Japan, US, Australia, India and France are the top five countries affected by bitcoin-mining malware, according to a new study by security company Trend Micro.

Trend Micro detected 3 malware called BKDR_BTMINE, TROJ_COINMINE and HKTL_BITCOINMINE through its Smart Protection Network, its global threat intelligence service. The malware is used by criminals to mine bitcoins from infected machines, and has infected more than 12,000 PCs around the world.

“Cybercriminals will continue to find ways to monetize their malicious activities,” Roland Dela Paz, Trend Micro threat response engineer said. “Bitcoin-mining malware attacks are just another means for them to do so. Bitcoin mining may have earned cybercriminal attention due to the fact that it represents a direct source of income.”

According to Trend Micro, its findings should be a reminder of the importance of keeping bitcoin wallets secure by separating the bitcoin wallet and managing the bitcoin account offline. Trend Micro said that bitcoins should be used and managed “with the same caution and prudence that applies to real currency – cash.”

With bitcoins there is no reversal of charges so if it is compromised by hackers, there is no way to get it back, especially since there is no central authority or regulation.

Last week, the Reserve Bank of India issued a public notice warning users to stay away from digital currencies. Two of the countries bitcoin exchanges were raided by India’s Enforcement Directorate, and several bitcoin exchanges suspended operations.

Recently, a number of dedicated hosting providers reported to be running low on dedicated servers, attributing the shortages to an increase in customers buying cheap servers for digital currencies.