Black Box Penetration Testing: How It Works

In a black box penetration test, 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. The black box pen tester identifies vulnerabilities and attempts to exploit them, so that the company can shore up its defenses and 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 pen testers’ lack of access 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 Pen 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 enables the pen tester to adopt 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 trial-and-error tactics, it can be harder to scope than white box testing, and the length of the test can prove unpredictable.

Drawbacks of Black Box Pen 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 Pen 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 external threats, gray box pen testers more closely mirror insider threats. They rely on privilege escalation, in which they attempt to gain a greater level of access within the system. Gray box testing occupies a middle ground: their limited starting viewpoint enables them to probe the system without having to break in first.

For more information, see our full guide to the different types of pen testing.

Black Box Pen Testing Stages

1. Scoping the Test

Before the pen test can begin in earnest, both parties involved must get perfectly clear on the scope of the test. They’ll discuss what systems will be tested, when the test will be take place, and how it will be conducted.

They might also set success criteria: at what point can the testers consider a simulated attack run “successful,” and stop escalating their attacks?

Once both parties have signed a contract outlining how the test will proceed, the pen testers can begin to vet the target systems.

2. Identifying Vulnerabilities.

Now the testers will seek out as many vulnerabilities as they can find. They’ll start with by conducting passive reconnaissance, gathering publicly accessible data from places such as the company website and social media. They’ll also actively scan the target system, using tools such as Nmap and Wireshark to seek out points of weakness.

As they work, the pen testers will compile their findings and draw up an attack plan, which they will continue to build on in the next phase.

3. Exploitation

Now the simulated attacks can begin. The testers will launch their attacks, starting with attempts to break into the system using techniques such as password jacking, social engineering, and more.

Once black box testers break past the perimeter, they’ll renew their search for vulnerabilities as they look to pivot their efforts. From this new vantage point, what new vulnerabilities can they exploit? One common method is privilege escalation, in which a pen tester with basic access attempts to use those privileges to gain higher levels of access, such as admin privileges.

4. The Pen Test Report

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

Vulnerability Scanning

Pen testers use vulnerability scanning tools, such as Nmap and Wireshark, to probe target systems for vulnerabilities. Many of these tools provide preliminary information, which the tester will have to explore in greater detail via manual testing.

Port Scanning

Pen testers will also survey the network to identify open ports, which an attacker might exploit to gain entry to a network. These open ports will often be the locus of exploitation attempts, as the pen testers try to get past any defenses, such as firewalls.

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.

Exploratory Testing

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

Black Box Pen Testing Tools

Common tools used in black box pen tests include the following:

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

About the Author

Find Michael on LinkedIn

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.