Did you know that any web user can easily know the site is created in Joomla! by typing the URL to access the administration area (i.e. www.site name.com/administration). This makes hackers hack the site easily once they crack id and password for Joomla!.
There is an easy way to secure access to the Administrator section and that is by using the jSecure plugin. jSecure Authentication module prevents access to administration (back end) login page without appropriate access key. It is available for download from www.joomlaserviceprovider.com