MariaDB lost database MYSQL after 1-2 days

Question

I have a big problem and i tried to fix this since weeks. After 1-2 days i lost the database "mysql" in MariaDB (Server version: 10.5.12-MariaDB MariaDB package) running on OpenSuSe Leap 15.3. Only the client database (but without more tables) and the database "information_shema" exists. Database "mysql" not more exists. I need to reinstall the database server, set all the passwords, etc., import the database from a backup and all works fine, but after one day, more ore less, the database "mysql" is not more. Also the folder "/var/lib/mysql" contains only the folder of my clients database and of "information_shema". Only the user "root" have access to the database server and only with password. Every day i run a backup of the databases, but i have now no more idea how this is posible. I changed all passwords for the reason it is not hacked, but always the same result. Have someone an idea? Many thanks in advance for your help!

Answer 1

As others have mentioned, the mysql database doesn't spontaneously disappear from MariaDB. Check for SQL injection in your logs. As best practice however, I recommend you to create a user specifically for the application connecting to the database.

CREATE USER appuser IDENTIFIED BY 'password'

If the application is running on the same machine, you can restrict external access like so:

CREATE USER appuser@localhost;

Then, grant the application user access only to the application database(s).

GRANT ALL ON app_database.* to appuser;

Or if you created the user with the host database:

GRANT ALL ON app_database.* to appuser@localhost;

Worst case scenario now is that an SQL injection will only expose the application database, not the server's user passwords. As always, remember little Bobby tables.