Your server, your responsibility

You are the admin now

In the Privilege Escalation course you played the attacker, turning small mistakes into root. Here you switch sides: you are the administrator of this server, and your job is to find those mistakes first and shut them down. This is called hardening.

You are logged in as student, and this time you have sudo — the authority to make changes as root. Confirm it:

id
sudo whoami

In the terminal (sudo whoami prints 'root' — you can act as root on this box)

student@vulntech:~$ id
uid=1000(student) gid=1000(student) groups=1000(student),27(sudo)
student@vulntech:~$ sudo whoami
[sudo] password for student:
root

Every weakness you will fix is one an attacker would have used. Knowing the attack is what makes the fix obvious — that is why offence and defence are taught together.

Tip: The golden rule of hardening is least privilege: every user, file and program should have the minimum access it needs to do its job, and no more.