Internal vs external penetration testing.

A secure IT infrastructure is fundamental to your organisation’s cyber security.
The financial, strategic and reputational cost of suffering a breach can be devastating.
So, it’s advisable to carry out regular internal and external penetration testing to flag up and address potential vulnerabilities.
In this article, you’ll learn what penetration (pen) testing is, with particular reference to internal and external pen testing.
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What is penetration testing?
Penetration testing or pen testing is when tests are carried out to try to penetrate a company’s systems. The aim is to find vulnerabilities that could be exploited internally or externally by cyber criminals.
Pen testing replicates techniques used by attackers and provides technical recommendations on how to fix each vulnerability, along with the potential impact each vulnerability could have if exploited.
Pen testing can be performed by internal testing teams or third-party consultants.
Obviously, there is great value in using third-party testing professionals – experience, expertise, unbiased opinions, thoroughness and up-to-date knowledge.
Types of network penetration testing.
Pen testing your network and infrastructure can be carried out from two perspectives or directions:
- Internal pen testing uncovers vulnerabilities that could be exploited internally.
- External pen testing identifies vulnerabilities that attackers could exploit on public networks to gain entry to your internal network and applications.
Internal network penetration testing.
Internal pen testing is carried out from within an organisation’s network. It can help to assess how far an attacker can laterally move through a network once inside the network (via an external breach).
It can pick up vulnerabilities and misconfigurations that could allow internal threats like disgruntled employees or business partners access to sensitive data and systems without authorization.
Additionally, internal pen testing can be used to highlight the potential spread of malware within internal systems, PCs, servers etc.
Internal pen testing is probably better suited to larger organisations. Those with a large number of employees, or that hold sensitive data internally, or those looking to meet regulatory standards, for example.
External network penetration testing.
External pen testing is performed from outside the organisation’s network. It’s designed to test the effectiveness of your perimeter(s) security.
For example, an external pen test might test:
- The network used by your website or application.
- Administrative features.
- Email platforms.
- File-sharing systems.
Pen testing specialists will use the latest attack techniques to simulate real cyber attacks, assessing internet-facing targets such as firewalls, FTP servers and network configurations, as well as encryption protocols, system vulnerabilities and network devices.
Importance of internal and external network penetration testing.
Both approaches to penetration testing complement each other and are essential to determine how vulnerable your systems are to attacks.
However, internal threats are rarer, whereas external threats are ever-evolving, more common and potentially more damaging to deal with. With external pen tests, organisations can focus more on their most prominent vulnerabilities.
Internal and external pen testing can help discover flaws in your cyber security program, and also validate your existing security policies and procedures.
Both types of pen tests are critical to keeping your network secure and should ideally be performed at least once a year.
There may also be other times when a pen test should be performed, for example:
- When your website, software or network are updated.
- As part of the software development cycle of an application.
- To comply with security requirements, standards, policies and procedures.
And finally…
The importance of external and internal penetration testing to an organisation cannot be underestimated. Whether conducted by an internal team or expert third-party consultants like BlueFort Security, penetration testing is a necessary tool to determine how vulnerable your systems are to cyber attacks.
With cyber attacks ever-evolving and on the increase, coupled with companies moving to a more flexible and remote-working culture, network and system vulnerabilities must be discovered and secured effectively.
If you need advice on penetration testing or have any other cyber security requirements, do get in touch. Just call 01252 9187000, email enquiries@bluefort.com or use our contact form here.

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