computer security

The Most Dangerous Computer Viruses in History

Getting a virus has actually happened to lots of users in some fashion or another. To most, it is merely a mild hassle, needing a clean-up and then installing that anti-virus program that you’ve been suggesting to set up however never ever navigated to.

However in other cases, it can be a complete disaster, with your computer system becoming a very pricey brick which no quantity of antivirus can safeguard.

The Most Damaging Computer Viruses

computer securityIn this list, we will highlight a few of the worst and notorious trojan horse that have caused a lot of damage in real life. And given that people usually equate general malware like worms and trojan horses as infections, we’re including them too.

These malware have caused significant damage, totaling up to billions of dollars and interrupting vital real life infrastructure. Here are the 9 most famous.


CryptoLocker is a kind of Trojan horse ransomware targeted at computers running Windows. It uses several techniques to spread itself, such as email, and as soon as a computer is infected, it will continue to secure certain files on the hard disk drive and any mounted storage connected to it with RSA public key cryptography. While it is easy enough to remove the malware from the computer system, the files will still remain encrypted. The only way to unlock the files is to pay a ransom by a due date. If the due date is not fulfilled, the ransom will increase considerably or the decryption secrets deleted. The ransom normally amount to $400 in prepaid money or bitcoin.

The ransom operation was ultimately stopped when police and security business managed to take control part of the botnet running CryptoLocker. Evgeniy Bogachev, the ring leader, was charged and the encryption keys were launched to the impacted computer systems. From data gathered from the raid, the number of infections is estimated to be 500,000, with the number of those who paid the ransom to be at 1.3%, totaling up to $3 million.


The ILOVEYOU infection is thought about one of the most virulent virus ever developed and it’s not hard to see why. The virus managed to trash havoc on computer system systems all over the world, causing damages totaling in at a quote of $10 billion. 10% of the world’s Internet-connected computers were thought to have been infected. It was so bad that governments and large corporations took their mailing system offline to avoid infection.

The virus was produced by two Filipino programers, Reonel Ramones and Onel de Guzman. What it did was use social engineering to obtain people to click on the attachment; in this case, a love confession. The attachment was really a script that poses as a TXT file, due to Windows at the time concealing the real extension of the file. When clicked, it will send itself to everybody in the user’s newsletter and proceed to overwrite files with itself, making the computer system unbootable. The two were never charged, as there were no laws about malware. This resulted in the enactment of the E-Commerce Law to attend to the problem.

Code Red

Code Red first appeared on 2001 and was found by two eEye Digital Security staff members. It was called Code Red since the pair were consuming Code Red Mountain Dew at the time of discovery. The worm targeted computers with Microsoft IIS web server set up, exploiting a buffer overflow problem in the system. It leaves little trace on the hard drive as it has the ability to run entirely on memory, with a size of 3,569 bytes. Once infected, it will continue to make a hundred copies of itself but due to a bug in the programming, it will replicate even more and winds up eating a great deal of the systems resources.

It will then introduce a rejection of service attack on several IP address, popular among them the site of the White House. It also permits backdoor access to the server, permitting remote access to the machine. The most remarkable symptom is the message it leaves behind on impacted websites, “Hacked By Chinese!”, which has actually become a meme itself. A patch was later launched and it was quote that it caused $2 billion in lost productivity. An overall of 1-2 million servers were affected, which is remarkable when you think about there were 6 million IIS servers at the time.


It was developed by David L. Smith in 1999. It started as an infected Word file. This got individuals curious when it was downloaded and opened, it would set off the macro inside and unleash its payload. The virus will mail itself to the top 50 people in the user’s e-mail address book and this caused an increase of e-mail traffic, disrupting the e-mail services of federal governments and corporations. It also often damaged documents by placing a Simpsons referral into them.

Smith was ultimately captured when they traced the Word file to him. The file was submitted using a stolen AOL account and with their help, law enforcement was able to apprehend him less than a week since the break out began. He cooperated with the FBI in capturing other infection creators, well-known among them the creator of the Anna Kournikova infection. For his cooperation, he served just 20 months and paid a fine of $5000 of his 10 year sentence. The virus apparently caused $80 million in damages.


A Windows worm first found in 2004, it was developed by computer technology student Sven Jaschan, who likewise developed the Netsky worm. While the payload itself may be seen as just frustrating (it slows down and crashes the computer, while making it hard to reset without cutting the power), the impacts were exceptionally disruptive, with millions of computer systems being infected, and important, crucial facilities affected. The worm made the most of a buffer overflow vulnerability in Local Security Authority Subsystem Service (LSASS), which manages the security policy of local accounts triggering crashes to the computer. It will likewise use the system resources to propagate itself to other machines through the Internet and infect others automatically.

The impacts of the virus were extensive as while the exploit was already patched, numerous computer systems haven’t upgraded. This led to more than a million infections, getting vital infrastructures, such as airline companies, news agencies, public transportation, hospitals, public transportation, etc. In general, the damage was estimated to have cost $18 billion. Jaschen was tried as a minor and received a 21 month suspended sentence.


Though not as damaging as the remainder of the malware on this list, this is one of the few Mac malware to have gain notoriety as it showed that Macs are not immune. The Trojan was first discovered in 2011 by antivirus business Intego as a phony Flash set up. In its more recent version, a user simply has to have Java allowed (which is likely the majority of us). It propagates itself using jeopardized websites containing JavaScript code that will download the payload. As soon as installed, the Mac becomes part of a botnet of other infected Macs.

The bright side is that if it is infected, it is merely localized to that particular user’s account. The problem is that more than 600,000 Macs were infected, including 274 Macs in the Cupertino area, the headquarters of Apple. It is still out in the wild, with a price quote of 22,000 Macs still infected as of 2014.


Likewise referred to as Downup or Downadup, Conficker is a worm of unknown authorship for Windows that made its first look in 2008. The name comes form the English word, configure and a German pejorative.It contaminates computer systems using flaws in the OS to develop a botnet. The malware was able to infect more than 9 millions computer systems all around the world, impacting governments, organisations and people. It was one of the largest known worm infections to ever surface triggering an estimate damage of $9 billion.

The worm works by making use of a network service vulnerability that was present and unpatched in Windows. As soon as infected, the worm will then reset account lockout policies, obstruct access to Windows upgrade and anti-viruses sites, shut off certain services and lock out user accounts among many. Then, it proceeds to set up software application that will turn the computer system into a botnet slave and scareware to fraud money off the user. Microsoft later on provided a repair and spot with many antivirus suppliers supplying updates to their meanings.


Thought to have been created by the Israeli Defence Force together with the American Government, Stuxnet is an example of an infection developed for the purpose of cyberwarfare, as it was meant to interfere with the nuclear efforts of the Iranians. It was estimated that Stuxnet has handled to mess up one 5th of Iran’s nuclear centrifuges and that nearly 60% of infections were focused in Iran.

The computer worm was developed to attack commercial Programmable Logic Controllers (PLC), which permits automation of processes in machinery. It specifically aimed at those created by Siemens and was spread through infected USB drives. If the infected computer system didn’t include Siemens software, it would lay dormant and infect others in a limited style as to not give itself away. If the software exists, it will then proceed to change the speed of the machinery, triggering it to tear apart. Siemens eventually discovered a way to eliminate the malware from their software.


Emerging in 2004, Mydoom was a worm for Windows that turned into one of the fastest spreading e-mail worm given that ILOVEYOU. The author is unidentified and it is believed that the creator was paid to develop it considering that it contains the text message, “andy; I’m simply doing my job, absolutely nothing personal, sorry,”. It was called by McAfee staff member Craig Schmugar, among individuals who had initially found it. ‘mydom’ was a line of text in the program’s code (my domain) and sensing this was going to huge, included ‘doom’ into it.

The worm spreads itself by looking like an e-mail transmission error and contains an accessory of itself. When carried out, it will send itself to email addresses that are in a user’s address book and copies itself to any P2P program’s folder to propagate itself through that network. The payload itself is twofold: first it opens up a backdoor to enable remote gain access to and 2nd it releases a rejection of service attack on the controversial SCO Group. It was believed that the worm was developed to disrupt SCO due to conflict over ownership of some Linux code. It caused a quote of $38.5 billion in damages and the worm is still active in some form today.


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