A security researcher has discovered four VPN apps that serve ads while running in the background and also on the home screen of Android smartphones in the latest case of adware found on the Google Play Store.
While researching suspicious Android VPN apps, Andy Michael found that Hotspot VPN, Free VPN Master, Secure VPN and Security Master by Cheetah Mobile were all showing full screen pop-up ads on his smartphone even though none of these apps were currently open.