by Protect Uploads on WordPress.org
Protect your uploads directory. Prevent browsing, add watermarks, disable right-click, and password-protect files. For more information, visit protect …

Administration Page for the plugin.
The uploads directory is where the files of the WordPress library are stored. Unfortunelty, this directory is not protected. A person who wants to see all your library could list it instantly going to : http://yourwebsite/wp-content/uploads . This plugin will hide the content by adding an index.php file on the root of your uploads directory or by setting an htaccess which will return a 403 error (Forbidden Access).
New Features in Version 0.6.0:
Available languages: