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.
READ MOREBitcoin mining using other people's resources. The brightest idea that a person who wants to have a bitcoin can do. Imagine how much hashes they can get if they successfully installed those malwares on other peoples computers.