Police say the botnet skimmed millions from bank accounts
A New Zealand teenager accused of being the ringleader of an international cyber-crime network has been convicted.
Owen Thor Walker, 18, admitted six charges of using computers for illegal purposes and will be sentenced in May.
Police allege the group infiltrated more than one million computers and used them to skim at least $20.4m (£10.3m) from private bank accounts.
He was detained last November as part of an FBI investigation into global botnets - networks of hijacked PCs.
A botnet can be controlled over the internet by a single computer.
It installs malicious software on PCs around the world to collect information such as login names, bank account details and credit card numbers.
Walker pleaded guilty to charges of accessing a computer for dishonest purposes, interfering with computer systems, possession of software for committing crime and accessing computer systems without authorisation, the New Zealand Press Association said.
New Zealand police said he had begun committing the crimes at school, and had designed an encrypted virus that was undetectable by anti-virus software.
It allowed him access to usernames and passwords as well as credit card details, and was used by others to commit the frauds.
Walker faces up to five years in prison for several of the charges, but Judge Arthur Tompkins indicated he was not considering a custodial sentence.
Walker was detained in New Zealand's North Island city of Hamilton and is reported to have Asperger's syndrome - a neurobiological disorder which can result in deficiencies in social skills.
Although patients have normal intelligence, some may have exceptional talent in a specific area.