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Differences Between Internal and External Penetration Testing


The global average cost of a data breach is $3.86 million.

A financial services employee has access to 11 million files

A cyberattack occurs every 39 seconds. 

These statistics can scare any organization. It is no wonder that global cybersecurity spending has increased multifold in recent years. There are prevention techniques and proactive approaches that security professionals can apply to protect organizations from such risks.

At Packetlabs, we understand the importance of cybersecurity to the operation of any organization and the costs of a potential breach. We identify and recommend many measures and tactics to support and improve our client’s security posture. Regular penetration testing is an essential and effective tactic to include in any cybersecurity management plan.

Our blog last year on ‘External Penetration Testing vs. Internal Penetration Testing’ touched upon some key aspects of this subject. In this blog, we go in-depth into some of the key differences between the two. 

There are two paths a business could take: Internal penetration testing or external penetration testing. An internal network pen test is meant to gauge the severity of a potential hacker with access to the internal network. It mirrors an attack from within the organization, such as by an employee. An external penetration test searches for weaknesses in internet-facing assets like email, the web, and FTP servers. This test is usually conducted from the perspective of an attacker without prior knowledge of the organization.

Internal vs. Remote Threat

The main difference between an internal and external penetration test is the type of attack they test for. Internal testing assesses internal networks and uncovers vulnerabilities that could be exploited internally by malicious employees or business partners. Internal testing is also used to determine the potential spread of malware within internal systems. 

For example, a tester will have the same access someone from inside the organization would have. It can help the testers understand how much damage a malicious employee could conduct should they attack or spread malware. External penetration test seeks to identify vulnerabilities that attackers could exploit on public networks, such as the network used by the website or application. Administrative features are usually the most targeted areas, along with messaging platforms and file-sharing systems, often presenting critical vulnerabilities that allow attackers to access sensitive data. An external penetration test can take anywhere from a few days to a few weeks, depending on the complexity of the application, system or network. External testing is different from internal testing because it’s simulating an attack from an outside force, who’s accessing sensitive information remotely. Internal penetration testing includes privilege escalation, malware spreading, man-in-the-middle attacks (MITM), credential stealing, monitoring, information leakage or any other malicious activity.

Priority Testing

An external penetration test’s scope is based on the number of live hosts on the system’s perimeter (an IP address with at least one open port), so pricing can vary. Similarly, an internal penetration test is also scoped based on the number of live hosts on the internal network. This type of assessment can range roughly between $5,000 and $15,000. Therefore, internal penetration testing is usually a more expensive option, given the significant increase in the area attacked and the difference in the methodology used. 

Business Objective and Industry Type

Considering the higher costs and low priority, most organizations don’t think internal testing as valuable as external; this might be the case most of the time, but context is important. At Packetlabs, we have the expertise to help you decide what type of test is best for your particular institution and situation. 

Organizations dealing with large amounts of sensitive data may want their software secured from both internal and external threats for legal and business reasons. Disgruntled employees can cause enormous harm to a corporation, and one of the main functions of penetration testing is to ensure security from both internal and external threats. 


Ideally, an organization should conduct both internal and external penetration testing and other measures that ensure a strong cybersecurity posture. Whether it is personal data, which is often the target of external intruders or weak internal systems, which can collapse at the slightest threat, your organization needs to be prepared for most kinds of threats, if not all, which may happen intentionally or unintentionally. 

At Packetlabs, through our penetration testing services, we evaluate the security of your IT systems through a simulated cyber-attack conducted by a qualified team with experience and advanced training. If you have more questions about external and internal penetration testing, contact us today!