Early this year a piece of malicious computer code burrowed its way into the website of Britain’s National Health Service. The script acted as a parasite, harnessing the computing power of unsuspecting visitors and using it to generate digital currency, in a practice known as “cryptojacking”.
When computers confirm transactions on a blockchain, the infrastructure that records cryptocurrency transfers, they are rewarded in digital money. As cryptocurrencies such as bitcoin and monero have soared in value, hackers have increasingly engaged in mass theft of processing power for this energy-intensive procedure of “mining” them.
Companies from carmaker Tesla to insurer Aviva have been stung by cryptojacking schemes, which can slow computers and increase server bills. One crypto-mining script lurks on more than 35,000 websites, according to data from PublicWWW, a search engine for internet source code.