Computer virus

  1. Meaning of Computer Virus:

A computer virus is a type of malicious software (malware) that is designed to replicate itself and spread from one computer to another. It attaches itself to legitimate programs or files and, when these infected files are executed or opened, the virus code is activated. Computer viruses are intended to cause harm, disrupt normal computer operations, steal information, or carry out other malicious activities without the user’s consent or knowledge.

  1. Examples of Computer Viruses:

There are several examples of computer viruses that have caused significant damage over the years:

  1. -ILOVEYOU: This virus spread through email as an attachment and caused extensive damage by overwriting files and spreading to the victim’s email contacts.
    1. Conficker: Conficker exploited vulnerabilities in Windows operating systems and created a massive botnet, enabling remote control of infected computers.
    2. WannaCry: This ransomware worm encrypted files on infected systems and demanded payment in cryptocurrency for decryption, affecting numerous organizations worldwide.
    3. Melissa: The Melissa virus spread through infected Word documents and significantly overloaded email servers.
    4. Stuxnet: This highly sophisticated virus was designed to target specific industrial control systems, specifically targeting Iran’s nuclear facilities.
  2. Code Red: This virus targeted Microsoft IIS web servers and spread by exploiting a vulnerability in the server software. It defaced websites and caused traffic congestion on the internet.
  3. Nimda: Nimda was a multi-faceted virus that spread through various methods, including email, web browsing, and network shares. It could infect a system in multiple ways, making it difficult to contain.
  4. Sasser: Sasser exploited a vulnerability in Microsoft Windows operating systems and spread through the internet by scanning for vulnerable computers. It caused computers to crash and reboot repeatedly.
  5. Mydoom: Mydoom was one of the fastest-spreading email worms, using social engineering techniques to trick users into opening infected attachments. It also launched DDoS attacks against certain websites.
  6. Slammer (SQL Slammer): This fast-spreading worm targeted Microsoft SQL Server databases and exploited a vulnerability. It caused widespread internet congestion due to its rapid propagation.
  7. Blaster (MSBlast): Blaster exploited a vulnerability in Microsoft Windows and caused infected computers to restart repeatedly. It also attempted to launch a DDoS attack on
  8. CryptoLocker: CryptoLocker was a ransomware virus that encrypted files on infected computers and demanded payment in exchange for the decryption key.
  9. Zeus (Zbot): Zeus was a Trojan virus designed to steal sensitive information, particularly banking credentials, from infected computers. It could also be used to create a botnet.
  10. Storm Worm: This worm spreads through email with enticing subject lines and infected attachments. It was used to create a massive botnet for various malicious purposes.
  11. Gameover Zeus: This evolved from the Zeus Trojan and was primarily used for financial theft and fraud, including banking credential theft and distributing other malware.


  1. Sources of Computer Virus:

Computer viruses can originate from various sources:

  1. Internet: Downloading files or software from untrustworthy websites or peer-to-peer networks can expose you to viruses.
  2. Email Attachments: Opening attachments from unknown or suspicious sources can introduce viruses to your system.
  3. Removable Media: USB drives, external hard drives, and other storage devices can carry viruses if used on infected systems.
  4. Software Downloads: Infected software obtained from unreliable sources can contain hidden viruses.
  5. Malicious Links: Clicking on links in phishing emails or on malicious websites can lead to virus infections.
  6. Networks: Computers connected to the same network can spread viruses if one of them is infected.

Detection and Prevention of Computer Virus:

  1. Antivirus Software: Install reputable antivirus software to detect and remove viruses from your system.
  2. Regular Updates: Keep your operating system, software, and antivirus programs up to date to patch vulnerabilities that viruses might exploit.
  3. Caution with Downloads: Only download software, files, and attachments from trusted sources.
  4. Email Vigilance: Be cautious when opening email attachments or clicking on links, especially from unknown senders.
  5. Firewall: Enable a firewall to monitor and control incoming and outgoing network traffic.
  6. Backup: Regularly back up your important data to an external source to prevent loss in case of a virus attack.
  7. User Education: Educate yourself about common online threats and safe internet practices to avoid falling victim to viruses.

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