Answer: The Morris Worm
As far as security holes and malicious software are concerned, the Morris worm is downright legendary. Developed by Robert Tappan Morris while studying at Cornell University, the worm unleashed a perfect storm on the computer world and Morris' life.
Morris was a computer geek with a pedigree ̵
The worm had what turned out to be a critical mistake. Machines could be infected several times, which led to a kind of mirror effect. Once the worm was in the wild, it quickly spread and frequently reinfected the same machines. In essence, The Morris Worm was the first, albeit random, denial-of-service attack, as the enormous amount of reinfections and network traffic brought thousands of machines to their knees. The infection was unprecedented and many system administrators have tried to keep their systems online (usually with little success).
The Morris worm served the security community as a great wake up call. A doctoral student's antics had shut down a significant portion of the Internet, caused tens of millions of dollars in damage, and showed how fragile the burgeoning global network really was.
Morris' reward for unleashing such a firestorm on the Internet was a site in history as the first person to be prosecuted under the Computer Fraud and Abuse Act of 1986 (an amendment to the existing Computer Fraud Act that entered the The 1984 Law on Comprehensive Crime). This act was expanded and incorporated into the Patriot Act, but in its original form it was primarily intended to provide the US Federal Government with an opportunity to prosecute individuals who have abused federal computers. Many computers that Morris had crippled were part of federal institutions, and as such, he was found guilty and sentenced to three years probation, 400 hours of community service, and a $ 10,050 fine plus the cost of his oversight.
If you're curious where Mr. Morris is now, he's a professor of electrical engineering and computer science at MIT – it's nice to see they have no grudge.
Picture by Trevor Blackwell / Wikimedia.