For this challenge, we are provided with the username and the password for a machine.
The ssh session gives us a strange shell:
By trying some commands we run into an error message:
Searching the error message on Google tells us that it’s probably Prolog. The prolog’s documentation tells us that the syntax to run a system command is:
Searching through the directories we find the flag file in the user’s home:
After I solved the challenge, reading the documentation, I found out that
shell command without parameters would have gave me the default
system shell, making it easier to move through the system.