Using social engineering tricks, a developer can create an app
that tricks users into tapping a specifically-crafted app popup
window (called toast view), making it a gateway for varied
threats.This attack, dubbed tapjacking, takes advantage of a
specific vulnerability in Android user interaction (UI)
component. This technique is not very complicated but has
serious security implications to Android users. But before we
get into the details of tapjacking, let me explain briefly where
this UI vulnerability is stemming from. Introduction to app
activity Android displays UI elements in the unit of activities.
An activity is a system component that takes up the whole screen
size and can hold many different views, which is a rectangle
area shown on the device’s screen. Below is an example of an
activity that contains two views namely (1) text view, which is
where a user can encode a text and (2) button that a user clicks
(or taps). As seen below, an activity may take up the whole
screen even if a large part of it i