You can also move the attachments, downloads & templates_c folders outside of the public accessible folder tree on your website. WHMCS allows you to do this. If you do move the folders, then you must tell WHMCS where they have been moved to by adding the following lines to your configuration.php file:
Code:
$templates_compiledir = "/home/whmcs/templates_c/";
$attachments_dir = "/home/whmcs/attachments/";
$downloads_dir = "/home/whmcs/downloads/";