An American who helped a New Zealand hacker has been sentenced to 90 days in prison and five years of probation.


Ryan Goldstein of Philadelphia has been sentenced to 90 days in a halfway house followed by 180 days of house arrest after helping Owen Thor Walker mount an electronic attack on an internet server.


Goldstein, who told the judge he had suffered a ‘computer addiction' since he was 12, was also fined US$30,000 (NZ$50,400) and prohibited from using a computer for five years except for work or school activities.


Walker gained unauthorised access to a University of Pennsylvania computer server by using a botnet. He was allegedly the mastermind of a botnet coding group and received just under $40,000 for his part in the attacks, which included a global adware scheme and the collapse of a computer server at the American university.


Assistant US Attorney Michael Levy claimed Goldstein and Walker used the university computer system as a staging ground for a 50,000-computer attack. Investigators said that after Goldstein was arrested, he began cooperating with authorities, and his information led to Walker, who installed malicious software on 1.3 million computers worldwide.


Walker was was discharged without conviction at the High Court in Hamilton last July after admitting six cyber crime charges - both crown lawyer Ross Douch and defence lawyer Tony Balme told the court that police were interested in using Walker's skills on the right side of the law. Justice Judith Potter ordered Walker to pay $9526 as his half share of the damage caused to the university computer and other costs of $5000, and ordered him to hand over his computer-related assets to police.