Here is a tutorial on how to connect to GeoNetwork's MckoiDB through the Druid Database Manager: http://geonetwork-opensource.org/documentation/how-to/druid_dbms

Note that the GeoNetwork 2.4.2 installer will not prompt you to provide a MckoiDB user name and password. Those are generated automatically and stored in

\geonetwork\web\geonetwork\WEB-INF\db\account.prop