ProCTF - Cybrics Quals 2019

For this challenge, we are provided with the username and the password for a machine. Information

The ssh session gives us a strange shell: Shell

By trying some commands we run into an error message: Prolog

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:


Let’s try: Command

Searching through the directories we find the flag file in the user’s home: Flag

After I solved the challenge, reading the documentation, I found out that running the shell command without parameters would have gave me the default system shell, making it easier to move through the system.