Black Box Penetration Testing: How It Works

In black box penetration testing, the pen tester starts with no information or access to the system being tested. They have to gather information and break in on their own, just like a real-world hacker would.

This type of pen test closely simulates an actual attack, and is especially adept at assessing perimeter security. Once a black box pen tester identifies these vulnerabilities, the company can shore up their defenses so as to prevent future attacks.

Black Box vs White Box Penetration Testing

In a white box penetration test, on the other hand, pen testers start with a full view of the system being evaluated. Where black box penetration testing more closely simulates an actual attack, white box pen testers’ high level of starting access allows them to be extremely thorough, especially when it comes to auditing the interior of the system for vulnerabilities.

Advantages of Black Box Penetration Testing

Black box penetration testing more closely resembles an actual attack than white box pen testing does, and is especially adept at identifying vulnerabilities on a system’s perimeter. The lack of information is an asset, in that it makes the black box pen tester a neutral outsider and enables them to adapt a true hacker mindset as they probe the system. Black box pen testers might try approaches, such as phishing attacks, that a white box pen tester would not have to use to gain entry to the system.

Black box pen testing is often faster and less expensive than white box pen testing. But because it relies on guess-and-check tactics, it can be harder to scope than white box testing, and the length of the test might prove unpredictable in comparison.

Drawbacks of Black Box Penetration Testing

Compared to white box penetration testing, black box testing is usually less comprehensive, especially when it comes to internal security. Black box pen testers focus more narrowly on breaking in; white box pen testers thoroughly audit the system from the inside, and can examine things a black box testers would never reach, such as an application’s code.

Black box pen testing is also less efficient, in a sense. White box pen testing can be time intensive, but the pen testers don’t have to worry about breaking in, enabling them to be far more rigorous about examining the insides of the system being tested.

Black 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 usually have low-level login credentials.

While black box pen testers mimic hackers, gray box pen testers more closely mirror insider threats. They often rely on privilege escalation, in which they attempt to gain a greater level of access within the system. Additionally, their limited starting view of the system being tested lets them hone in on areas of vulnerability, without having to break into the system from outside.

Black Box Pen Testing Stages

1. Passive Reconnaissance

Black box penetration testing begins with passive reconnaissance. At this stage, the pen testers gather publicly accessible data, such as IP addresses, websites, company email addresses, and similar details.

2. Vulnerability Scanning

Next, the penetration test progresses from passive to active reconnaissance, as the pen tester scans for vulnerabilities. Now the tester uses tools to scan for open ports and probe the network for faultlines. Software data and user data are also targeted during this phase.

3. Vulnerability Assessment

Now the pen tester analyzes all the data they’ve gathered so far and identifies vulnerabilities they can attempt to exploit. At this point, they hone in on one or more attack vectors and draw up their plan of attack. One common resource used at this stage is the Common Vulnerabilities and Exposures (CVE) database, though a black box pen test isn’t limited to those vulnerabilities.

4. Exploitation

Once a vulnerability is identified, the tester works to exploit it. The exact technique can vary, but it can include malicious requests, social engineering, or any other process that allows them to leverage the vulnerability and gain entry to the system.

5. Privilege Escalation

Once the exploitation step is complete, pen testers aim to escalate their privileges. Essentially, they want to gain access levels associated with higher system roles, such as admin privileges. In doing so, they can access systems that are typically better protected.

6. Reporting

Finally, the pen tester compiles their findings and prepares a report documenting the results of their test. Key sections of the report will detail what attacks were performed, what vulnerabilities were uncovered, and how the company can shore up each vulnerability. This report is the end product of a penetration test; the entire point of the exercise is to identify these vulnerabilities so that they can be mitigated going forward.

Black Box Pen Testing Methods & Techniques

Exploratory Testing

Exploratory testing involves allowing the outcome of each penetration attempt – whether successful or unsuccessful – to guide the next step in the process. Essentially, the tester aims to let the path unfold organically, and they don’t necessarily plan the next step until they accomplish the current one.

Vulnerability Scanning

With vulnerability scanning, pen testers use tools known as vulnerability scanners to check the target IP address for exploitable issues. Often, this strategy provides preliminary information, so the tester explores what it learns with further manual testing.

Port Scanning

Port scanning allows the black pox penetration tester to identify open ports that may expose data or point them toward vulnerabilities. The scans are typically comprehensive, often revealing potential attack vectors.

Data Analysis

During the process, black box penetration testers will aim to gather relevant data and assess the information to see if it’s leverageable. This includes an examination of publicly accessible information, as well as data generated by the target system when specific actions occur.

Password Attacks

Using an automated tool that’s commonly leveraged in brute-force attacks, the tester attempts to force a successful login by relying on a functional list of common passwords. The hope is to find a match, giving the tester access to the system through someone else’s credentials.

Social Engineering

Social engineering involves convincing a legitimate system user to hand over sensitive information – such as login credentials – by imitating a trusted person or entity. Phishing is one of the most common techniques, though others are often employed by pen testers.

Syntax Testing

With syntax testing, pen testers leverage the data input format to find vulnerabilities. In the simplest sense, the goal is to examine outcomes as they use inputs that fall outside of the syntax to see if they prove useful for gaining entry.


Fuzzing relies on noise injection, allowing the pen tester to examine web interfaces and identify missing input checks. If unusual behavior is the result, it could indicate improper software checks, which may be exploitable.

Test Scaffolding

Test scaffolding relies on automation, allowing the tester to use tools to examine system behavior in ways that aren’t always practical with manual approaches. For example, performance monitoring or debugging tools may be used for information-gathering purposes.

Commonly Used Black Box Testing Tools

  • Applitools
  • Appium
  • HP QTP
  • Nikto
  • Nmap
  • Odysseus
  • OWASP WebScarab
  • Paros Proxy
  • Selenium

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.