Morris (a.k.a. Internet Worm) - November 1988
This computer virus infected over 6,000 computer systems in the United States, including the famous NASA research Institute, which for some time remained completely paralyzed. Due to erratic code, the worm managed to send millions of copies of itself to different network computers, being able to entirely paralyze all network resources. The damages caused by the Morris computer virus were estimated at $96 millions.
To be able to spread the computer virus used errors in such operating systems as Unix for VAX and Sun Microsystems. There were a number of other interesting ideas used by the virus - for example it could pick user passwords.
The upcoming flu season and H1N1 may still be on a lot of people's minds, but there is another potentially more dangerous form of virus that lurks on the edge of our society. Computer viruses have been around less than half a century but the annual costs of controlling their spread are in the billions. Here is a list of the most dangerous computer viruses in history: