https://arstechnica.com/information-technology/2019/08/google-play-app-with-100-million-downloads-executed-secret-payloads/

The perils of Google Play are once again on display with the discovery of an app with 100 million downloads that contained a malicious component that downloaded secret payloads onto infected Android devices.

Throughout most of its life, CamScanner was a legitimate app that provided useful functions for scanning and managing documents, researchers from antivirus provider Kaspersky Lab said on Tuesday. To make money, the developers displayed ads and offered in-app purchases.