External vs Internal Penetration Testing

External and internal penetration testing are methods used to test an organisation’s cyber security. External testing simulates attacks from outside the network, while internal testing assumes an attacker already has access. Together, they help identify how an attacker could get in and what they could do once inside.

Used together, these tests provide a clear and realistic picture of your real-world security risks.

External testing answers a critical question: “What can an attacker do from the outside?”

It focuses on the parts of your systems that are accessible from the internet. This includes websites, servers, email systems, VPNs and cloud services.

The goal is to identify vulnerabilities that could be exploited by someone with no internal access.

During an external test, security specialists will:

Internal testing answers: “If someone gets in, how much damage could they do?”

Internal penetration testing assumes the attacker already has some level of access to your internal network.

This could represent:

Internal testing focuses on how far an attacker could move once inside. Giving you an idea of how quickly and how much damage could be done.

An internal penetration test may include:

In the majority of cases the answer is yes.

External testing shows how attackers might get in. Internal testing shows what happens after they do.

Many real world breaches start with a small external weakness and then escalate internally. Without internal testing, these risks often go unnoticed.

Running both types of penetration testing provides better visibility of real attack paths and gives clear, actionable security improvements.

External and internal penetration testing address different parts of a real-world attack. Looking at both helps build a clearer picture of where vulnerabilities exist and how risks could develop across a network.

If you’d like to understand more about our penetration testing services, our team is always happy to help.