access amazon mysql database using mysql database details

our mysql database is hosted on amazon aws, and someone steals our database details via our php connection files and now he has details like dbname, password, dbhost etc. can he take our mysql database backups, or can he delete our mysql tables?

If he can then how can i prevent this. Can you tell me one more thing that how can he access my database using only our database details.

I have already blocked the unauthenticated ip login. So plz help us to prevent our database on amazon.

thanks.