"At first, we had no idea who sent the worm," Allman says. "It was quite clear it was intentional, but we had no clue who it was or why it was sent. There was a sense of panic at the time, which was unfortunate but very understandable."

The attack disrupted Internet connectivity for several days, prompting some organizations including the US Department of Defense to unplug their Internet gateways to prevent infection.

"People disconnected from the network because they were afraid of what might happen," Allman says. "One of the ironies is that disconnecting from the 'Net also broke down our major communications channel. That's why it took longer to get everyone back up."

At the time the worm was launched, the Internet had no commercial traffic or Web sites. Damage was limited to researchers at government agencies, universities and a handful of corporations who used the network to exchange e-mail and transfer files. Nonetheless, the attack was covered widely by mainstream publications such as The New York Times.

"The Morris worm was the first time most people ever heard the word 'Internet,'" Bellovin says. "For most people, it was a novelty, a strange and wondrous world ... and one rogue operator could take it down. Nobody had ever heard of the Internet unless you were a computer scientist."

For some, the Morris worm was a career-changing event. Eugene Spafford was an assistant professor of computer science at Purdue University when Morris hit. Today, Spafford is executive director of Purdue's Center for Education and Research in Information Assurance and Security, and he is an internationally recognized authority on Internet security issues.

"I had been told by my advisors there was no future in applied computer security research," Spafford says. "When this happened, suddenly a whole lot of people realized that the development of systems had leapfrogged the controlled, mainframe environment and a different kind of security model needed to be observed.... We needed a more engineering approach, a more practical approach."

The Great Worm

The Morris worm was the first major worm attack, and it was dubbed "The Great Worm" in a reference to Tolkein.