According to internet activists Anonymous Norway, the so-called distributed denial of services (DDoS) attacks were perpetrated by a group calling itself DotNetFuckers.
Among the organizations targeted by the hackers were Norwegian security police service PST, DnB bank, a range of Norwegian IT news websites, national lottery firm Norsk Tipping, Britain's Serious Organised Crime Agency (SOCA) and German tabloid Bild.
The National Criminal Investigation Service (NCIS) on Wednesday revealed it had arrested two suspects, an 18-year-old and a 19-year-old, in connection with attacks carried out in recent weeks.
The pair have been charged with aggravated criminal damage, an offence that carries a maximum sentence of six years, NCIS said.
“We have arrested the two people we believe were most central to these attacks, but we are still hoping to speak to more people,” said prosecutor Erik Moestue.
The hackers are suspected of deliberately overloading the servers of the sites in question, causing serious financial damage in certain cases.
The police were aided in their investigations by the Norwegian branch of the Anonymous collective, which posted the identities of the suspects online.
Irritated by the activities of DotNetFuckers, Anonymous published images of the hackers along with their names, addresses, schools, mobile phone numbers, email addresses, Facebook pages and online aliases used on services like YouTube, Spotify and Google+.
“DotNetFuckers consists of a group of 14-16-year-olds with very limited computer skills,” Anonymous said.
“We have not yet discovered a motive for the attacks, so we’re assuming that they’re doing it to get a kick or to destroy things for others. They’re a gang of boys”.
Anonymous said it would continue to publish more information about the group of young hackers.