From holding your files ransom to grounding military aircraft, we count 15 of the worst
and most damaging computer viruses in history. Number 15
In September 2013 Dell SecureWorks first observed a ransomware Trojan infecting Microsoft Windows.
CryptoLocker spread via email attachments and an existing botnet. After encrypting files
on the infected PCs, the virus would then display a message that offered to decrypt
the data for a payment in either Bitcoin or pre-paid cash voucher. Operation Tovar, an
international collaboration, managed to isolate CryptoLocker in May 2014. Never the less,
the creators were believed to have extorted around $3 million.
Number 14 In 2001 a Dutch programmer created a worm
virus, which tricked recipients into opening a message that strongly suggested they would
get a personal glimpse of Anna Kournikova. The tempted recipients would then trigger
a malicious program that plundered their Outlook address book. The virus would then forward
itself to every address it found. The flood of emails it unleashed paralysed servers all
over the world. It became so notorious it even featured in an episode of Friends.
Number 13 Created by a 17 year old boy named Sven Jaschan
and released on his 18th Birthday, Sasser and Netsky were first discovered in 2004.
Sasser attacked through a Microsoft Windows security weakness making it difficult to use
and shutdown a PC, while Netsky went through emails with spoofs, causing DoS attacks through
huge volumes of traffic. Sven later claimed to have written the Netsky worms in order
to remove infection of the MYDOOM virus from victims computers. On July 8 2005, he received
a 21 month suspended sentence. He later received 3 years probation and 30 hours community service
in a retirement home. Number 12
Appearing first in October 2001, the Klez virus spread through emails. There were a
number of variants that plagued the internet for several months, some acting as worms and
some as trojans. It could disable anti-virus software and then pose as a virus-removal
tool. As it spread some hackers adapted it to be more effective. It ransacked address
books and could be programmed to spam recipients with multiple emails.
Number 11 In 2008 a super virus appeared. Conflicker
infected millions of computers worldwide including government, business and home PC's in over
200 countries, making it one of the largest known computer viruses in history. With the
ability to crack admin passwords and copy itself to USB drives, it caused considerable
panic, as it infected many high security networks including the French Navy, forcing aircraft
to be grounded. The UK Ministry of Defence reported it had spread onto NavyStar desktops,
aboard Royal Navy warships and submarines. Number 10
CIH, also known as Chernobyl, first appeared in 1998. It is one of the most damaging viruses,
overwriting information and in most cases overwriting the system BIOS. The virus was
spread via an infected firmware update to Yamaha CD drives and a demo version of the
Activision game SiN. Causing damages in the region of $1 billion, the virus is still around
although it only infects Windows 95, 98 and ME.
Number 9 Just one week after the events of 9/11, a
new virus emerged. Nimda (admin spelt backwards) was the fastest replicating attack of its
time. Becoming the internet's most widely spread worm within just 25 minutes of its
release. It slowed down entire networks, causing many systems to crash entirely. Due to the
timing of it discovery, it has been speculated that it was created by a government or terrorist
organisation. Number 8
In general most MAC users feel relatively relaxed about the safety of their machines.
Because Apple produce both hardware and software, the systems are far more closed than PCs.
However in 2006 hackers got in through the iChat instant messaging program, with a corrupted
file that looked like an innocent JPEG. As MACs become more common place, expect more
attacks on their integrity. Number 7
Surfacing in 2007, Storm Trojan infected thousands of computers. Users would be lured into opening
emails with subjects such as '230 dead as storm batters Europe' and 'Naked teens attack
home director'. Once the attachment was opened the Trojan implanted a service that passed
data to other infected computers, each becoming a zombie in a botnet, a huge global network
of computers enslaved by Storm Trojan. Each computer attempting to infect others with
the aim to control the processing power of every single PC on the planet. It was eventually
contained but only after millions of man hours trying to halt its activity.
Number 6 Created by David L Smith who named it after
a Miami based stripper, Melissa was ironically not designed to create harm. However it spread
so quickly that it overloaded servers. Melissa was spread via a file that contained passwords
for 80 pornographic websites to a Usenet group called alt.sex. As soon as the email recipient
opened the file it would attempt to email itself to the first 50 email addresses it
could take from the computer. The FBI reported it as 'wreaking havoc on government and private
sector networks'. Smith was fined $5,000 and served 20 months in jail.
Number 5 In 2003 SQL Slammer, also known as Sapphire
hit the net. Doubling its infections every few seconds, the Slammer virus infected nearly
half the internet servers in just 15 minutes. Its main targets were companies running SQL
servers. Amongst many other high profile victims, it managed to bring down the Bank of America's
ATM system, disrupted part of Seattle's emergency services and caused Continental Airlines to
cancel several flights. Causing damages in the region of $1.2 Billion and infecting 200,000 PC's.
Number 4
In the summer of 2001 two employees at eEye Digital Security discovered a new virus. While
drinking Code Red Mountain Dew at the time, they decided to call this new virus, Code
Red. The virus defaced many websites with the message 'Hacked By Chinese'. Causing damages
of $2.6 Billion and infecting over 1 Million PCs, this virus would launch DDOS attacks
on several fixed IP addresses. The highest profile victim being the White House.
Number 3 If you received an email labelled 'I LOVE
YOU', would you open it? Well, over 500,000 people did. In the year 2000 this virus surfaced
just after Melissa hit computers world-wide. It was a standalone programme sent via email
with the title I LOVE YOU. The virus would email itself to the first 50 contacts in the
users address book and embed itself deep into the computer copying itself many times. It
would then download a file that stole passwords and secretly emailed the information to hackers.
Causing damages of $15 Billion doesn't seem very loving.
Number 2 The SOBIG virus is considered one of the most
destructive worms of its time. With many variants, none were more destructive than SOBIG.F. With
damages in the region of $37.1 Billion. This worm appeared only a little more two weeks
before Slammer and infected over 2 Million PCs world-wide. Sending itself in emails from
'big@boss.com' SOBIG.F spread faster than any other email worm prior. Even with a bug
in its code preventing local network infection, it managed to bring freight and computer traffic
to a halt in Washington DC and grounded many of Air Canada's flights.
Number 1 The aptly named MYDOOM was the fastest spreading
virus of all time and in February 2004 it was estimated to be infecting 1 in 12 emails
with 100,000 interceptions taking place every hour. It spread through email and peer-to-peer
networks enabling it to dig deep into the web. It manifested through an email attachment
with titles such as 'Mail Delivery System' or 'Mail Transaction Failed'. Naturally many
people opened the attachment. Its aim was to assault Google, AltaVista and Lycos and
at its peak managed to shut down Google for almost an entire day. Infecting over 2 Million
PCs and causing damages of around $38 Billion. They never found the creator.
So with thousands of new computer viruses being discovered every day, many people wonder
'Who is creating them?' While others simply wonder 'Who is making money from them?'
As always thanks for watching.