What is Internal Penetration Testing?

Securing not just your external IT environment, but also your internal networks and applications is crucial to prevent breaches. While external penetration tests have become standard practice, compliance with the Payment Card Industry Data Security Standard (PCI DSS) also necessitates the lesser-known internal penetration tests.

These internal pen tests should be conducted at least annually and following any significant modifications or upgrades to applications or infrastructure.

Internal Pen Testing Needs to be Standard Practice

External penetration tests identify potential breaches from outside, such as attacks on exposed web applications. In contrast, internal penetration tests simulate an attack from within your organization’s internal networks and applications, assessing the potential impact. There are two primary internal cyber-attack patterns:

Malicious Insider: An attack by a malicious individual with access to your Ethernet network, internal server, or even a workstation can be particularly devastating, especially if the attacker already knows where sensitive information is stored. Internal pen testing is essential to identify vulnerabilities to such insider attacks.
Software Vulnerabilities: The release of a new application and its interaction with operating systems and processes can introduce security holes. Internal pen tests expose vulnerabilities due to improper software and hardware configurations or weak application perimeter defenses. Since new software installations and system configuration changes alter the entire system environment, scheduled internal penetration tests are crucial for maintaining robust IT security.

Common situations involving individuals with insider access or application updates pose significant security risks. Therefore, routine internal pen testing should complement external pen tests to strengthen your overall security posture.

Even SAP users of shared business-critical applications – such as Enterprise Resource Planning (ERP), Human Capital Management (HCM), and Supply Chain Management (SCM) – frequently encounter security gaps. These gaps often result from a lack of visibility in SAP and uncoordinated internal security procedures without proper strategies. Thus, routine internal penetration tests are highly recommended for SAP users.

Another potential scenario involves an attacker compromising a server in your cloud environment and exploiting a communication channel (e.g., VPN tunnel) between the cloud and your network. This could serve as an entry point for the attacker into your internal network.

Importance of Internal Pen Testing

Internal penetration tests are crucial for identifying vulnerabilities within your network infrastructure. They simulate real-world attacks from malicious insiders or hackers who have gained access to your internal network. By employing ethical hacking methodologies, testers can uncover security vulnerabilities that could be exploited by attackers. This includes evaluating security controls and the overall security posture of your network.

Network penetration tests, whether internal or external, should be part of a comprehensive security testing strategy. They help identify vulnerabilities, assess the effectiveness of security controls, and ensure the resilience of your network infrastructure against potential exploits. Regular internal pen tests are vital for sustaining robust cyber security and protecting your organization from both internal and external threats.

Types of Pentest: Internal vs. External Penetration Testing

Internal Penetration Testing

Internal penetration testing involves assessing the security of your infrastructure by attempting to breach it from within. This type of testing can be performed either by an internal party, such as an employee of the company, or an external party hired specifically for this purpose. The primary objective of an internal penetration test is to determine what an attacker could achieve if they had initial access to your internal network.

An internal party, someone already working for the company, conducts the test with the advantage of understanding the internal environment and its nuances. Alternatively, an external party might simulate an initial access scenario to further probe internal network security.

The results of an internal penetration test are crucial for establishing a baseline of your network’s security posture, identifying vulnerabilities, and understanding the potential impact of an insider or a compromised internal system. This test helps in evaluating how well your internal defenses can withstand an attacker who has already bypassed the external perimeter.

External Penetration Testing

External penetration testing, often referred to as External Penetration Testing, evaluates the security of your network from an outside perspective. This type of testing focuses on identifying vulnerabilities that could be exploited by attackers who do not have initial access to the internal network.

External penetration tests are typically conducted by third-party security professionals who are not involved in designing, implementing, or maintaining the organization’s network infrastructure or systems. These tests aim to assess the effectiveness of perimeter security controls, including network devices, network ports, firewalls, and web applications.

The primary goal of external penetration testing is to determine the robustness of your external defenses against potential attacks. By simulating real-world attack scenarios, external pen testers can identify security weaknesses and provide recommendations to strengthen your network’s perimeter defenses.

Key Differences:

Scope:

Internal Penetration Testing: Focuses on internal network infrastructure and the potential impact of insider threats or compromised internal systems.
External Penetration Testing: Concentrates on external-facing components and the effectiveness of perimeter security controls.

Execution:

Internal Penetration Testing: Can be performed by internal staff or an external party simulating internal access.
External Penetration Testing: Conducted by third-party professionals not involved in the internal network’s setup or maintenance.

Objective:

Internal Penetration Testing: Establishes a security baseline and identifies vulnerabilities from an insider’s perspective.
External Penetration Testing: Evaluates the external security posture and identifies vulnerabilities that could be exploited from outside the network.

By conducting both internal and external penetration tests, organizations can achieve a comprehensive assessment of their network security, addressing vulnerabilities from both internal and external threats.

How Internal Penetration Testing Works

Internal Networks and Applications

Internal network penetration testing involves collecting detailed information about the network and applications using ‘white box’ techniques. This method allows penetration testers to identify potential security weaknesses through DNS queries and traffic analysis. Before executing any attacks, a comprehensive vulnerability assessment is performed.

The next phase involves exploiting the identified weak spots to gain unauthorized access to active directories, databases, web applications, and network services. Pen testers simulate a real breach scenario to locate the organization’s critical assets, such as social security numbers, electronic payment card numbers, employee personal information, and proprietary information. This demonstrates the potential devastation of an insider attack. A detailed test report is then provided, highlighting any vulnerabilities that need to be addressed.

Internal Pen Testing Your Cloud Environment

Internal network penetration tests for in-house infrastructure can be conducted by a highly skilled internal security team or a trusted third-party service. However, internal network penetration testing in a cloud environment presents unique challenges. Many Cloud Service Providers (CSPs) do not permit pen testing due to the risk it poses to the security of other tenants on their multi-tenant platforms.

Alternatives for Internal Pen Testing in Cloud Environments:

Negotiate with CSPs: Obtain permission from your CSP to perform an internal network penetration test, though this may limit the scope of testing for internal applications and data.
Review CSP Test Results: CSPs often conduct their own cloud pen tests to comply with security standards. You can request copies of these results and related technology audit reports to consolidate with your own internal network penetration tests.
Pivot Attacks: A penetration tester can exploit a system or application and use it as a pivot point to launch further test attacks on other applications and systems. This approach simulates an insider’s perspective and is usually permitted by CSPs offering Platform-as-a-Service (PaaS) and Infrastructure-as-a-Service (IaaS) models. However, pen testing Software-as-a-Service (SaaS) models can affect configurations, so CSPs with SaaS may not allow pen testing. Therefore, pen testers must take extra care to avoid violating CSPs’ terms and conditions while exploiting their own IPs, ports, instances, and applications.

Internal Network Penetration Testing Methodology

Information Gathering: Use ‘white box’ techniques to collect detailed information about the internal network and applications.
Vulnerability Assessment: Identify security weaknesses through DNS queries, traffic analysis, and other testing tools.
Exploit Phase: Execute attacks to gain internal access to critical systems, mimicking a malicious insider.
Impact Analysis: Demonstrate the potential impact of a breach by targeting sensitive information.
Reporting: Provide a detailed report highlighting vulnerabilities and recommendations for remediation.

By integrating internal network penetration tests with external pen tests, organizations can ensure a comprehensive assessment of their network security, thereby strengthening their overall information security posture against both internal and external threats.

Benefits of Internal Penetration Testing

Today, while many businesses are bolstering their defenses against external threats, they often overlook that 49% of cyber attacks originate from within. Internal breaches can be significantly more devastating than external threats because they exploit the inherent trust within the organization. This is why internal penetration testing is becoming increasingly essential.

Internal penetration testing involves simulating an attack from an insider, focusing on analyzing the network infrastructure for vulnerabilities, evaluating access controls, and testing the security controls of applications and databases.

Here are some key benefits of performing internal penetration tests:

Identify Internal Vulnerabilities: Internal pen testing helps uncover security weaknesses within your network infrastructure that might be overlooked by external assessments.
Uncover Insider Threats: By simulating an attack from within, internal pen tests can identify potential threats posed by malicious insiders or compromised internal accounts.
Thorough and Extensive Testing: Internal penetration tests provide a comprehensive evaluation of your internal security posture, covering various aspects of your network and applications.
Save the Cost of a Data Breach: By identifying and mitigating vulnerabilities before they can be exploited, internal pen testing can help prevent costly data breaches and the associated financial and reputational damage.
Achieve Compliance: Many regulatory standards require regular security testing. Internal penetration testing helps ensure compliance with these requirements, demonstrating your commitment to maintaining a secure environment.

Internal penetration testing is crucial for identifying and addressing vulnerabilities within your organization, thereby enhancing your overall security posture and protecting against both internal and external threats.

Conclusion

In conclusion, while external threats are a significant concern, the potential devastation from internal attacks necessitates robust internal penetration testing.

By identifying and mitigating internal vulnerabilities, uncovering insider threats, and ensuring comprehensive security evaluations, businesses can significantly strengthen their defenses. Internal pen testing not only helps in preventing costly data breaches but also ensures compliance with regulatory standards.

As cyber threats continue to evolve, incorporating regular internal penetration tests into your security strategy is essential for maintaining a secure and resilient IT environment.