"Though very simple, Sapphire represents a significant milestone in the evolution of computer worms, " said the report.

BBC: Aggressive net bug makes history

This reputation has been mauled in the past few months by computer worms and viruses, such as Sobig.

ECONOMIST: About morals or money? | The

Computer worms are malicious software applications designed to spread through computer networks.

FORBES: Worm Attacks Coming For Google's Android - Kaspersky Lab

However, computer-security companies (which, of course, have a vested interest) warn that even apparently benevolent worms are not all good.

ECONOMIST: Target: Microsoft | The