The teenager accused of releasing a version of the Blaster worm last year has bargained with officials to reduce his jail time.
In a Seattle court, the 19-year-old from Minnesota, Jeffrey Lee Parson, pleaded guilty to causing damage to a protected computer, so he could reduce his sentence.
Parson could have been sentenced for 10 years, but now faces between 18 and 37 months in jail and a large fine.
Parson constructed the Blaster-B worm and released it in August last year. The worm started a denial-of-service attack on a Microsoft website.