Internet worms: a guide

An internet worm, as defined in the Webopedia of IT terminology, is a program or algorithm that replicates itself over a computer network and invariably performs malicious actions such as shutting a machine down or using up its resources. No network of computers is impenetrable or immune to attacks of this kind, as is shown in the cases below. The Morris worm Created by US university student Robert Morris, this entered the history books as one of the world's first internet worms. Affecting approximately 10% of the world's estimated 60,000 internet-connected computers in November 1988, it was written with the harmless aim of gauging the size of the internet. However Morris, aged 23, made the program too aggressive, and it swamped the nascent network. He was convicted of violating the 1986 Computer Fraud and Abuse Act; the economic damage caused was estimated by a Harvard spokesman to be between $100,000 and $10,000,000. The ILOVEYOU worm This malicious internet worm, written by a student in the Philippines, hit tens of millions of Windows computer users in May 2000. It arrived as an attachment to an email headed simply ILOVEYOU which came from a contact of the recipient. Once opened, the worm automatically sent itself on to everyone in the user's electronic address book, and altered settings on the machine. Parliament shut down its email to prevent damage from the propositional worm; it left approximately £4bn worth of damage in its wake worldwide. The Code Red worm Credited with being the first worm aimed directly at government computers running Windows, Code Red threatened to bring down US state websites in July 2001. The FBI was prompted to issue a rare warning about the computer threat over fears it could bring the internet to a grinding halt. That never materialised, but the threat posed by the worm was keenly felt, largely because its attacks were time-dependent, launching different actions throughout the month. The Conficker worm In March 2009 the House of Commons and the French Navy were among the owners of an estimated 10m Windows computers worldwide infected by a worm known as "Conficker". For a time, experts predicted it could deliver a devastating attack on the internet, timed to coincide with April Fool's Day, and Microsoft offered a bounty of $250,000 (£176,000) for the identification of its creator. The threat of Conficker has not entirely subsided; Greater Manchester Police was temporarily cut off from the national crime database in January this year after finding the bug in its system. The Twitter worm Reckoned to have affected up to 100,000 Twitter accounts, this attack on Twitter took hold while many of the company's US-based security team slept. Although users of third-party applications were unaffected by the hack, thought to be the brainchild of Japanese developer Masato Kinugawa, Twitter users flooded the site with panicked messages until the problem was solved. Kinugawa said he reported the vulnerability to Twitter last month before discovering that the redesigned site – launched on 14 September – had the same problem.