Trojan Development Kits (TDKs) are available from hacking forums and through advertisements on a social networking messaging service popular in China. The free app is no different from any other Android app apart from the fact that it creates malware. To generate the malware, all the user needs to do is choose what customization they want by filling out the on-screen form. The app allows the user to start an online chat with the apps developer where they can arrange a one-time payment. Once the user has subscribed, they can continue with the process, making as many variants as they desire.”]
Source: https://grahamcluley.com/android-ransomware-construction-kit/