bandit19@bandit:~$ ls -altr
total 28
-rw-r--r--  1 root     root     3771 Sep  1  2015 .bashrc
-rw-r--r--  1 root     root      220 Sep  1  2015 .bash_logout
-rw-r--r--  1 root     root      655 Jun 24  2016 .profile
drwxr-xr-x 29 root     root     4096 Dec 28 14:34 ..
-rwsr-x---  1 bandit20 bandit19 7408 Dec 28 14:34 bandit20-do
drwxr-xr-x  2 root     root     4096 Dec 28 14:34 .
bandit19@bandit:~$ bandit20-do
bandit20-do: command not found
bandit19@bandit:~$ ./bandit20-do
Run a command as another user.
  Example: ./bandit20-do id
bandit19@bandit:~$ ./bandit20-do cat /etc/bandit_pass/bandit20
GbKksEFF4yrVs6il55v6gwY5aVje5f0j
bandit19@bandit:~$