Most Famous Computer Viruses Ever

They are a nemesis. They dangerous. They cause havoc. They destroy data and make you lose your hard earned money. They make computers sick. They are the virtual diseases.

Computer viruses have been around since long time. As the time progressed, viruses became more and more sophisticated, harder to stop and more destructive. The damage caused by these self-replicating programs is such that a parallel industry of anti-virus makers has come of ages now. Cyber security companies are making billions of dollar just because viruses are out there to give them business. Virus creators argue that they are forcing software makers to give more attention to security aspect. Here we look at the list of some of the most famous viruses of all time.


It is a computer worm that was first released on 18th September 2001. Nimda became the fastest spreading worm ever. Within just 22 minutes, it became the most widespread internet worm. Nimda attacked the Admin accounts (the name “nimda” is reverse of the word “admin”). Both client and server operating systems were infected by this worm. It made use of multiple infection modes, including: email, network shares, compromised websites, IIS vulnerabilities and back doors left open by Code Red virus.

Code Red

This computer worm was first released on 13th July 2001 and by 19th July 2001 it had infected more than 359,000 computers. Code Red defaced websites and displayed a phrase “HELLO! Welcome to http:// www . worm . com! Hacked By Chinese!” Code Red was followed by Code Red II –a similar computer worm released on 4th August 2001.

List of the Most Famous and Dangerous Computer Viruses and Worms.
List of the Most Famous and Dangerous Computer Viruses and Worms.

Mydoom infected Microsoft Windows and it first surfaced on 26 January 2004. It is also known as [email protected], Novarg, Mimail.R and Shimgapi. Mydoom did so much damage that SCO Group offered a reward of $250,000 for the information leading to the arrest of Mydoom creator. Microsoft offered the same amount for the writer of Mydoom.B worm –a variant of Mydoom. On 26th July, the worm attacked Google and completely stopped Google search engine for a major portion of the day. Google stopped! Can you imagine!


Melissa is a mass-mailer MS Word macro virus. It first surfaced on 26th March 1999. Melissa exploited a vulnerability in Microsoft Outlook. This virus was created by David L. Smith; who was arrested and tried. The court sentenced him to 20 months prison term and $5000 fine. Melissa would send emails with infected attachments to the contacts taken from victim’s Outlook contact list.


This virus exploited a buffer overflow vulnerability and made infected system restart or crash. It spreads by using TCP network port 445. Sasser was first noticed on 30th April 2004 and was written by a German student of computer science named Sven Jaschan. Microsoft had announced a prize of $250,000 to anyone who would give information about Sasser creater. Jaschan released the worm on his 18th birthday on 29th April 2004. However, he was tried as a minor and received a 21 month suspended jail term.


This is also known as Lovsan or Lovesan. It began to spread on 11th August 2003 and on 29th August 2003 Jeffery Lee Parson was arrested for writing a variant of Blaster worm. This worm will issue a shutdown warning to the user.


Also known as Love Letter, this computer worm was first sighted on 5th May 2000 in Philippines. It would send email to the target with a subject line as ILOVEYOU and an attachment “LOVE-LETTER-FOR-YOU.txt” … This worm caused a damage of worth $5.5 billion worldwide and infected tens of millions of computers.

Morris Internet Worm

Morris is considered to be the first worm to spread via Internet. It began spreading on 2nd November 1988. It infected around 6,000 UNIX machines and caused a damage worth $100,000 to $10,000,000. Morris was written by Robert Tappan Morris; a student at Cornell University. The worm was launched from MIT.

SQL Slammer

Released on 25th January 2003, SQL Slammer worm is also known as Sapphire worm and Helkern. Within 10 minutes it infected over 75,000 computers running Microsoft SQL Server. It exploited a buffer overrun bug in this database server from Microsoft. A patch was already available to remove this bug –but in a lot of computers the patch had not been applied and it were these machines that became victims of SQL Slammer.

Elk Clonner

This is considered to be the first microcomputer virus. Elk Clonner came alive in 1982 and it was written by a high-school student Rich Skrenta. This virus infected the boot sector of Apple II operating system. On every 50th boot of the machine –the virus would display the following poem:

Elk Cloner: The program with a personality
It will get on all your disks
It will infiltrate your chips
Yes, it’s Cloner!
It will stick to you like glue
It will modify RAM too
Send in the Cloner!


Written by Bob Thomas in 1971, this is considered to be the first self-replicating program -i.e. a virus.

So, ladies and gentlemen, these were the most infamous computer viruses. These programs made life miserable for hundreds of thousands of people. The virus menace is far from over. With new media like Facebook and Twitter are popular nowadays, the trouble-makers now training their guns on these platforms as well. Facebook has been facing several such threats.

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