What Is Internal Penetration Testing? A Practical Guide

Discover the importance of the Internal Pen Test to secure your network. Learn key strategies for effective testing in our latest blog.

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Internal Penetration Testing plays a crucial role in identifying vulnerabilities and protecting businesses against potential breaches. It is an essential step for organizations aiming to test the resilience of their existing internal network defenses. In this blog post, we will explore the various phases involved in internal penetration testing and highlight the importance of each.

Phase 1: Reconnaissance or Information Gathering to commence the internal penetration testing

Reconnaissance serves as the foundation of any security assessment. It enables Red-Teamers and Penetration Testers to gain a deep understanding of the target system and formulate an effective strategy for subsequent actions. In the context of internal network pentesting, a thorough understanding of the network becomes paramount. This leads us to the next phase.


Phase 2: Scanning and Enumeration – Gaining Network Visibility

Scanning involves interacting with network hosts to gather critical insights. Important questions need to be answered during this phase. Are the hosts operational? If they are, can we probe them to identify open ports, and running services, and determine the operating system in use?

To obtain answers to these questions, familiarity with scanning techniques is essential to fine-tune tools and obtain accurate results. When using NMAP, focusing on timing and performance scanning options, such as the recommended T4 timing template for internal scans, can significantly enhance efficiency. However, customization based on specific requirements is still advisable.

Upon completion of the scanning phase, it is crucial to document all findings and collaborate with consultants to develop a targeted strategy for the subsequent phase, vulnerability identification.

What should be done if port 149 or port 445 is discovered during a Nmap scan? Further enumeration is required.

Moreover, encountering an Intrusion Detection System (IDS) or a Firewall presents additional challenges. How can one effectively navigate such obstacles?

Phase 3: Vulnerability Scanning – The Blend of Manual and Automated Approaches for your internal pen test

Once all relevant network information has been gathered in previous phases, vulnerability scanning becomes the next logical step. Several tools, including OpenVas and Nessus, can be employed for this purpose.

During a recent client engagement, we encountered a port used for Real-Time Streaming Protocol (RTSP). While tools and scripts existed to probe this port, we discovered that manual testing proved crucial in successfully advancing to the next phase: exploitation.

Phase 4: Exploitation – A Tricky Endeavor

Exploitation is a phase where conventional exploitation tools might fall short in exploiting vulnerabilities. In such cases, it may be necessary to develop custom exploits with minimal test cases to prove their effectiveness. Our experience with RTSP exploitation highlighted the importance of this approach.

It is worth noting that, in certain cases, simulating an attack that originates from within the network may warrant data exfiltration attempts, subject to client authorization.

Phase 5: Reporting and Quality Assurance

Thorough documentation of all steps taken is paramount, as it serves as the foundation for creating a comprehensive final report. This report should include an executive summary that presents findings in a manner that enables C-level and D-level executives to fully grasp the impact of the assessment. Quality assurance teams play a critical role in ensuring the delivery of assessments with the highest level of quality.

For organizations considering internal pen tests, it is crucial to define the scope, testing timeline, and rules of engagement before conducting the pentest.

Most importantly, engaging experienced consultants is vital to successfully navigate the intricacies of internal penetration testing. If you are seeking a capable team for your internal penetration testing needs, you have come to the right place.

 At Bluefire Redteam, we execute over 50 internal pen tests annually, covering more than 20 IP ranges simultaneously. Schedule a hassle-free internal pen testing engagement with us today and fortify your network defenses!

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