MyDoom was a mass mailing virus that caused an awful lot of damage.
Even though it was designed primarily to be distributed via email, it also successfully spread itself across a great number of computers by infecting programs stored in the shared folder of the Peer2Peer software KaZaA.
First detected in 2004, MyDoom impacted Internet access by around ten percent and caused some website access to be reduced by as much as fifty per cent.
If MyDoom was able to infect a machine it then looked for email addresses from any contact lists it could find and sent itself to all of those addresses.
It was reported that during the first few days of being detected around 10% of all email messages sent contained the MyDoom virus.
After it’s initial release it took about a month for the spread to be brought into check.
Read more : Malware That Changed The World