A 19-year-old Minneapolis man pleaded guilty Wednesday to unleashing part of the MSBlast worm attack that wreaked havoc on the Internet last summer.

Jeffrey Lee Parson admitted creating the "MSBlast.B" variant, also called "teekids," by modifying the original version of the worm and adding a backdoor that granted him control of infected computers, federal prosecutors said.

"Sending out a computer worm may be viewed as a harmless prank," John McKay, a U.S. attorney, said in a statement. "But the damage to individual computer users is very real, and the penalties are also very real."

Sentencing is scheduled for Nov. 12 in Seattle before U.S. District Judge Marsha Pechman. Parson could face between 18 and 37 months in prison on the charge of intentionally causing damage to a networked computer, plus possible restitution in the millions of dollars