I have a similar issue in the module ‘SQL Injection Fundamentals.’ When I try to open MySQL in my Pwnbox I get the reponse that MySQL is not a valid command. I ran sudo apt update and sudo apt install mariadb-server-10.3. I try to start MySQL but I get the error “ERROR 2002 (HY000): Can’t connect to local MySQL server through socket ‘/var/run/mysqld/mysqld.sock’ (2)”.
Update - Solved my issue by doing the following:
sudo apt update
sudo apt install mariadb-server-10.3
service mysql start (For password I used the one assigned to me using my personal Pwnbox on the HTB website.)
sudo mysql
How to do this using the default Pwnbox instance in the academy I don’t know, but using it with your own personal Pwnbox instance works no problem.