Bitcoin's booming value has driven a huge rise in crypto-currency themed malware, say security firms.
In one month, anti-malware software company Malwarebytes said it stopped almost 250 million attempts to place coin-mining malware on to PCs.
Symantec said it had seen a "tenfold" increase in the amount of malicious code connected with crypto-cash.
Cyber-thieves are using both dedicated software, hacked websites and emails to snare victims.
Cashing in
"There's been a huge spike," said Candid Wuest, a threat researcher at online security firm Symantec, adding that it had been caused by the rapid increase in Bitcoin's value.
On 29 November, the value of one Bitcoin surpassed $10,000 (£7,943) - a massive increase on the $1,000 each one was worth at the start of 2017, although that figure has now fallen back sharply.
"With $10,000 being breached, and all the hype, a lot of people are trying to make money with crypto-coins," said Mr Wuest.
Most of the activity seen by Symantec and other security firms involves crypto-coins other than Bitcoin. This was because it took a huge amount of computer power to produce or "mine" bitcoins.
By contrast, he said, mining other crypto-coins such as Monero could be done on desktops, laptops and even smartphones.
Many of these alternative coins had risen in value alongside Bitcoin, said Mr Wuest.
