A teenager was sentenced Friday to 1½ years in prison for unleashing a variant of the "Blaster" Internet worm (search) that crippled 48,000 computers in 2003.

Jeffrey Lee Parson (search), 19, of Hopkins, Minn., will serve his time at a low-security prison and must perform 10 months of community service. He had faced up to 10 years in prison, but the judge took pity on the teen, saying his neglectful parents were to blame for the psychological troubles that led to his actions.

"[The Internet] has created a dark hole, a dungeon if you will, for people who have mental illnesses or people who are lonely," U.S. District Judge Marsha Pechman (search) said. "I didn't see any parent standing there saying, 'It's not a healthy thing to lock yourself in a room and create your own reality."'

Defense lawyers said Parson feared leaving the house and his parents provided little support. He pleaded guilty last summer to one count of intentionally causing or attempting to cause damage to a protected computer.

Parson created a Blaster version that launched a distributed denial-of-service attack against a Microsoft Windows update Web site as well as personal computers. Blaster and its variants, also known as the LovSan virus, crippled networks worldwide.

Parson's lawyers said he has made great strides since his arrest. They also credited him with making a Seattle School District video warning teens of the dangers of Internet vandalism.

Parson apologized to the court and to Microsoft, saying, "I know I've made a huge mistake and I hurt a lot of people and I feel terrible." He will still have to pay restitution to Microsoft and to people whose commuters were affected in an amount to be determined at a hearing next month.

Parson was charged in Seattle because Microsoft is based in suburban Redmond.