At the dawn of the XXIst century, I LOVE YOU worm infected tens of millions of computers. As a fairly simple worm, I LOVE YOU presented itself as an incoming email with “I love you” in its subject line and infected the machine of users who opened the attachment. It then mailed itself to all of the contacts found on the infected user’s system.
Intriguing feature: While the author’s motivation clearly wasn’t about money, the damages were: When the dust settled, I LOVE YOU had cost companies around the world between $5 and $10 billion. Much of that cost can be attributed to the time spent “cleaning” infected machines.
More of the history of viruses is posted at Help Net Security. Link -via the Presurfer