It's no longer news that android devices due to its openness can easily be exploited by those that are rich knowledgewisely(if theres any word like this) in such fields.
A recent research has showed that millions of android devices have been affected/infected with a malware.
How It Happened/Happens
These days there seems to be alot of websites coming out on a daily basis to announce one promo or the other where you will be promised some cryptocurrencies when you help promote them through referrals or through giving tasks But in reality what the main of aims of these websites are is to hijack your android smartphone and then turn it into a mining machine for their own personal gains without your knowledge. It uses your phones CPU and memory without your concern for mining activities which you don't benefit from.
Solution
What we android users have to do especially those into cryptocurrency to avoid falling victim includes:
1.Avoid such sites offering heaven and earth when you engage them, especially these new ones coming in
2.Read the reviews of other people who had interacted with them before businesswisely
3.Do not deal with websites that doesn't use SSL(HTTPS) You can confirm this through the web address box on your web browser.
4.Always update your system or apps, make sure your browsers are up to date because their developers could release newer versions with better patches to fix such issues.
5.The last but not the least, make use of strong antiviruses to detect such headaches. Lol.
One a serious note, please always use anti viruses, they come in handy in such situations. I use avast antivirus in case you need one installed you can check it out on Google Play Store.