H2 - Java SQL database

Official page: https://www.h2database.com/html/main.html

Tricks

You can indicate a non-existent name a of database in order to create a new database without valid credentials (unauthenticated):

Or if you know that for example a mysql is running and you know the database name and the credentials for that database, you can just access it:

Tricks from box Hawk of HTB.