Advertisements are effective income channels for free apps when tastefully done. However, some can get greedy and put ads practically everywhere. One of the most popular real estate in a smartphone is the lock screen as mobile users interact with it most of the time.
In 2018, over 10 million new malicious programs were detected each month. One of the most massive attacks was by Asacub. It targeted mobile users and was successful in infiltrating more than 250,000 unique victims.