How to research programs?

Question

Programming

Dear toasterovtsy there was a question of the following character. There are self-written programs on android (and a little on java), how to investigate them for vulnerabilities. How to use these vulnerabilities for your own selfish purposes))))) Let's suppose this program hangs in memory, interacts with the server and does something there, how to wedge into its work? How to make it so that it would fall or give incorrect data, or, for example, give out to an attacker (that is, me) what it should not give out? Or, for example, if it works with admin rights, then somehow hacking this program could also seize these same rights and pass off its actions as the actions of this program?
The fact is that in IB I am an oak oak, but after writing a couple of my little applications I became interested in how to break them, so I ask you to tell me the literature or courses where you can get the necessary knowledge.

Answer 1

Start by studying the OS architecture and software architecture for this OS.

Answer 2

It's very simple: if you want a "secure" application, make it client-server. And there already focus on server protection. It's just that the client is difficult to protect: what is only one decompilation of the application worth.