Apache mod_rootme

On a web server, mod_rootme Apache module (https://github.com/sajith/mod-rootme) can be installed for a privileged backdoor. Although Apache is usually not running as root, mod_rootme enables root access by using a pre-fork hook to take advantage of the master Apache process when it still has root permissions.

Once compiled, copy mod_rootme.so to the Apache modules directory (often /usr/lib/apache2/modules) and add the following string to the Apache config file (usually /etc/apache2/apache2.conf or /etc/httpd/conf/httpd.conf):

LoadModule rootme_module /usr/lib/apache2/modules/mod_rootme.so

To use the backdoor, connect to Apache using NetCat and type get root.