Mastering Black Box Penetration Testing with TryHackMe

Mastering Black Box Penetration Testing with TryHackMe

Table of Contents:

1. Introduction
2. Objective of the Penetration Testing Challenge
3. Preparing for the Penetration Test
   • Briefing and Scope of Work
   • Understanding the Black Box Testing Methodology
4. Scanning the Open Ports and Services
   • Conducting an Nmap scan
   • Analyzing the results
5. Exploring the SMB Server
   • Attempting Anonymous Access
   • Accessing Shared Folders
   • Obtaining User Credentials
6. Remote Desktop Access
   • Using PsExec to log in
   • Troubleshooting username and password issues
7. Exploring the Web Server
   • Analyzing the HTTP server running IIS
   • Interacting with Port 4963
   • Uploading and Executing Files
8. Leveraging Reversal and Gaining Control
   • Understanding the potential of SMB shares
   • Creating and executing a reverse shell
9. Conclusion
10. Recommendations and Reporting

Article:

Introduction

In the world of cybersecurity, one of the most effective ways to identify vulnerabilities and assess the overall security posture of a system is through penetration testing. This article delves into a specific challenge from TryHackMe, a platform that offers hands-on cybersecurity training, focusing on a black box penetration testing Scenario. By following this step-by-step guide, You'll learn how to approach and overcome various obstacles, ultimately rooting the machine and writing a report for the client.

Objective of the Penetration Testing Challenge

The goal of this penetration testing challenge is to simulate a real-life scenario where you are tasked with exploiting a machine. Your objective is to find both the user flag and the root flag, proving that you successfully compromised the system. The challenge provides you with limited information and only a briefing about the engagement, making it a truly black box test. While writing a report is not mandatory, it is highly encouraged to develop your skills and provide valuable insights to the client.

Preparing for the Penetration Test

Before diving into the testing process, it's crucial to understand the scope of work and familiarize yourself with the black box testing methodology. The briefing provided gives you an overview of what is expected and the boundaries within which you can operate. This realistic scenario aims to simulate a real-world penetration testing engagement, ensuring that you Apply techniques used by professional penetration testers.

Scanning the Open Ports and Services

To kick-start the penetration test, the first step is conducting an Nmap scan. This scan is split into two parts: scanning for open ports and scanning for the versions of services running on those ports. By analyzing the results, you can gain insights into potential entry points and vulnerabilities.

Exploring the SMB Server

One of the open ports discovered during the scan is the SMB server. Attempting to access it without any credentials may grant you anonymous access. By interacting with the shared folders, you may stumble upon valuable information. In this case, logging in as "Alice" grants access to a file named "passwords," containing encoded strings that need to be decoded.

Remote Desktop Access

With the obtained credentials, you can proceed to try logging in using remote desktop access. By using a tool like PsExec, it becomes possible to execute commands on the machine remotely. However, troubleshooting username and password issues may arise. In this challenge, attempts with the provided credentials "Bill" and "Bob" do not yield the desired access.

Exploring the Web Server

Moving on from the SMB server, Attention shifts to the web server running on a different port (e.g., Port 80). Analyzing the server's response and identifying the underlying technology (e.g., IIS) can provide valuable clues for further exploration. Interacting with the web server allows you to probe for potential vulnerabilities and find avenues for exploitation.

Leveraging Reversal and Gaining Control

While exploring the SMB shares, the ability to upload files to the network share presents an opportunity to Create and execute a reverse shell. By uploading a file and subsequently running it, you can gain control over the system. Leveraging this technique empowers you to execute commands and maneuver within the compromised environment effectively.

Conclusion

Throughout this penetration testing challenge, you have navigated various hurdles, escalated privileges, and gained control over the targeted machine. By demonstrating your ability to successfully root the machine and retrieve both the user and root flags, you have validated your skills in the field of penetration testing.

Recommendations and Reporting

In addition to successfully completing the challenge, it is crucial to provide a comprehensive report to the client. The report should document the testing approach, vulnerabilities identified, and recommendations for strengthening the system's security. By highlighting weaknesses and suggesting remediation measures, you contribute to enhancing the overall security posture of the organization.

Highlights

• Simulating a black box penetration testing scenario
• Rooting the machine and retrieving flags as proof of compromise
• Exploring SMB shares and leveraging anonymous access
• Troubleshooting username and password issues
• Interacting with the web server for further exploitation
• Uploading and executing files to gain control
• Providing a comprehensive report for the client

FAQ

Q: What is the objective of the penetration testing challenge? A: The objective is to root the machine and find both the user flag and root flag as proof of exploitation.

Q: Is writing a report mandatory for this challenge? A: While it is not compulsory, it is highly encouraged to develop report-writing skills and provide insights to the client.

Q: How can I Interact with the SMB server without any credentials? A: Attempt anonymous access to the shared folders and look for potential information.

Q: Why did the provided username and password combinations not work for remote desktop access? A: There may be issues with the credentials or deliberate misdirection in the challenge.

Q: What steps can be taken after gaining access to the web server? A: Analyze the server's response, identify vulnerabilities, and further exploit the system.

Q: How can I gain control over the system through the SMB shares? A: Upload a file and execute a reverse shell to maneuver within the compromised environment.