This challenge tells us that there’s a setuid binary in our home directory, and that we need to use it read the password from /etc/bandit_pass/bandit20. We’re instructed to execute it in order to figure out how to use the utility. Trying to run it tells us that executes a command as another user, which makes sense. It gives the following usage: Example: ./bandit20-do id. I was confused as to what exactly “id” referred to. Was it the user ID I wanted to execute the command as? Was it the actual numerical ID? After fiddling around for a bit, the answer was apparently much more straight forward.
bandit19@bandit:~$ ./bandit20-do cat /etc/bandit_pass/bandit20
XXXXXXXXXXXXXXXXXXXX
bandit19@bandit:~$