In the first half of 2018, criminals managed to steal and extort $1.1 billion in cryptocurrencies, with the most popular target being cryptocurrency exchanges (27%).

Most of the attacks were committed in the United States with 24 cases. China is on the second place with 10 cases, the third place is occupied by Great Britain with 8 cases, says the study, completed by the cybersecurity company Carbon Black. Its experts estimated that there are now approximately 12,000 trading platforms in the darkweb with 34,000 relevant proposals for hackers.

"It's surprising just how easy it is without any tech skill to commit cybercrimes like ransomware," Carbon Black Security strategist Rick McElroy told CNBC. "It's not always these large nefarious groups, it's in anybody's hands."

The cost of malware required for attacks vary around $224, but there are proposals starting from $1.04.

Darkweb is part of the World Wide Web, but access to it is provided only through special software that allows users to remain anonymous. It is often impossible to track someone in the darkweb.

Hacker attacks, involving cryptocurrency thefts, are committed both by organized cartels and criminal groups, and by individuals,for example, unemployed computer network engineers who want to earn money.

"You have nations that are teaching coding, but there's no jobs," McElroy said. "It could just be two people in Romania needing to pay rent."

The most popular cryptocurrency in extortion attacks is Monero (44%). BTC and ETH are less popular, with 10% and 11% respectively.