No 8. The CIH virus

Unleashed from Taiwan in June of 1998, the CIH virus would overwrite data on the host PC’s hard drive making it no longer workable. It would also overwrite the BIOS of the host, preventing boot-up. It is also known as Chernobyl or Spacefiller and was written by Chen Ing Hau. The virus was responsible for losses of $20 to $80 million worldwide apart from countless amounts of PC data destroyed.

No 7. SQL Slammer

This particular virus was targeted at servers and was pretty successful too at that. It shut down South Korea’s online capacity for 12 hours and affected 500,000 servers worldwide. It would generate random IP addresses and send itself to those IP addresses. If the IP address was a computer running an unpatched copy of Microsoft’s SQL Server Desktop Engine, that computer would begin sending the virus off to other random IP addresses. Slammer infected over 75,000 computers in a period of mere 10 minutes. It generated huge amounts of traffic that disabled network routers by overloading. It cost somewhere around $750 Million in damages.