Stockholm: Hooked-in Sweden is becoming a haven for cryptojackers siphoning off capacity and energy to mine for digital currencies.

The number of such attacks surged an estimated 10,100 per cent in the biggest Nordic economy in the fourth quarter, about double the jump globally, according to Symantec Corp’s 2018 Internet Security Threat Report.

And the thing is, it’s not even illegal. “Cryptojacking where you install a program without my permission and steal capacity is very impolite,” said Ola Rehnberg, head of Nordic Enterprise Security at Symantec. “But not a crime in itself. So the hacker takes a very small risk.”

But it does cost society. Coinmining can slow down devices, overheat batteries, and in some cases, render devices unusable. For enterprises, the virtual gold rush can put corporate networks at risk and inflate cloud central processing unit usage, adding cost.

Rehnberg said the whole thing has become “an industry” where “hackers work 9-5, Monday to Friday and go on Christmas holidays.”

The coinmining trend in Sweden is partly due to the infiltration of websites, meaning that a website will steal capacity as long as you’re on it. But it can also happen through the more traditional route, where software is installed on a computer.

Sweden is a good target because there’s great interest in Bitcoin, but also because the country is rich and people have fast, modern computers.

“This is a race,” Rehnberg said. “A faster computer enables a higher reward.”

As digital currency prices soared the business has become very lucrative, though things could change rapidly.

“Then the bad guys will find other ways to earn money,” said Rehnberg. At some point in the future they will target your home, he said.