Computer virus
(worm)
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From Wikipedia, the free encyclopedia.
A computer worm is a self-replicating computer program, similar to a
computer virus. A virus attaches itself to, and becomes part of, another
executable program; a worm is self-contained and does not need to be part of
another program to propagate itself.
The name 'worm' was taken from The Shockwave Rider, a 1970s science fiction
novel by John Brunner. Researchers writing an early paper on experiments in
distributed computing noted the similarities between their software and the
program described by Brunner and adopted the name.
The first worm to attract wide attention, the Morris worm, was written by
Robert Tappan Morris, Jr. at the MIT Artificial intelligence Laboratory. It was
released on November 2, 1988, and quickly infected a great many computers on the
Internet at the time. It propagated through a number of bugs in BSD Unix and its
derivatives. Morris himself was convicted under the US Computer Crime and Abuse
Act and received 3 years' probation, community service and a fine in excess of
$10,000.
In addition to replication, a worm may be designed to do any number of
things, such as delete files on a host system or send documents via email. More
recent worms may be multi-headed and carry other executables as a payload.
However, even in the absence of such a payload, a worm can wreak havoc just with
the network traffic generated by its reproduction. Mydoom, for example, caused a
noticeable worldwide Internet slowdown at the peak of its spread.
A common payload is for a worm to install a backdoor in the infected
computer, as was done by Sobig and Mydoom. These zombie computers are used by
spam senders for sending junk email or to cloak their website's address.[1]
Spammers are thought to pay for the creation of such worms [2] [3], and worm
writers have been caught selling lists of IP addresses of infected machines.[4]
Others try to blackmail companies with threatened DDOS attacks.[5] The backdoors
can also be exploited by other worms, such as Doomjuice, which spreads using the
backdoor opened by Mydoom.
Whether worms can be useful is a common theoretical question in computer
science and artificial intelligence. The Nachi family of worms, for example,
tried to download then install patches from Microsoft's website to fix various
vulnerabilities in the host system (the same vulnerabilities that they
exploited). This eventually made the systems affected more secure, but generated
considerable network traffic, rebooted the machine in the course of patching it,
and, maybe most importantly, did its work without the explicit consent of the
computer's owner or user. As such, most security experts deprecate worms,
whatever their payload.
This article is licensed
under the GNU Free
Documentation License. It uses material from the
Wikipedia article
"Computer worm".
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