Symantec found eight apps on Microsoft’s app store that mine Monero without the user’s knowledge. The apps which included those for computer and battery optimization tutorial, internet search, web browsers, and video viewing and download—came from three developers: DigiDream, 1clean, and Findoo. In total, we discovered eight apps from these developers that shared the same risky behavior. After further investigation, we believe that all these apps were likely developed by the same person or group.
Users may get introduced to these apps through the top free apps lists on the Microsoft Store or through keyword search. The samples we found run on Windows 10, including Windows 10 S Mode.
As soon as the apps are downloaded and launched, they fetch a coin-mining JavaScript library by triggering Google Tag Manager (GTM) in their domain servers. The mining script then gets activated and begins using the majority of the computer’s CPU cycles to mine Monero for the operators. Although these apps appear to provide privacy policies, there is no mention of coin mining on their descriptions on the app store.
The apps were published between April and December 2018, with most of them published toward the end of the year. Even though the apps were on the app store for a relatively short period of time, a significant number of users may have downloaded them. Although we can’t get exact download or installation counts, we can see that there were almost 1,900 ratings posted for these apps. However, app ratings can be fraudulently inflated, so it is difficult to know how many users really downloaded these apps.