Web Culture

6 Computer Viruses That Changed The World

Tim Brookes 30-12-2011

computer virusesYesterday we took a look at some of the most damaging high-profile computer viruses A Brief History Of The 5 Worst Computer Viruses Of All Time The word "virus" and its association with computers was affixed by American computer scientist Frederick Cohen who used it to describe "a program that can 'infect' other programs by modifying them to include a possibly... Read More in history, and today we’ll be exploring some of the more obscure ones instead. The term “virus” wasn’t attached to malware until 1983, but viruses as we know them date back to the early 70’s.


These viruses didn’t necessarily make front page news in the same way as Sasser, MyDoom or the Storm Worm did, but many were the first of their kind. It’s also worth noting that many were non-destructive, with the real aim of creating a self-replicating program rather than causing data loss 5 Ways To Clone & Copy Your Hard Drive Read More .

1971: Creeper

Creeper was written in 1971 by Bob Thomas who worked for BBN [Broken URL Removed], and is widely considered to be the first example of a computer worm. The program was self-replicating in nature and non-destructive to data as its main purpose was to test the effectiveness of such code.

computer viruses

Creeper was technically not a virus due to its rather passive nature. The author commented in response to this article:

“…the creeper application was not exploiting a deficiency of the operating system. The research effort was intended to develop mechanisms for bringing applications to other machines with intention of moving the application to the most efficient computer for its task.”

Creeper did not take advantage of an exploit on the (pictured) DEC PDP-10 TENEX systems it came into contact with, and was eventually stopped with a program called Reaper, which was specifically designed to halt the spread.


1981: Elk Cloner

In 1981 a 15-year old called Rich Skrenta stumbled upon the world’s first boot sector virus 7 Types of Computer Viruses to Watch Out For and What They Do Many types of computer viruses can steal or destroy your data. Here are some of the most common viruses and what they do. Read More , Elk Cloner for the Apple II 5 Sites To Play Old Computer Games Once Again Read More . At the time the Apple II used floppy disks to boot into the OS, which made it particularly vulnerable to attacks.

list of computer viruses

If a user booted into the OS from an infected floppy, the virus would be copied to the computer’s memory. Any further floppy disks that were inserted into the computer once Elk Cloner was in the memory would also become infected. Whilst the code was not malicious, the user would see a poem on every 50th boot.

Skrenta’s virus was not only the first to specifically target the boot sector but also one of the first to spread “in the wild” – i.e. outside of the environment it was originally written.


1986: Brain

Considered by many the first computer virus written for MS-DOS How To Get Old DOS Computer Games To Run On Windows 7 Read More (and thus the IBM PC standard), Brain affected floppy disks, more specifically the boot sector of the DOS File Allocation Table (FAT), by moving the real boot sector elsewhere and marking it as “bad”. A copy of the virus replaced the real boot sector, but hard drives were specifically avoided.

list of computer viruses

The virus can be traced back to two brothers from Lahore, Pakistan – Basit and Amjad Iqbal who included the following message:

Welcome to the Dungeon © 1986 Basit * Amjad (pvt) Ltd. BRAIN COMPUTER SERVICES 730 NIZAM BLOCK ALLAMA IQBAL TOWN LAHORE-PAKISTAN PHONE: 430791,443248,280530. Beware of this VIRUS…. Contact us for vaccination…

The virus was originally written as a copyright safeguard for medical software the pair were working on. They received phone calls from all over the world demanding inoculation, and still trade today as Brain NET, an Internet service provider.


1987: SCA

Another first, SCA was the Commodore Amiga’s inaugural computer virus, written by the “Swiss Cracking Association” or “Mega-Mighty SCA”. The group mostly specialised in removing copy protection from floppies, and thus the SCA virus targetted the boot sector of write-enabled disks.

Every 15th reboot the following message was displayed, warning the user that they were infected:

Something wonderful has happened Your AMIGA is alive !!! and, even better…some of your disks are infected by a VIRUS !!! Another masterpiece of The Mega-Mighty SCA !!

The virus only affected write-enabled floppies but would ruin custom bootblocks, such as those used by games. The SCA virus led the same group to release the first ever Amiga virus scanner in order to remove the infection.

1988: Morris Worm

With its source code preserved on a dusty floppy in the Boston Museum of Science, the Morris worm is one of the most famous outbreaks in history – mostly due to a mistake by its author. The Morris worm was in fact one of the first spread via the Internet, and exploited known vulnerabilities within the UNIX operating system.


computer viruses

The worm was originally not written to be malicious, but instead to try and gather information about the size of the Internet according to its author, Robert Tappan Morris. What made the worm such an issue was its method of spreading, which would re-infect every 1 in 7 PCs that claimed to already be infected.

This proved to be overkill and it is thought that of the 60,000 machines connected to the Internet at the time, 10% were affected. Morris was studying at Cornell University at the time, but chose to release the worm from MIT to avoid detection. He was later the first person to be convicted under the USA’s 1986 Computer Fraud and Misuse Act.


He received three years probation, 400 hours community service and a $10,000 fine. The worm is thought to have caused somewhere between $10 million -$100 million in damage and undoubtedly changed Internet security forever.

2006: Leap

Leap, also known as the Oompa-Loompa virus was the first to ever infect Apple’s cherished OS X operating system. Whilst it was not a full-blown outbreak, and didn’t even transfer via the Internet, Leap proved that no matter how tight security was, there were always going to be potential vulnerabilities Are Antivirus Programs Necessary for Mac? Read More .

The virus transferred itself via iChat’s Bonjour buddy list, but only over local area networks. In order for a machine to become infected the user had to accept the latestpics.tgz archive, open it and run the executable (claiming to be an image of Apple’s next OS) within.

The virus would infect non-system applications owned by the user, but due to a bug within the virus, any infected programs refused to run after exposure to Leap. Removal of the virus did not require a complete OS re-install, and thus Leap will always be considered a low threat virus, albeit a world-changing one.


I hope you’ve enjoyed learning about some of my “favourite” viruses, their origins and of course the knock-on effects. Whilst infections like Elk-Cloner and Creeper weren’t particularly damaging they were highly innovative and certainly provided a taste of things to come.

Do you know of any other interesting virus outbreaks? Remember that sinking feeling once your machine was infected? Have a rant below!

Image Credits: Shutterstock, DEC PDP-10, Apple II, Brain virus

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  1. cleaner for ice maker
    March 12, 2012 at 2:08 am

    An additional 1 bites the dust , or at minimum another web log post stings the dust. Your weblog rocks my article network hold up the terrifying causes.

  2. Dinesh4512
    January 9, 2012 at 8:51 pm

    Worst souvenir was Tchernobyl which did a lot of damage to a friend's (He even had to reflash his motherboard). My first virus infection was 'Khobar' (I believe it came from pakistan). What was truly insane was getting updated virus patterns: intervals were of several months - no live update at the time!! Another famous one was pingpong which actually showed a bouncing ball from time to time :-S

  3. Melawe
    January 9, 2012 at 1:43 pm

    They might be bad but they are fun to remove, well maybe not the stubborn ones. :P

  4. ibsteve2u
    January 9, 2012 at 10:34 am


  5. ComputerPro2000
    January 8, 2012 at 12:05 am

    How could anyone forget a 1980s computer saying, "Your PC is now Stoned!"

  6. Cendecon
    January 4, 2012 at 11:56 pm

    Did anyone mention the I love you virus? SMH

  7. JamieKateSacedo25
    January 1, 2012 at 2:17 pm

    you didnt mention I LOVE YOU virus from the philippines... ;) it was more destructive 

    • Cendecon
      January 5, 2012 at 12:40 am

      Ahh, I just saw this... great minds!

  8. Dan
    December 30, 2011 at 12:53 pm

    How about the ILOVEYOU virus?  It affected more than 50million users worldwide and prompted the Pentagon, CIA, and many other government & large corporations to shut their mailing system.

    • Butterfly
      January 2, 2012 at 2:30 am

      yes i agree...and im so proud it came from the philippines hahaha...the I-LOVE-YOU virus was more destructive than the mentioned malwares above..haha

  9. Zutronic
    December 30, 2011 at 6:01 am

    Ha! I remember all of these and how much media coverage these got.

  10. Ferrarifan1956
    December 30, 2011 at 5:44 am

    I downloaded this for the first time and i am glad i did some how over 300+ Trojan Horses and other types of bad viruses entered my computer and making it go bananas,  but this software tackled the problem and now my computer and i are quite happy. thank  you MALWAREBYTES Anti Malware.This will stop the hackers screwing my computer and stealing my precious photos of Michael Schumacher and research data.