Difference between Internal and External Penetration Testing

Penetration testing is a cybersecurity procedure during which a team of specialists checks networks, software, hardware, applications, etc., for security weaknesses. Essentially, penetration testing is ethical hacking performed for the benefit of the company that orders the test on its own systems.

In some fields such as financial services, healthcare, and government system access, penetration testing is required by regulators, while it is voluntary in others. Penetration testing is an important information security technique that should be included in an organization's governance framework in the face of constantly shifting threats.

Network penetration testing, also known as 'infrastructure penetration testing', can be conducted from two angles: inside and outside your organization's network perimeter.

Here are a few examples of frequent network pen testing scenarios −

  • Monitoring modifications to a company's network infrastructure to make sure no vulnerabilities are introduced.

  • Following a business merger or when a company is acquired.

  • To satisfy the demands of a third-party such as an insurer or a business associate.

What is Penetration Testing?

With assaults becoming more sophisticated and pervasive, it's more critical for businesses to do regular penetration testing to detect vulnerabilities, plug holes, and ensure that cyber controls are functioning properly. These tests enable the company to adopt a proactive approach by detecting weaknesses in its infrastructure (hardware), applications (software), and personnel in order to establish continuous and adequate controls that can keep up with the ever-changing cyber threat landscape.

Pen testing or ethical hacking are other terms for penetration testing. It refers to the deliberate launch of simulated cyberattacks to find exploitable flaws in computer systems, networks, websites, and applications. Pen testing tools can be used to assess the robustness of an organization's security policy, regulatory compliance, employee security knowledge, and the organization's capacity to identify and respond to security issues as they occur and identify security vulnerabilities.

Steps in Pen Testing

There are five steps to the pen testing technique.

Reconnaissance and Planning

  • They define a test's scope and objectives, as well as the systems to be tested and the testing methodologies to be employed.

  • Obtaining intelligence in order to have a better understanding of a target's operations and potential vulnerabilities.


The following step is to determine how the target application will respond to various forms of intrusion attempts.

Obtaining Entry

To uncover a target's flaws, this stage utilizes web application attacks like as cross-site scripting, SQL injection, and backdoors. Testers then attempt to exploit these flaws, usually by increasing privileges, stealing data, intercepting communications, and so on, in order to determine the extent of the damage they can inflict.

Keeping Access Open

This stage will assess whether the vulnerability may be exploited to establish a long-term presence in the compromised system, allowing a bad actor to get access to sensitive information. The idea is to imitate sophisticated persistent attacks, which may remain in a system for months and steal a company's most sensitive data.


Data that was obtained was sensitive. The time the pen tester was able to remain undetected in the system.

Penetration Testing – Why Is It Important?

The major reason penetration testing is essential for an organization's security is that they teach employees how to deal with any form of a malicious break-in. Pen tests are used to determine whether or not a company's security practices are genuinely effective.

Pen testing may also identify which of your company's or application's channels are the most vulnerable, indicating which security technologies or protocols you should invest in. This approach may uncover a lot of serious system faults you were previously unaware of.

Reports from penetration testing can also help developers make fewer mistakes. When developers understand how a malicious entity launched an attack on an app, operating system, or another piece of software they helped create, they'll be more committed to learning more about security and less likely to make similar mistakes.

Pros and Cons of Penetration Testing

This has a number of advantages, including the ability to detect a wide range of weaknesses. They can spot high-risk flaws that are the outcome of a collection of minor imperfections. Reports will contain explicit recommendations.

There are a few significant issues. Failure to conduct tests correctly can cause servers to fail, reveal sensitive data, corrupt critical production data, and various other problems connected with simulating a criminal breach. You must have faith in the penetration tester. The results will be deceiving if you don't use realistic test settings.

WAFs and penetration testing are two different but complimentary security strategies. Some compliance criteria for security auditing methods, such as PCI DSS and SOC 2, are met by pentesting. Specific standards, such PCI-DSS 6.6, can only be satisfied with the usage of a certified WAF. However, owing to the aforementioned benefits and the ability to adjust WAF settings, pen testing is still beneficial.

What is Internal Penetration Testing?

An internal network pen test is used to determine what an attacker could do with initial network access. Insider threats, such as personnel acting maliciously, whether purposefully or accidentally, can be mirrored by an internal network pen test. When conducting an internal penetration test, a cybersecurity team will examine wireless networks, servers, computer systems, and other devices, firewalls, IDS/IPS, and even staff behavior and procedures.

Once the vulnerabilities in those components have been found, cybersecurity experts will attempt to exploit them in order to determine the scope of potential unauthorized access and damage. This type of test is better suitable for enterprises with a big number of employees, corporations that retain sensitive data internally, or companies wanting to meet regulatory standards like PCI-DSS.

While it is an important part of risk management for enterprises, it should not take precedence over external penetration testing when security testing resources are scarce.

What is External Penetration Testing?

An external network pen test is used to evaluate the efficiency of perimeter security policies in preventing and detecting attacks and find flaws in internet-facing assets like web, mail, and FTP servers. Cybersecurity professionals regularly undertake identity management, cryptography weakness assessment, authorization, and authentication testing, error handling evaluation, and many other external penetration tests.

IDS/IPS testing, foot-printing, manual testing, password strength evaluation, system, port, and service scanning, and other methods are commonly used in these tests. Organizations can cover their most notable risks that are most likely to be exploited and result in an incident with the help of an external pen test.

Organizations with a low cybersecurity budget can rely on external pen testing to protect their systems and assets against the most common type of cyberattacks they experience on a regular basis.

Differences between External and Internal Penetration Testing

The following table highlights the major differences between Internal and External Penetration Testing −

Internal Pen TestingExternal Pen Testing
Internal penetration testing replicates an internal threat and reveals what may be accessed without authorization within. In this case, the attacker already has some authorized access and is well-known within the company.It is a type of remote penetration testing that simulates the most prevalent method of hacking a company's systems.
Its primary purpose is to figure out what a malevolent or unhappy employee could do or what the consequences of malware spreading throughout the company's networks would be.External pen testing's major purpose is to detect and resolve an organization's most serious cyber threats constantly being examined by automated tools and hackers.


Penetration testing is a critical technique that businesses must employ to understand how vulnerable their systems are to attackers. Internal penetration testing should not be overlooked, but it is not a top concern because internal threats are few. On the other hand, external threats are constantly changing, common, and the most difficult to cope with.