Worst Computer Viruses in History

London, 14th August 2015: Antivirus and mobile security firm, BullGuard, has produced an infographic that highlights the major viruses of the past three decades and just how vulnerable the internet can be to these destructive strings of code.

Viruses can be an irritating menace or they can be devastatingly destructive. It’s hard to believe today that when computing for the masses took off in the 1980s the concept of a computer virus was something generally scoffed at and dismissed as outlandish.

Today, we know different; their potential for harm has mirrored their increasing spread. From Slammer, which caused an estimated $10 billion worth of damage, to Conficker, which caused chaos and panic and infected about 15 million computers, they now spread from one corner of the world to another at the speed of light.

1988 – The Morris Worm
Robert Morris, a university student released a worm which affected 10 percent of all the computers connected the internet.

The virus slowed the computers down to a crawl and brought all the machines used by the Massachusetts Institute of Technology to a halt.

It was the first virus to infect Microsoft Word documents. Morris later became an associate professor at MIT.
1999 – Melissa [1]
Melissa was spread via a file to a Usanet group called alt.sex and the file contained passwords for 80 pornographic websites. It infected millions of machines. The virus was named after a Miami-Based stripper.

As soon as the email receipent opened the file, the worm attempted to mail itself to the first 50 email addresses it could take from the computer. Its creator David L.Smith was banned from even going near a computer without consent from a court.
2000 – I Love You
The “I love you” virus spread when it was downloaded as an email attachment. It then started copying itself several times and hiding in folders on the hard drive.

It did about $10 billion worth of damage, rapidly infecting networks around the world.
2001 – Anna Kournikova [2]
Jan de Wit created a virus that tricked the reciepent into opening message that strongly suggested they would be privy to aglimpise of Russian tennis star Anna Kournikova’s curves.

It became so notorious that it featured in an episode of friends.
2001 – Nimda[3]
Nimda is ADMIN spelled backwards. Within 25 minutes of as release it had become the internet’s most widespread worm.

It infected email and sent itself out to email contacts : broke into web servers and infected files on websites.

It appeared one week after 9/11 leading to speculation that it was created by state actors or even terrorist groups.
2003 – Slammer[4]
It caused about $10 billion worth of damage. Rapidly infecting networks around the world. Slammer caused a denial of service on Internet hosts and dramatically slowed down Internet traffic, infecting most of its 75.000 victims within 10 minutes.

Fifteen minutes after its first attack, the Slammer virus infected nearly half of the servers that hold up the Internet.
2004 – MyDoom[5]
It was spread through an email attachment which usuallly had an innocuous title such as “Mail Delevery System” or “Mail Transcation Failed”.

It was the fastest spreading virus of all time. A Euro 250.000 reward to find its creator – he was never discovered. Its aim was to assault Google, Altavista and Lycos and at its peak it managed to shut down Google for almost a day.

In February 2004, it infected 1 in 12 emails with 100.000 interceptions taking place every hour.
2004 – Sasser[6]
It exploited a vulnerability in Local Security Authority Subsystem Services (LSAS) It’s creator Sven Jaschan released Sasser into the wild on his 18th birthday.

Sasser made it difficult to shut down machines and infected many computers.
2006 – Leap_A
It proved that Apple is not so safe after all. Using the iChat instant messaging programme Leap_A spread across vulnerable Mac computers.

After infecting the computer it searched through iChat and sent each person on the iChat list a message which contained a corrupted file that appeared as a JPEG image.
2007 – Storm Trojan [7]
Through an email attachment it inundated thousands of computers creating a huge global network of computers enslaved. Its peak up to 10 million CPUs infected.

Each computers would then attempt to infect other computers. It was eventually contained by antivirus companies.
2008 – Conflicker [8]
It caused chaos and panic and Microsoft created a high profile industry group yo counter the virus. Appeared in 2008 and infected up to 15 million computers.

Its main effect was to prevent people from installing Windows updates and wntivirus software.

It downloaded additional code that could hijack computers and steal personal information.
2010 – Stuxnet [9]
The first virus to specifically target critical national infrastructure. Caused centrifuges at Iran’s Netanz nuclear enrichment facility to spin out of control and effectively self-destruct. Designed to self-destruct in June 2012. It was inflitrated into Natanz via a USB stick.

Widely believed to have been developed by the Isrealis and Americans to slow down Iran’s nuclear programme.
2013 – Cryptolocker [10]
A particularly nasty piece of malware that made infection personal. Delivered via en email attachment, Cryptolocker would freeze up a user’s personal files including photos and documents and demand a ransom in order to release them.

Its encyrption method was considered unbreakable causing much alarm and an estimated total ransom of $27 million paid in one three months period.

Was eventually halted when its database of encyprtion keys was discovered and posted online. However it spawned a number of clones that are still active today