85 fake apps in Google Play that collectively have been installed nine million times by users all over the world came with an adware strain capable of pouring fullscreen adverts at regular intervals or when the user unlocks the device. Malware researchers at Trend Micro say that the adware (detected as AndroidOS_HidenAd) distributed this way could hide itself and run in the background. The most popular of the fraudulent apps was Easy Universal TV Remote, last updated on November 12, 2018, with an average of 3.9 stars from 132,000 Android users.
Source: https://www.bleepingcomputer.com/news/security/85-adware-apps-in-google-play-installed-9-million-times/