My two cents about this machine
Foothold
After you discover that high port, go check it out and enumerate. With a well known tool we always use on Kali, you can find juicy exploits : Warning → they are incomplete, try to figure out what is missed, or if you are not a dev or don’t know Python so much( advice, you must learn it) find the fixed exploit using Google.
Shell Improvement
If you got a shell, it will be basic and unstable.
Lot of people askin’, i usually do :
python3 -c ‘import pty;pty.spawn(“/bin/bash”)’
export TERM=xterm
Ctrl + Z
stty raw -echo; fg
User
Get that flag, is in front of you
Root
As other said, use Linpeas if you want, btw there is a folder you have to enumerate, there are files inside and one of them has juicy infos.
Root Flag
If you know where you are, you know what to search for on Google. Hacktricks will definitely help you.
Nice box, i had fun indeed so thank to its creator!
Hope it helps feel free to DM me if you are stucked 