How I Work with External, Internal, and Assume-Breach Testing to Show How an Attacker Can Get In and Move Further

When I work with penetration testing, I think it is important not to get stuck in only one part of the attack surface. An attacker rarely thinks in isolated silos. That is why I also want to test the environment in a way that shows how a real attack chain could look.

This is where external testing, internal testing, and assume-breach scenarios become especially valuable. Together they give a much clearer picture of how well the organization can resist both an initial intrusion and continued movement inside the environment.

External tests show what an attacker meets first

In an external penetration test, I begin where an outside attacker begins: with internet-facing systems. I look at which systems, services, and applications are exposed externally and how they behave from the outside. I want to understand which opportunities an attacker has to gain an initial foothold, exploit weak points, or disrupt the business.

Internal tests show how far an attacker can go

Once someone has gained access, the next question is extremely important: what happens next? That is where internal penetration testing becomes critical. Here I begin inside the infrastructure and examine how easy it is to move laterally, escalate privileges, reach other systems, or exploit weak segmentation and weak identity management.

Assume breach makes security work more realistic

I like the assume-breach approach because it starts from a very useful idea: what happens if the attacker is already inside? This is especially valuable when a customer wants to test a specific concern, such as leaked VPN credentials, an insider scenario, compromised supplier access, a successful phishing attack, or another route in which the first layer of defense has already been bypassed.

I look at identity, segmentation, and trust between systems

These kinds of tests often reveal how much risk is created by overly broad trust relationships, weak privilege boundaries, or insufficient separation between systems and roles.

I want to show the attack chain, not only isolated findings

I think these tests are most valuable when they show how separate weaknesses can be linked together into a realistic attack path. That gives the customer a much more concrete understanding of risk.

I want recommendations that reduce the impact of the next intrusion

The goal is not only to show what is possible. The goal is to help reduce the consequence of the next real intrusion by improving segmentation, access control, privilege handling, monitoring, and recovery capability.

That is how I want to work with external, internal, and assume-breach testing: realistically, methodically, and in a way that gives the customer a better picture of both initial exposure and lateral risk.