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.
Comment:
If the user infected with W32.Videoworm, sends the following message before starting the conversation with another buddy in the contacts list, "veja soh do que uma camera escondida eh capaz rsrsrsrs!!!<Clickable URL>
When the buddy clicks this link, downloads video.exe and starts spreading through MSN messenger and starts sending spam mails.