Android’s accessibility services are meant to help disabled people interact with their smartphone devices by integrating verbal feedback, voice commands and more in their apps. Many popular Android apps use the accessibility API to legitimately provide users with benefits, but over the past few months, we have seen a series of malware, including DoubleLocker ransomware, SVPeng, and BankBot, misusing this feature to infect people. Google now appears to be putting an end to apps that use this feature outside of their intended purpose.
Source: https://thehackernews.com/2017/11/android-accessibility-services.html