The Most Famous (or Infamous) Viruses and Worms of All Time

The first sign of computer worm activity dates back to 1982, when a program called Elk Cloner squirmed through Apple II systems. The SCA virus and Brain, written for IBM PC compatibles and Amigas, would pop up in the late 1980s, followed by the Morris Wor

In 1991, the world waited and watched for the Michelangelo virus, a time bomb that bombed. Set to deploy on March 6 (Michelangelos birthday), the virus was designed to overwrite critical drive sectors, but it did little damage in reality.

Named after a lap dancer in Florida, the 1999 Melissa worm is considered the first destructive mass-mailer targeting Microsoft customers. The worm was programmed to spread via Microsoft Word- and Outlook-based systems, and the infection rate was startling

The 1999 Explorer.zip worm deleted Word, Excel, PowerPoint files and other files.

Still widely considered one of the most costly viruses to enterprises, the 2000 ILOVEYOU worm, also known as VBS/Loveletter or Love Bug, used social engineering and catchy subject lines to trick Windows users into launching the executable. The worm spread

Another poseur, the Anna Kournikova (or VBS.SST@mm) worm, which appeared in February 2001, showed up in Microsoft Outlook inboxes with an attachment that claimed to be a picture of the comely tennis star Anna Kournikova. But when users clicked on the atta

SirCam was a malicious code that spread through e-mail and unprotected network shares. The damage from SirCam was somewhat limited, but what was to follow would set the tone for a spate of network worms that caused billions of dollars in business costs.

In July 2001, Code Red spread via a flaw in Microsofts Internet Information Server. The worm exploited a vulnerability in the indexing software distributed with IIS and caused widespread panic by defacing Web sites with the stock phrase Hacked By

Still reeling from the effects of SirCam and Code Red, Windows users would soon have to deal with Klez, an e-mail-borne virus that exploited a flaw in Microsofts Internet Explorer browser and targeted both Outlook and Outlook Express users. Because Klez

Benjamin, which came onto the scene in 2002, affected users of the Kazaa file-sharing program. Benjamin posed as a media file to machines, but, when downloaded, would set up a folder and stuff it with copies of itself. Worse, the copies themselves posed a

The Sober worm, first detected in October 2003, used a wide range of social engineering tactics to trick e-mail users into activating a malicious attachment.

Magistr targeted Outlook Express users, hooking them with an infected e-mail attachment. The virus sent messages to all the contacts in a users address book, complete with attachments comprising random files and an executable with the Magistr code. Magis

W32.Nimda. was a double-threat, operating as a hybrid between a virus and a worm. Like Code Red, it attempted to take over Microsoft IIS systems by utilizing known security holes in the Web server. However, while Code Red used only one security hole, W32.

Reminiscent of the Code Red worm, Slammer exploited two buffer overflow vulnerabilities in Microsofts SQL Server database, causing major congestion of Internet traffic throughout Asia, Europe and North America. The worm infected about 75,000 hosts in the

As Microsoft struggled to cope with the Slammer fallout, there were two new outbreaks with Sobig and Blaster squirming through millions of unpatched Windows machines. The fast-spreading worms crippled network infrastructure globally and the cleanup and re

In January 2004, the MyDoom worm was spotted. A mass-mailer with a payload targeting the Windows operating system, MyDoom quickly surpassed Sobig as the fastest-spreading e-mail worm ever. In addition to seeding Windows machines to create botnets, MyDoom

In early May, Sasser hit. Exploiting a flaw in the LSASS (Local Security Authority Subsystem Service) component, the Sasser worm squirmed through unpatched Windows 2000 and Windows XP machines. Sasser was particularly dangerous and spread rapidly through

Microsoft is credited with reacting swiftly to contain the Sasser spread. But, as the latest Zotob attacks prove, the time to exploit an unpatched flaw has narrowed significantly since the launch of Windows 95 10 years ago.

This scenario originated in the fall of 2005, when Creative Labs shipped 3,700 Zen MP3 players carrying the Wullik-B virus. This year, consumer heavyweights McDonalds and Apple Computer followed suit. As part of a prize promotion, McDonalds Japan distri

Google came under fire — and rightfully so — in 2006 after it distributed e-mails containing the Kama Sutra worm to users of the Google Video Blog group. Apparently, three posts were made that contained the W32/Kapser.A@mm mass mailing virus — a worm t

The Cryzip trojan used a commercial zip library to store a victims documents inside a password-protected zip file and left step-by-step instructions on how to pay the ransom to retrieve the files.

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