Virus-like program that spreads automatically to other computers by sending itself out by email or by any other means. A program that propagates itself by attacking other machines and copying itself to the affected machine.
Worms have self-replicating code that travels from machine to machine by various means. A worms first objective is merely propagation. Worms can be destructive depending on what payload they have been given. Worms may replace files, but do not insert themselves into files.
IRCbot.06.040 exploits "Windows Server Service Buffer Overflow" MS06-040 against Windows 2000 machines. It creates a service with the display name "Windows Genuine Advantage Registration Service". It opens port 18067 and waits for commands.