The Difference Between Internal and External Penetration Testing & When To Consider Both Options

Although routine scans and assessments are necessary to identify surface-level vulnerabilities, it’s crucial to get a holistic view of your organization’s security posture through in-depth testing. 

Penetration testing is the process of simulating an attack on your organization’s systems. Depending on the type of pentest, this review allows penetration testing experts — also known as pentesters — to test your organization’s defenses by assuming the role of an external attacker or someone who already has entry-level internal access to your systems and network. 

Both internal and external penetration tests can provide better protection for your network at all levels. But when do you need which test, and what are the differences? Here, we’ll discuss internal vs external penetration testing and when you might need them.


What Is the Difference Between an Internal and External Network Pentest?

Ideal pentests use a specific framework and predetermined objectives so the pentesters can find potential weaknesses. Different penetration testing types will have different goals, starting points, and end points.

External Penetration Testing

In an external network penetration test, the pentesters remotely search for security vulnerabilities in internet-facing assets such as web, mail, and different servers. They attempt to breach your defenses to access the internal network of your organization. 

External penetration testing involves:

  • A pentest framework and set objectives to achieve.
  • Identification of vulnerabilities on public-facing assets such as websites and external applications.
  • Simulated attacks at various external weak points.
  • Password strength testing, footprinting, testing firewalls, and more.
  • Reporting the findings so your organization can tackle remediation steps.


An external network pentest can be equated to someone going around your house to find all the ways they could break in. Small cracks in a window or near a doorway could open up with the right amount of pressure. 

The same can be said about an application with connections to servers, firewalls, and switches. Multiple vulnerabilities could be found, such as open ports, outdated virus applications, and zero-day exploits. 

External network penetration tests can be time intensive and complicated, especially if done right. It can take specialists 2 to 3 weeks to complete an external pentest, and the testing is only complete once a simulated data breach occurs. After this point, an internal penetration test would provide insight on how far a threat actor could go into your systems.

Internal Penetration Testing

Internal network penetration testing — also known as an internal network assessment — identifies vulnerabilities in the company's systems by attempting to compromise its software and computer systems from the inside. 

This type of pentest begins with the same basic permissions that an employee would have or with what a threat actor would have if they’d already breached your external defenses. 

Internal network penetration testing involves:

  • A pentest framework and set objectives to achieve.
  • Identification of vulnerabilities on internal-facing assets such as websites and applications.
  • A simulated attack at these vulnerable points.
  • Utilizing internal network scanning, exploiting, and firewall testing.
  • Reporting the findings so your organization can tackle remediation steps.


In most cases, the goal of the pentest is to determine how easy it would be for an intruder to gain access to confidential information. These engagements can take anywhere between 3 to 6 weeks and are a greater monetary investment, but they provide a full scope of how threat actors can move laterally through your system if they were to gain internal access to your network.

Internal pentests can also be combined with other tests, such as social engineering and phishing attacks, to give you a bigger picture of your security status.


Which Penetration Test Type Is Best for Your Organization?

Depending on your needs, your organization could benefit from one or both test types.

External Pentesting Can Help If:

  • You’ve already had an external data breach and are looking to improve your  security.
  • You’ve recently launched new public-facing websites, applications, FTP servers, and more.
  • You’ve done routine testing such as vulnerability scans, but have never had a true test of your perimeter security.

Internal Pentesting Can Help If:

  • You’ve had an external penetration test and want to see how far a threat actor could get inside your system.
  • You suspect your infrastructure may be insecure.
  • You’ve been the victim of an internal attack before.
  • Your employees have not been trained in cyber security awareness and may leave vulnerable user escalation points.
  • Your internal systems have multiple internal software platforms and update patches that could be vulnerable to attack.


Internal and External Penetration Testing

If you want a full view of how a threat actor could breach your external security and what they can do once inside your network, an internal network pentest can be layered with external network testing. 

With back-to-back testing, you’ll get a full picture of your cyber security posture and have limited interruptions of your daily operations. It may also be easier to simultaneously evaluate the reports from these tests and prioritize the most important remediation steps. 


Protect Your Network From Internal and External Threats

If you know the security level of your organization — and its vulnerabilities — you can prevent devastating attacks on your business. Since the difference between internal and external penetration testing is centered around “where” it happens, it’s crucial to find out which areas of your organization need a deeper look.

Are you ready to see where you stand against threat actors? Take our self-assessment today to understand your organization’s current cyber security posture.


Topics: vulnerable network, cybersecurity vulnerabilities, external pentest

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