The Difference between Internal and External Pentesting

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Introduction

Since we explained what is pentesting and the purpose of it in a previous article, in this article we’ll see the difference between Internal and External Pentesting, why both are needed and what benefits your company would get from each one.

Penetration testing has different methods of execution. Depending on the type of pentesting, this assessment allows 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.

Penetration tests can be either external or internal depending on the goal of the project.

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?

Understanding the differences between internal and external penetration testing is important so that you can use the method that is best suited and properly evaluate the results.

Here, we’ll discuss internal vs external penetration testing, why each one is important and when you might need them.

Ideal Pentests use a specific framework and predetermined objectives so the Pentesters can find potential weaknesses, flaws and validate exposure within your internal or external infrastructure.

What is an External Penetration Testing?

It is crucial to comprehend the reasons behind conducting a Penetration Test. Are you driven by compliance demands or evaluating the security of a recent hardware/software upgrade? 

An external Penetration Test is an authorized assessment conducted from the perspective of an outside attacker against your organization’s publicly external IT infrastructure and exposed network services. It attempts to find and exploit vulnerabilities to review the chances of being attacked or compromised by mimicking the actions of an actual threat actor (or attacker). By exploiting the found vulnerabilities that could be found, such as open ports, outdated virus applications, and zero-day exploits it identifies the information being exposed to outsiders. As a result, the test will show whether the implemented security measures are enough to secure an organization and assess its capability to defend against any external attack.

The most common goal for an external Penetration test is to determine if it is possible for an attacker to gain an internal foothold into your organization’s network. However, the goal(s) are customized for each assessment based on your organization’s requirements.

An external penetration test is a service offering that should be used after your organization has attempted to harden your external perimeter via patching and secure service configurations, have sensitive information such as clients and payments, or want to check how your defensive systems react to such attacks. This service will validate the effort your organization has invested in and identify any areas that might need remediation.

What’s included?

External penetration testing includes:

• 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.
• Configuration and Deployment Management Testing
• Identity Management Testing
• Authentication Testing
• Session Management Testing, Input Validation Testing
• Testing for weak Cryptography
• Business Logic Testing
• Injection based attacks
• Denial of Service attempts on various services
• Client-Side Testing
• Testing for Error Handling.
• Reporting the findings so your organization can tackle remediation steps.

What is an Internal Penetration Testing?

Internal penetration testing looks at the security controls within your network. It’s the process of identifying and exploiting vulnerabilities in your own system and discovering who can get inside the network by hacking your network. It is also done, in order to test if rogue employees can perform attacks internally without any security mechanisms blocking them and what impactful it could have in terms of disclosure, misuse, alteration, or destruction of an organization’s confidential information. The internal penetration test is highly useful for organizations that want to know what could be accomplished by an attacker who has internal access to your network.

The internal penetration test should be conducted after your organization has attempted to secure your internal network and would like to ensure that your current security configurations and processes protect all internal infrastructure.
We need to note that the internal approach, which includes post-exploitation methodologies and bypassing measures, is not the same as the external. They do not use the same tools, which also means it requires different skill sets to perform. The idea of the internal is not only to find and exploit vulnerabilities of different types of devices that require a certain skillset and cannot be performed using automated tools. For example, You are after SmartTVs, Notebooks, Servers, Storage Devices, Network Printers, Security Cameras, Active Domains, and IoT devices. So you can understand that it all relies upon the knowledge and experience the provider has in this, and you want to create an impact by showing your clients what can take place and where to look for sensitive information within the organization.

What’s included?

Internal network penetration testing involves:

• Various mixed endpoints such as IoT (Network Printers, Security Cameras, SmartTvs, Smartphones (IOS/Android), Servers, Virtual and Physical, Notebooks, etc…
• Privilege escalation, malware spreading, man-in-the-middle attacks (MITM), credential stealing, monitoring, information leakage, or any other malicious activity.
• Identification of vulnerabilities on internal-facing assets such as applications.
• A simulated attack at these vulnerable points.
• Utilizing internal network scanning, exploiting, and firewall testing.
• Sniffing the internal network while checking what sensitive information can be stolen, decrypted, and cracked.
• Attempt to go deeper such as breaking into accounting, and backup storages to show the serious impact of what can be found from such deep dives.
• Reporting the findings so your organization can tackle remediation steps.

Pros and Cons

External Pentesting

Pros:

• Can identify vulnerabilities that are specific to the organization’s Internet-facing systems, such as web applications and network devices.
• Can test the organization’s ability to detect and respond to external threats.
• Can provide insights into how well the organization’s security measures are working against real-world attackers.
• Can help the organization prioritize its security investments based on the most critical vulnerabilities found.
• Can reveal the tracing of a company using OSINT and exposed files, and sensitive information that is forgotten or out of date. from past or current employees which will allow the organization to trace each one back and perform the necessary remediation.

Cons:

• May be less effective at identifying vulnerabilities in systems that are not accessible from the Internet, such as internal servers or applications.
• May produce false positives or negatives due to the difficulty of accurately simulating real-world attacks.
• May be limited by legal or ethical considerations, such as restrictions on testing third-party systems or conducting certain types of attacks.
• Employees of that organization are still vulnerable as their endpoints can be accessed through an external network while using the work device.

Internal Pentesting

Pros:

• Can identify vulnerabilities that are specific to the organization’s internal systems, such as internal servers, IoT smart devices, notebooks, and databases.
• Can test the organization’s ability to detect and respond to internal threats, such as insider attacks or malware infections.
• Can provide insights into how well the organization’s security measures are working from an internal perspective.
• Can help the organization prioritize its security investments based on the most critical vulnerabilities found.
• Will reveal to what extent an attacker can go – such as what sort of sensitive information he can exfiltrate ranging from accounting, emails, passwords but also financial and medical information of employees, and management which can be a damaging factor for the reputation.
• Can infect purposely ransomware and use Cyber Extortion to press for financial payments without guarantee.

Cons:

• May be limited by the organization’s security measures, such as firewalls or intrusion detection systems, that can prevent or detect attacks.
• May be more difficult to coordinate and execute than external pentesting, as it requires highly skilled Red Teams which require them to perform more complex attacks such as post-exploitation, evading techniques, and privilege escalations and many companies who use automated attacks will fail to achieve.
• May produce false positives or negatives due to the complexity of the organization’s internal systems and the difficulty of accurately simulating real-world attacks.

Which one is best for your Company?

Both External and Internal Pentesting are equally important but it depends on each company’s needs.

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.
• You have never tested your systems, and want to see what sort of coverage can be found from an external point of view.
• Seeking Compliance such as ISO 27001, PCI, DSS, etc…

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.

Conclusion

Cybercrime shows no signs of slowing down, and a Cyber-attack has the potential to incapacitate an organization. Cybercriminals are constantly scouring for new ways to use flaws and steal data.

As a company, while you add a budget for investing in defensive security measures such as firewalls, EDRs (Endpoint Detection and Response), XDR’s (Extended detection and response) and Intrusion Protection Systems (IPS), can provide a good foundation for security you should also consider to add a budget for investing in offensive security assessments in order to effectively safeguard against potential cyber threats.

It is crucial for an organization to implement a comprehensive security approach that encompasses both internal and external penetration testing. Whether the threat originates from external sources targeting sensitive personal data, or internal weaknesses that can be exploited, it is essential for the organization to be prepared and equipped to tackle all types of security incidents, intentional or unintentional.

Important Note: Beware of companies who offer automated assessments so you can utilize your budget better to get the maximum value out of it. Also, keep in mind that many of them will ask you to whitelist them because they do not have the knowledge to bypass firewalls and security measures – unlike real experienced hackers.

Be proactive, not reactive. Cybercriminals need just one flaw to strike.

Are you looking for a better way to secure your business? Whether you need a product audit, vendor security assessment, or overall security testing, we can help. Our team of experts will work with you to identify your specific security needs and provide tailored recommendations to improve your overall security posture.

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