When you use Joomla CMS to build your site, it is important that you have your back-end secured; otherwise, it would not be hard for an advance user to intrude into your back-end. So, to make it more secure, what are we gonna do?
I have been using one plugin that basically will help you make your website secure. The name of the plugin is called JSecure. It is not free; however, if you are lucky and patient to surf for the download link on the internet, you can get a shared one. I personally always surf for the free one. However, if you want to save time and want to make it sure, you can spend about $10 for that plugin.
Basically, what this plugin does is just doubling the pass point. By default, when you login to your back-end, you will have to go http://yourdomain.com/administrator. However if you use this plugin, you have to go through http://yourdomain.com/administrator/?XXXX; whereas, XXXX is the letters that you set up. So, only those who know XXXX will get access to the login page. Therefore, this plugin doubles your security.
You can learn more about this plugin HERE.
You can download this JSecure Joomla plugin HERE.