Use only strong passwords for the database connection. A strong password should include letters in varying case, digits and punctuation marks and contain at least 8 characters. This will reduce the risk of successful password bruteforce.

The database should be accessed using a dedicated account with minimum sufficient access privileges (not "root").

1. Verify that the password follows the security guidelines in "/bitrix/php_interface/dbconn.php" ("$DBPassword" variable).
2. Check the privileges of the database access account.