source: http://www.securityfocus.com/bid/1415/info

Sending a stream of binary zeros to any one of a number of Windows 2000 ports can cause 100% CPU utilization. The ports that were found vulnerable include TCP ports 7, 9, 21, 23, 7778 and UDP ports 53, 67, 68, 135, 137, 500, 1812, 1813, 2535, 3456. 

This can easily be reproduced from a Linux system using netcat with an input of /dev/zero, with a command such as "nc target.host 7 < /dev/zero" for the TCP variant or "nc -u target.host 53 < /dev/zero" for the UDP variant.