Over the past year, the privacy-focused cryptocurrency monero has grown by more than 3,000%, and in recent weeks soared to new heights, trading above $330 for the first time amid promises by its developers of lower transaction fees.

The price surge, which echoes the recent explosion in bitcoin’s value, also coincides with another trend: hackers are quietly hijacking significant numbers of computers to run code that mines the currency. In recent months, crypto-jacking malware has reportedly been secretly mining monero as people watched videos on websites owned by Showtime and Ultimate Fighting Challenge and as customers at Starbucks cafes in Argentina used Wi-Fi. According to Reuters, the Russian pipeline giant Transneft said last week that it had discovered software surreptitiously mining the cryptocurrency on some of its computers. “It could have a negative impact on the productivity of our processing capacity,” Transneft vice-president Vladimir Rushailo reportedly told company executives.

The three-year-old currency’s privacy-focused design has also made it handy for darknet drug deals and money laundering. In September the Milan-based security firm Neutrino reported that someone had moved payouts that had been collected in May’s widespread WannaCry ransomware attack from bitcoin to monero, which is presumably easier to surreptitiously convert into fiat currency. (In June, a leaked NSA memo linked the WannaCry worm to North Korea.)

Still, monero’s developers are hoping that the currency’s ease of mining and privacy features—the very features that make it so appealing to…