Computer Virus and Top ten destructive virus in the world

Computer Virus

A computer virus is a program, script, and macro which is planned to cause harm; steal private information, modify data, send e-mail and display messages. More importantly, when the virus is executed then it spreads by
copying itself into or over the following:-

• Data files


• Programs


• Boot sector of a computer's


• Hard drive


• Potentially anything else writable.

Virus writers use detail knowledge of security vulnerabilities to gain access to a host's computer.

When was term “Virus” first Used

The theory of a computer program capable of reproducing itself was first mentioned byJohn von Neumann in his 1949 "Theory of self-reproducing automata" essay.

First computer virus ever created.

Elk Cloner was the first computer virus written by Rich Skrenta in 1982. He was a 15-year old high school student at the time. The Elk Cloner virus spread to other computers by monitoring the floppy drive and copying itself to any floppy diskette. Once a floppy was infected it would infect all other computers that used the disk was. A computer that was infected would display a short poem on every 50th boot.

How to protect your computer from a viruses

Anti-virus software is the solution to protect a computer from viruses. Once installed on a computer an antivirus monitors, detects, and cleans any computer viruses.

Examples of computer viruses

There are many types of a computer virus such as:-

• Appending virus


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  Boot sector virus

  
  


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  Space filler virus

  
  


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  Cavity virus

  
  


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  CMOS virus

  
  


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  Companion virus

  
  


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  Encrypted virus

  
  


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  Exe Virus

  
  


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  Rabbit Virus

  
  


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  MBR virus

  
  


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  Non-resident virus

  
  


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  Overwrite virus

  
  


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  Stealth virus

  
  

History of computer viruses is too long and it is very difficult to cover it in a single article. in the following, I am giving the list and short introduction of 10 most destructive viruses in the world ever.

10 Most destructive virus in the world

1. ILOVEYOU

The ILOVEYOU is considered one of the most virulent computer virus ever created. The virus managed to wreck havoc on computer systems all over the world; causing damages totaling in at an estimate of $10 billion. 10% of the world’s Internet-connected computers were believed to have been infected. The virus was created by two Filipino programmers, Reonel Ramones and Onel de Guzman.

2. Code Red

code red was discovered by two eEye Digital Security employees in 2001. The pair were drinking Code Red Mountain Dew at the time of discovery so its name become code red. The worm targeted Microsoft IIS web server installed computer and exploiting a buffer overflow problem in the system. It leaves a very little trace on the hard disk as it is able to run entirely on memory, with a size of 3,569 bytes. Once infected, it will proceed to make a hundred copies of itself but due to a bug in the programming; it will duplicate even more and ends up eating a lot of the resources of the system.

3. Melissa

in 1999 Melissa was created by David L. Smith. It started as an infected Word document that was posted up on the alt-six USENET group, claiming to be a list of passwords for pornographic sites. This got people curious and when it was downloaded and opened, it would trigger the macro inside and unleash its payload. The virus will mail itself to the top 50 people in the user’s email address book and this caused an increase in email traffic and disrupting the email services of governments and corporations. It also sometimes corrupted documents by inserting a Simpsons reference into them.

4. Sasser

 it was created by computer science student Sven Jaschan in 2004. it slows down and crashes the computer while making it hard to reset without cutting the power; the effects were incredibly disruptive, with millions of computers being infected, and important, critical infrastructure affected. The worm took advantage of a buffer overflow Vulnerability in Local Security Authority Subsystem Service (LSASS); which controls the security policy of local accounts causing crashes to the computer. It will also use the system resources to propagate itself to other machines through the Internet and infect others automatically.

5. Zeus

It's a Trojan horse made to infect Windows computers so that it will perform various criminal tasks. The most common of these tasks are usually man-in-the-browser keylogging and form grabbing. The majority of computers were infected either through drive-by downloads or phishing scams. First identified in 2009.

6. Conficker

Also known as Downup or Downadup, Conficker is a worm of unknown authorship for Windows. It was first to appear in 2008 and its name comes from the English word, configure and a German pejorative.It infects computers using flaws in the OS to create a botnet. It's a malware and was able to infect more than 9 millions computers all around the world, affecting governments, businesses, and individuals.

7. Stuxnet

Israeli Defence Force and American Government created, Stuxnet is an example of a virus created for the purpose of cyber warfare, as it was intended to disrupt the nuclear efforts of the Iranians. It was estimated that Stuxnet has managed to ruin one-fifth of Iran’s nuclear centrifuges and that nearly 60% of infections were concentrated in Iran.

8. Mydoom

Mydoom was a worm for Windows appeared in 2004 that became one of the fastest spreading email worms since ILOVEYOU. The author is unknown and it is believed that the creator was paid to create it since it contains the text message, “Andy; I’m just doing my job, nothing personal, sorry,”. It was named by McAfee employee Craig Schmugar, one of the people who had originally discovered it. ‘mydom’ was a line of text in the program’s code (my domain) and sensing this was going to be big, added ‘doom’ into it.The worm spreads itself by appearing as an email transmission error and contains an attachment of itself. Once executed, 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. 

9. CryptoLocker

CryptoLocker a form of Trojan horse targeted at computers running Windows. It uses several methods to spread itself, such as email, and once a computer is infected, it will proceed to encrypt certain files on the hard 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, the files will still remain encrypted. 

10. Flashback

The Trojan was first discovered in 2011 by antivirus company Intego as a fake Flash install. In its newer incarnation, a user simply needs to have Java enabled (which is likely the majority of us). It propagates itself by using compromised websites containing JavaScript code that will download the payload. Once installed, the Mac becomes part of a botnet of other infected Macs.