Recommend better permissions

664 is not so great.

The "66" will allow the web server (or whoever owns the files) to write those files. The "4" is much worse as it allows anyone to read that configuration file which contains the database username and password.

Dangerous stuffs!

0440 should only allow the owner of the file (which must be the user php is running under) to read the file, and the zero should keep those passwords safe.