by this video you will learn how to do reconnaissance with basics. and a way to get reverse shell by bypassing file upload function using burp then a way to Linux privilege Escalation using the SUID.
tryhackme walkthrough - rootme.
here are some useful commands :
https://pastebin.com/raw/wSqmBuUU
to find user.txt flag
to get python bin bash shell
to find SUID permission files
to exploit the suid (https://gtfobins.github.io/)