Stop hackers from executing scripts if they somehow manage to place them in the uploads directory.
Just put an .htaccess file in the uploads directory with the following contents:
# BEGIN code execution protection
php_flag engine 0AddHandler cgi-script .php .phtml .php3 .pl .py .jsp .asp .htm .shtml .sh .cgi Options -ExecCGI # END code execution protection
Or append it to an already-existing .htaccess, but be warned it may interfere with preexisting rules, so be sure you know what you’re doing.