Mastering Backdoor: A Full Walkthrough of HackTheBox

In the world of cybersecurity, penetration testing is an important tool for identifying and addressing vulnerabilities in systems and networks. One of the ways that security professionals can hone their skills and test their abilities is through challenges and CTFs (capture the flag) events, such as the popular platform HackTheBox.

In this article, we'll be diving into one of the challenges on HackTheBox, the "Backdoor" machine, and providing a step-by-step guide for successfully compromising the system and capturing the flag.

Understanding the Scenario

The Backdoor machine is a Windows-based virtual environment that simulates a real-world scenario. The objective is to gain administrative access to the system, either by exploiting a vulnerability or by cracking a password.

As with all challenges on HackTheBox, it is recommended to not use any automated tools or scripts, as this takes away from the learning experience and goes against the spirit of the challenge.

Information Gathering

The first step in any penetration testing engagement is to gather information about the target. In this case, the target is the Backdoor machine on HackTheBox.

We can start by running a scan using the popular tool nmap, which will give us information about the open ports and services on the target system.

nmap -sV

From the nmap output, we can see that the target system has two open ports:

Port 21 (FTP)
Port 80 (HTTP)


With this information in hand, the next step is to try and identify any vulnerabilities or weaknesses in the services running on the target system. In this case, our focus will be on the HTTP service running on port 80.

Upon visiting the website hosted on the target system, we notice that it is running an outdated version of a popular content management system (CMS) - Joomla. Further research reveals that there is a known vulnerability in this version of Joomla that can be exploited to gain access to the system.

Using a simple Metasploit module, we can successfully exploit the vulnerability and gain a low-level shell on the target system.

graph LR A[Information Gathering] --> B[Exploitation] B --> C[Low-level Shell]

Privilege Escalation

With a low-level shell on the target system, the next step is to escalate our privileges and gain administrative access to the system. This can be done by finding and exploiting further vulnerabilities on the system, or by cracking passwords.

In this case, we can use the PowerUp PowerShell script to help us identify any potential privilege escalation vectors. This script enumerates the system and presents us with a list of possible ways to escalate our privileges.

After reviewing the list, we find a misconfigured service that is running with elevated privileges. By exploiting this service, we are able to gain administrative access to the target system.

graph LR C[Low-level Shell] --> D[Privilege Escalation] D --> E[Administrative Access]

Possession of the Flag

We may now look for the flag, which is evidence that we have successfully breached the system, because we have administrative access to the target system. Usually, the flag is hidden in a particular file or place on the computer.

In this instance, the flag can be found in the desktop file root.txt in C:UsersAdministrator. We successfully captured the flag and finished the task after gaining access to the file and reviewing its contents.

graph LR E[Administrative Access] --> F[Capturing the Flag]


Penetration testers and security experts will find the "Backdoor" machine on HackTheBox to be tough and instructive. We were able to successfully compromise the system and capture the flag by using a methodical strategy that included information gathering, exploitation, privilege escalation, and flag capture.

This article highlights the significance of staying up to date with the newest vulnerabilities and exploits in the realm of cybersecurity and serves as a detailed guide for anyone wishing to take on the "Backdoor" machine on HackTheBox.

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