If your Android phone is feeling sluggish all of a sudden, there’s a chance it could be infected with malware that sneakily mines cryptocurrencies like Bitcoin.

Researchers from cyber security firm Trend Micro found the JsMiner and CpuMiner malware strains lurking behind at least three apps, with the malicious code leeching an infected phone’s processing power to mine Monero coins.

The malware hid behind seemingly tame free apps, including a Wi-Fi scanner and a religious prayer app.

But once downloaded the malware loaded JavaScript code from mining tool provider Coinhive to start mining Monero coins in the background, while adversely affecting an infected phone’s performance and battery life.

“These threats highlight how even mobile devices can be used for cryptocurrency mining activities, even if, in practice, the effort results in an insignificant amount of profit,” explained Trend Micro’s threat researchers. “Users should take note of any performance degradation on their devices after installing an app.”

The infected apps have since been pulled from the Play Store by Google, but it remains unclear as to how many Android devices the malware strains managed to infect and if they were able to generate a bountiful amount of Monero coins for the cyber crooks behind the malware spread.

Cryptocurrency mining can be a lucrative undertaking, with event the likes of The Pirate Bay exploring ways to use miners to semi-legitimately make money without relying on website adverts.

So it’s worth being extra vigilant when downloading Android apps, even those that look fairly legitimate, and keep an eye out for any sudden drops in your phone’s performance and battery life as they’re ell-tale signs that something nasty is lurking in the background on your handset.

Related: Are Bitcoin’s days numbered?

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