picoCTF General Skills Guide

Super SSH

Description: Using a Secure Shell (SSH) is going to be pretty important. Can you ssh as ctf-player to titan.picoctf.net at port 55859 to get the flag? You'll also need the password f3b61b38. If asked, accept the fingerprint with yes. If your device doesn't have a shell, you can use: https://webshell.picoctf.org If you're not sure what a shell is, check out our Primer: https://primer.picoctf.com/#_the_shell
Author: Jeffery John
Tags: Easy, General Skills, picoCTF 2024, shell, browser_webshell_solvable, ls
Hints: 1. https://linux.die.net/man/1/ssh 2. You can try logging in 'as' someone with <user>@titan.picoctf.net 3. How could you specify the port? 4. Remember, passwords are hidden when typed into the shell

Theory

According to the description, to get the flag we have to use SSH to get the flag. Well, this is the easiest one I've seen so far, just using SSH and that's it? Well I don't want to explain it again, because we've used it so many times before in OverTheWire games, but to just say it quickly, it's basically connecting to a server's shell, although to specify what part of the server to connect to you put a user and a port like this full command:

ssh ctf-player@titan.picoctf.net -p 55859

Solution

So now we just enter with the SSH command and input the password, and that would be it (I think):

shukularuni-picoctf@webshell:~$ ssh ctf-player@titan.picoctf.net -p 55859 
The authenticity of host '[titan.picoctf.net]:55859 ([3.139.174.234]:55859)' can't be established.
ED25519 key fingerprint is SHA256:4S9EbTSSRZm32I+cdM5TyzthpBryv5kudRP9PIKT7XQ.
This host key is known by the following other names/addresses:
    ~/.ssh/known_hosts:6: [hashed name]
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '[titan.picoctf.net]:55859' (ED25519) to the list of known hosts.
ctf-player@titan.picoctf.net's password: f3b61b38
Welcome ctf-player, here's your flag: picoCTF{s3cur3_c0nn3ct10n_3e293eea}
Connection to titan.picoctf.net closed.

If the "Are you sure you want to continue connecting?" message appears, just input "yes" to continue.

The SSH closes after that, and there we go! That's the flag.