External Penetration Testing 101 : A Beginner’s Introduction

Greetings, Cyber Enthusiasts!

Over the past two years, my journey in cybersecurity has unfolded, leading me to explore networking fundamentals, web application pentesting, and Active Directory penetration testing. Amidst this exploration, the term “External Penetration Testing” often crossed my path, fueling my curiosity.

Img: Figuring it Out

During my early days as a novice (still navigating the learning curve), I scoured numerous blogs and articles attempting to understand External Penetration Testing, but the concept eluded me. Recently, while freelancing in real-world engagements, I had the opportunity to immerse myself in this aspect of cybersecurity. Today, with a bit more experience under my belt, I find myself in a position to share foundational knowledge with beginners.

This introduction merely scratches the surface, with subsequent blogs set to explore the tools and techniques integral to External Penetration Testing.

If you’re eager to delve deeper into External Penetration Testing, I recommend exploring a course that will assist you in getting started and gaining practical experience. I’d like to highlight TCM Security’s External Pentest Playbook as an excellent resource for beginners to immerse themselves in this field and gain valuable insights

Let’s get Started!!!

External Penetration Testing : An Introduction

So what is a external penetration testing ?

It's a simulated cyber-attack where a hacker tries to hack into an organization from outside of that organization’s Network.

Img: External Pentesting Basic Example

The goal is to identify and address vulnerabilities before real hackers can exploit them, ensuring a robust defense against potential cyber threats.

Objectives of an External Penetration Test

The Objectives of an external penetration test are as follows:

1. Spot Weak Points: Find any possible weak spots in the systems, networks, and apps that are accessible from the outside.
2. Check Security Tools: Test if the security tools in place, like firewalls and access controls, are doing a good job at keeping unauthorized users out.
3. Act Like Real Hackers: Pretend to be hackers in a controlled way to see how well the current defenses can handle and respond to potential attacks from external sources.
4. Test Emergency Response: See how well the organization can detect, respond, and recover from security incidents, including how fast it can handle potential breaches.
5. Follow the Rules: Check if the organization is following the rules and standards set by regulators and the industry regarding cybersecurity.
6. Give Useful Advice: Provide practical suggestions and tips to make the overall security better, helping the organization fix any problems and stand up better against outside threats.

External Penetration testing Methodology

External Penetration testing typically follows a structured methodology. while specific Technologies may vary, a common approach often involves the following stages:

1. Information Gathering and OSINT : Gathering Information about the target organization, such as it’s IP addresses, Domain Names and other publicly available details.
2. Scanning : scans the target’s external infrastructure to discover live hosts, open ports, and services. This process helps create a map of the organization’s external attack surface.
3. Enumeration: Once potential targets are identified, the tester seeks to gather more detailed information about the users. This step helps in preparing for the actual testing phase.
4. Vulnerability Analysis: The tester analyzes the collected information to identify potential vulnerabilities in the target systems. This may involve using automated tools to assess common vulnerabilities and weaknesses. For example, Nessus.
5. Exploitation: In this phase, the tester attempts to attack the services which are facing externally like SSH, RDP, Telnet Etc. Tester also tries password spraying against enumerated users to gain initial access through Web login Portals like Outlook Web Access (OWA), M365, Google Suite etc.
6. Post-Exploitation: If successful, the tester may perform post-exploitation activities to understand the extent of the compromise, identify sensitive data, and assess the organization’s ability to detect and respond to the breach.
7. Reporting: The tester compiles a detailed report outlining the findings, including identified vulnerabilities, the level of risk they pose, and recommendations for remediation. The report aims to provide actionable insights for improving the organization’s security posture.
8. Cleanup and Documentation: After completion of the test, the tester works with the organization to clean up any changes made during the testing process and provides comprehensive documentation of the testing methodology, results, and recommendations.

This concludes the introductory segment on external penetration testing. By now, I trust you have gained a solid understanding of what external penetration testing entails, along with its objectives and methodologies.

In the upcoming blog, we’ll delve into the first two crucial steps of the external penetration testing methodology: Information Gathering/OSINT and Scanning External Infrastructure. I am excited to shed light on these essential aspects to further enrich your knowledge in the field.

If you enjoyed this blog, please consider giving it a clap to motivate me to create more content. If you found value in what you’ve learned, don’t keep it to yourself — share it with others. Let’s spread the knowledge so that as many people as possible can benefit from these insights.

Thank you for your engagement and curiosity!

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