking can be split into five main phases: reconnaissance, service determination, enumeration, gaining access, and privilege escalation (Hafele, 2004).

  • Reconnaissance: Initial reconnaissance can provide a wealth of information about the target and can be performed using “readily available public information” (Hafele, 2004). Social engineering is also a method of finding out information about the client.
  • Scanning phase or service determination: Occurs when the ethical hacker is listening to various ports across an organization’s network to determine information such as operating systems and potential vulnerabilities.
  • Enumeration: Penetration testers continue to determine information about network devices such as routers, switches, and servers in the enumeration phase as they scan for vulnerabilities.
  • Gaining access: During this phase, the penetration tester will attempt to compromise systems using cyberattack strategies. Some of these attack strategies involve password cracking, buffer overflow, SQL injection, and denial-of-service attacks.
  • Privilege escalation: Once an ethical hacker has gained access to the organization’s systems, the hacker’s next goal is to attain administrator or root-level permissions. With these permissions, hackers can plant malware that can spread easily across the network. Hackers use rootkits to mask detection and/or a backdoor to maintain entry to the target.

White Box

White box testing, like black box testing, is also one of the primary strategies used by ethical hackers to see ways to defend networks.

The white box model treats the penetration testing team as insiders with knowledge of the organization's network and security policy. Organizations opt for the white box testing model for efficient use of time and money. Using a penetration testing team with insider knowledge of the target network can greatly reduce the amount of time and money to complete this task.

White box testing focuses on the insight and expertise of three primary groups within an organization: upper management, technical support management, and human resources working with legal representatives (Hafele, 2004).

Upper management works closely with the penetration team to provide information about the company's security policy, corporate structure, and process flows. Upper management provides a holistic set of viewpoints that the penetration testing team can use to gain further information about the client. Finally, upper management works with the pen test team to create the much-needed rules of engagement that define the targets and the extent of any breaches that will be made during the test.

Technical support management provides the pen test team with information about technical areas such as physical and logical topologies, firewalls, routers, switches, antivirus software, patch management systems, and other similar information. Another area where technical support management plays a large role is in the security evaluation during and after the penetration test.

Human resources and the company's legal department help ensure the test runs smoothly and ensure there will be no legal issues with breaches made during the penetration test.

White box testing attempts to reduce time and monetary investment by using an ethical hacking team with insight into an organization's security strategy.

Gray Box

If the black box testing treats the network being tested as completely “opaque” with the tester (or the auditor) left with no a prior knowledge of the inner workings of the network or system, and if the white box testing allows complete knowledge (“transparency”) of the internal architecture of the network/system, then the gray box counterpart allows limited knowledge. This implies that the limited information on the internal network is provided to the testing group to help guide the members in their strategy to thoroughly focus on the selected area being tested. The gray approach mitigates the disadvantages that white and black box testing techniques bring.


Hafele, D. M. (2004, February 23). Three different shades of ethical hacking.