UNIX for Dummies Questions & Answers

I have never seen anyone attempt to attack a unix system via a true virus. And the only true unix virus that I ever saw were written by researchers just to demonstrate that it could be done. Worms and trojan horses are the primary problems. And some folks call these (incorrectly) viruses, especially if they involve machine language payloads.

But note that the rlogin bug only requires that the rlogin executable be present on the system. You don't need to allow the r-cmds protocol on your network. You don't need to be running or even have a rlogind anywhere. You don't even need to have connected your system to a network. If you have a broken rlogind executable on your system, any non-root user can use it to become root.

And code delivered to your system via a trojan horse or worm might try it. And rlogin was just an example anyway. Most of the attacks on unix in the past decade have used buffer overrruns.