Computer virus definition
Computer virus refers to malicious software created to harm a file or a device. Viruses can spread via email attachments, instant messages, file sharing programs, or by self-replicating.
Types of computer viruses
- Worms. Self-replicating viruses that spread through networks and can damage files and systems.
- Ransomware. A virus that takes over the device, encrypts everything on it, and demands payment to give the data back.
- Adware. While not malicious, adware is an unwanted program that displays ads on your device.
- Spyware. A virus that hides inside a victim’s computer, collecting data, and sending it back to the hacker.
- Trojan. A virus disguised as a legitimate program.
- Macro viruses. These viruses are often attached to documents and activated when the documents are opened.
History of computer viruses
- Creeper system. Created in 1971 by BBN technologies, this virus would make copies of itself until the hard drive was full.
- Brain. The first MS-DOS virus was created in 1986 and would disable the computer from booting.
- CIH. Also known as Chernobyl and Spacefiller, the virus damaged Windows computers by overwriting key system files.
- Melissa. One of the first macro viruses, it was attached to an MS Word document.
- WannaCry. One of the world’s most dangerous and prominent ransomware viruses.