Offensive Security Tooling: Shells Overview (TryHackMe)

In this article, I will write a write-up for Shell Overview that covers Shell Overview, Reverse Shell, Bind Shell, Shell Listeners, Shell Payloads, Web Shell, and a Practical Task.

1. What is the command-line interface that allows users to interact with an operating system? Shell

2. What process involves using a compromised system as a launching pad to attack other machines in the network? Pivoting

3. What is a common activity attackers perform after obtaining shell access to escalate their privileges? Privilege Escalation

4. What type of shell allows an attacker to execute commands remotely after the target connects back? Reverse Shell

5. What tool is commonly used to set up a listener for a reverse shell? Netcat

6. What type of shell opens a specific port on the target for incoming connections from the attacker? Bind Shell

7. Listening below which port number requires root access or privileged permissions? 1024

8. Which flexible networking tool allows you to create a socket connection between two data sources? socat

9. Which command-line utility provides readline-style editing and command history for programs that lack it, enhancing the interaction with a shell listener? rlwrap

10. What is the improved version of Netcat distributed with the Nmap project that offers additional features like SSL support for listening to encrypted shells? ncat

11. Which Python module is commonly used for managing shell commands and establishing reverse shell connections in security assessments? subprocess

12. What shell payload method in a common scripting language uses the exec, shell_exec, system, passthru, and popen functions to execute commands remotely through a TCP connection? PHP

13. Which scripting language can use a reverse shell by exporting environment variables and creating a socket connection? Python

14. What vulnerability type allows attackers to upload a malicious script by failing to restrict file types? Unrestricted File Upload

15. What is a malicious script uploaded to a vulnerable web application to gain unauthorized access? Web Shell

    Now that we have learned about the different types of reverse shells, let's test our knowledge with a practical exercise, and let's get the flag in the format THM{} from the vulnerable web server. Click on the Start Machine button to start the challenge. After that, it will be accessible on the following URLs:

    • MACHINE_IP:8080 hosts the landing page

    • MACHINE_IP:8081 hosts the web application that is vulnerable to command injection.

    • MACHINE_IP:8082 hosts the web application that is vulnerable to an unrestricted file upload.

You can access the above using the AttackBox, which will display on a split screen, or you can use your own access through the VPN.

Note: Please allow 2 minutes for the VM to fully boot up.

For the next two questions refer to this YouTube Video for more context or help navigating them.

16. Using a reverse or bind shell, exploit the command injection vulnerability to get a shell. What is the content of the flag saved in the / directory? THM{0f28b3e1b00becf15d01a1151baf10fd713bc625}

17. Using a web shell, exploit the unrestricted file upload vulnerability and get a shell. What is the content of the flag saved in the / directory? THM{202bb14ed12120b31300cfbbbdd35998786b44e5}

Thank you for reading my article. Please leave any questions or comments on improving my learning journey and the THM challenges.