The cyber-scammers infected millions of computers with a so-called 'ransomware' virus that accused victims of viewing child pornography and demanded a fine payment, officials said Wednesday.
The virus locked computers in over 30 countries, mostly in Europe, and it demanded payment of a fine of €100 to return control to users, Europol director Rob Wainwright told a news conference in Madrid.
The message generated by the virus used the logo of the national police force and the language of the country where the computer was based, he added.
"This is an example of the evolving nature of cybercrime online, of how cybercrime is becoming more sophisticated," Wainwright said.
Police detained 10 people – six Russians, two Ukrainians and two Georgians – last week on Spain's Costa del Sol as part of the investigation, said Spain's secretary of state for security, Francisco Martinez.
The suspected author of the virus and the leader of the operation, a 27-year-old Russian national, was detained in Dubai in December, he added.
The investigation remains open and further arrests are likely, he said.
The authorities said the group raised millions of euros with its scam but could not yet offer a precise amount.
About three percent of those whose computers were infected by the virus paid the fine that was demanded.
Ransomware viruses, which try to make victims pay an on-the-spot fine, are becoming more prevalent but most strains simply accuse people of pirating movies or music. Others scramble data that is only unscrambled when a fee is paid.