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Internal penetration testing is essential for assessing the security of a company's internal network. It involves ethical hackers simulating cyber-attacks to identify weaknesses within network infrastructure, systems, and applications. This testing contrasts with external penetration testing, which focuses on external threats and vulnerabilities. An internal pen test primarily aims to prevent malicious insiders or external attackers who have gained unauthorised access from exploiting internal vulnerabilities.

Table of Contents

1. What is Internal Penetration Testing?
2. Goals and Objectives of Internal Pen Testing
3. Internal vs. External Penetration Testing: A Comparison
4. How to Plan an Internal Penetration Test
5. Legal and Ethical Considerations in Internal Pen Testing
6. Executing Internal Penetration Tests
7. Analysing and Reporting in Internal Penetration Testing
8. Remediation Strategies Post-Internal Penetration Testing
9. Best Practices in Conducting Internal Penetration Tests
10. Common Pitfalls in Internal Penetration Testing and How to Avoid Them
11. Conclusion

In the discovery phase of an internal penetration test, pen testers scrutinise various components such as operating systems, network services, and access controls. This phase is crucial for identifying security gaps and preparing for deeper exploration. Internal pen testing also assesses security controls, aiming to detect privilege escalation opportunities and security flaws. This process helps in safeguarding sensitive systems and data, ensuring robust network security.

During an internal network penetration test, testers may employ techniques like targeted testing, blind testing, or double-blind testing. These methodologies help in uncovering vulnerabilities in critical elements like web applications, sensitive information storage, and access management systems. By identifying and addressing these security holes, Australian organisations strengthen their security posture against future attacks, data breaches, and insider threats.

What is internal penetration testing?

Internal penetration testing, an indispensable component of cybersecurity, entails the simulation of cyber-attacks within a company's internal network to uncover vulnerabilities. Unlike external penetration testing, which evaluates the security of externally facing IT assets like websites and network services, internal testing delves deep into the internal network. The focus is on identifying and mitigating potential security risks that exist within the confines of the organisation.

This process involves a thorough examination of network infrastructure, access controls, sensitive data storage, and internal communication channels. The objective is to pinpoint and resolve internal weaknesses before they can be exploited by malicious actors. By proactively addressing these vulnerabilities, internal penetration testing plays a crucial role in preventing data breaches and enhancing the overall security posture of the organisation.

Goals and objectives of internal pen testing

The primary goals of internal penetration testing centre on identifying and addressing vulnerabilities within a company's internal network. This strategic approach in cybersecurity, conducted by skilled pen testers, is crucial for enhancing a business's overall security posture. Internal pen tests aim to uncover security gaps and weaknesses in network infrastructure, operating systems, and access controls. By simulating cyber-attacks, internal penetration tests provide insights into how malicious insiders or external attackers might gain unauthorised access, thereby exposing security flaws and potential data breaches.

Additionally, internal pen testing helps businesses safeguard sensitive data and comply with regulatory standards like PCI DSS. Through various testing methodologies, including targeted, blind, and double-blind testing, pen testers scrutinise network services, web applications, and sensitive systems. This comprehensive approach ensures that internal networks are robust against a range of attack vectors, from insider threats to external cyber-attacks. Effective internal penetration tests not only identify and mitigate immediate security risks but also contribute to long-term risk management and resilience against future attacks.

Internal vs. external penetration testing: A comparison

Internal and external penetration testing, though similar in objective, differ significantly in focus and methodology. External penetration tests evaluate the security of publicly accessible assets, such as websites and external network services, to identify vulnerabilities that could be exploited by attackers from outside the organisation. This form of testing is critical for detecting potential entry points for cyber-attacks and ensuring that external defences are robust.

In contrast, internal penetration testing concentrates on the risks and vulnerabilities within a company's internal network. It simulates scenarios where an attacker has already gained access to the internal network, either through a breach or as a malicious insider. This testing is crucial for understanding how an attacker could move laterally within the network, escalate privileges, and access sensitive data. Internal tests assess the strength of internal security controls and the ability of the network to withstand attacks from within. Both testing types are essential for a comprehensive cybersecurity strategy, addressing different aspects of an organisation's security posture.

How to plan an internal penetration test

Planning an internal penetration test can be structured into the following numbered steps for clarity and effectiveness:

1. Define the Scope: Determine which parts of the internal network, systems, and applications will be included in the test. This step helps focus the testing efforts on specific areas.

2. Set Objectives: Establish clear goals for the test. Identify the primary security concerns and the specific vulnerabilities you aim to uncover.

3. Understand the Network Landscape: Gain a comprehensive understanding of the network's architecture, including potential entry points for attackers. This knowledge is crucial for a thorough assessment.

4. Choose the Testing Methodology: Decide on the approach for the test, such as targeted testing of particular systems or a broad examination of various network segments.

5. Select Testing Techniques: Choose the techniques to be used during the test, which could include social engineering, network scanning, or attempts to bypass security controls.

6. Align with Legal and Organizational Requirements: Ensure all testing activities comply with legal requirements and organisational policies. Obtain necessary approvals and keep relevant stakeholders informed.

By following these steps, the planning process for an internal penetration test becomes structured and easier to manage.

Legal and ethical considerations in internal pen testing

When conducting internal penetration testing, legal and ethical considerations must be prioritised. It's essential to obtain explicit permissions from all relevant authorities to ensure compliance with legal frameworks. Respecting privacy laws and data protection regulations is also critical to maintaining ethical standards. Additionally, tests should be carefully designed and executed to minimise disruptions to normal business operations, ensuring that daily activities are not adversely affected. This responsible approach safeguards the organisation's legal and ethical integrity while conducting these crucial security assessments.

Executing internal penetration tests

Reconnaissance and discovery

In the Reconnaissance and Discovery phase of internal penetration testing, testers use network scanning and vulnerability assessment tools to systematically identify potential security weaknesses. This crucial step involves analysing the network’s structure and pinpointing critical assets, effectively mapping the attack surface to prepare for further testing stages.

Exploiting vulnerabilities

In the Exploiting Vulnerabilities phase, once potential weaknesses are pinpointed, testers actively try to exploit these vulnerabilities. This critical step helps in gauging the extent of potential damage and data breach risks. By simulating attacks, testers can assess how deep an actual breach might penetrate and what sensitive data could be compromised. This phase is vital for understanding the real-world implications of identified security gaps.

Internal penetration testing tools and techniques

Internal Penetration Testing relies heavily on a range of specialised tools and techniques. Key among these are Metasploit and Nmap, which are essential for effective testing. Metasploit facilitates the exploitation of identified vulnerabilities, while Nmap excels in network scanning and mapping. Together, they enable comprehensive vulnerability scanning, effective exploitation, and detailed post-exploitation analysis. This synergy of tools and techniques ensures a thorough assessment of the network’s security posture.

Advanced techniques in internal penetration testing

Advanced techniques in internal penetration testing, such as Kerberoasting, play a crucial role in identifying and exploiting specific vulnerabilities. These sophisticated methods delve deeper into the nuances of internal network security. Kerberoasting, for example, targets weaknesses in Kerberos authentication, revealing how attackers could exploit these flaws to gain unauthorised access. Such advanced tactics provide invaluable insights into the more intricate aspects of network security and potential breach points.

Simulating attacks in internal penetration testing

In internal penetration testing, simulating a variety of cyberattacks is a pivotal process. This simulation helps in thoroughly assessing the network's defences, revealing how they would stand up against actual real-world attacks. By replicating various attack scenarios, from phishing to advanced persistent threats, testers can evaluate the effectiveness of current security measures. This exercise is critical in identifying weaknesses and reinforcing the network's resilience against potential cyber threats.

Types of internal penetration testing

Black Box Testing

Black Box Testing is a methodology where testers, simulating the role of an external attacker, conduct tests without any prior knowledge of the target network's infrastructure. This approach is crucial for understanding how an outside intruder might penetrate the system. By operating with the same information limitations as a real-world attacker, testers can uncover vulnerabilities that might be exploited by someone without insider knowledge of the network, thus providing a realistic assessment of the network's external security posture.

Grey Box Testing

Grey box testing represents a middle ground in penetration testing methodologies, providing testers with limited knowledge of the system under scrutiny. This approach combines elements of both black and white box testing. Testers, equipped with some insights about the network's internal workings, can more effectively target specific areas, making this method efficient for identifying vulnerabilities that might be overlooked in purely external or internal testing scenarios. It offers a balanced perspective, reflecting a semi-informed attacker's view of the system.

White Box Testing

In white box testing, testers are equipped with complete knowledge of the network infrastructure, including access to source codes and network diagrams. This enables a thorough and detailed security assessment, covering all aspects of the system's vulnerabilities and strengths.

Analysing and reporting in internal penetration testing

Post-internal penetration test, analysis and reporting findings is crucial. This includes reviewing results to identify vulnerabilities, compiling detailed reports highlighting these issues, and providing actionable remedial recommendations. These reports are vital for stakeholders to address security weaknesses and enhance overall defence strategies, thereby fortifying network security.

Remediation strategies post-internal penetration testing

Post-internal penetration testing, remediation strategies are key. This involves more than patching identified weaknesses; it requires enhancing the overall security framework to prevent future breaches. Actions include updating protocols, strengthening network defenses, and staff training, transforming test insights into concrete security improvements, equipping the organisation against future cybersecurity challenges.

Best practices in conducting internal penetration tests

Adhering to best practices in conducting internal penetration tests is vital for ensuring effectiveness, ethical integrity, and organisational benefit. This includes obtaining proper authorisation, defining clear objectives and scope, using updated and reliable testing tools, and maintaining transparent communication with relevant stakeholders. Additionally, it's important to respect data privacy laws and ensure minimal disruption to normal operations. Following these guidelines guarantees a responsible, comprehensive, and insightful testing process, leading to significant improvements in the organisation's cybersecurity measures.

Common pitfalls in internal penetration testing and how to avoid them

Common pitfalls in internal penetration testing, like inadequate planning and overlooking emerging threats, can be avoided with thorough preparation, and staying informed about new cybersecurity trends. Continuously updating strategies and methodologies is crucial for organisations to effectively prepare for future challenges. Regular training and adapting to evolving threats are key to maintaining robust cybersecurity defences.


Internal penetration testing stands as a cornerstone of modern cybersecurity, playing a pivotal role in maintaining continuous vigilance and strengthening an organisation's defence against internal threats. The practice of regular testing, coupled with the adaptation to new and emerging challenges, is essential for any organisation seeking to uphold a robust and resilient defence mechanism. This proactive approach not only addresses current security concerns but also prepares the organisation to effectively counter future cybersecurity threats, ensuring a secure and stable digital environment.

Frequently asked questions

What are the three types of penetration tests used on an internal network?

Three types of penetration tests are internal, targeting an organisation's internal network for security gaps, external, assessing defences against outside threats, and web application, focusing on uncovering vulnerabilities in web-based software and code.

Should internal audit perform penetration testing?

Yes, internal audit teams can perform penetration testing, especially internal pen tests. This practice is crucial for identifying and mitigating internal vulnerabilities and ensuring robust network security. However, it is often beneficial to have an independent pen tester or external team conduct these tests to provide an unbiased perspective and uncover issues that internal teams might miss.

What is an internal pen test?

An internal pen test simulates cyber-attacks on an organisation's internal network to identify and exploit security weaknesses. It aims to prevent data breaches by understanding potential unauthorised access and privilege escalation, thereby safeguarding sensitive data and ensuring network security.

What are the five internal network penetration test techniques?

The five key network pen testing techniques are port scanning, vulnerability scanning, password cracking, packet sniffing, and social engineering. Port scanning identifies open ports and services available on the target system. Vulnerability scanning detects security holes in systems and network infrastructure. Password cracking tests the strength of password policies. Packet sniffing monitors network traffic for vulnerabilities. Social engineering evaluates the human factor in security, testing susceptibility to phishing and other deceptive tactics that could lead to unauthorised access.

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