As I said in this post, my father is very careless about online security. Besides what I already said on that post, yesterday I saw in his android that the permission to install of third-party apps are enabled, and he confirmed that he disabled this protection to install something that he even remember what is it (I think this was recently, because he did not want to answer anything about the app's nature or when he did this). I have already talk to him about his negligence, but nothing appears to has effect.
I'm worried because my mother accesses her bank account here (in her own PC, not in my father's PC). Some members in this forum recommended to me create a separate network for me and my mother's devices, but I am have difficult to find information about how do this and I don't have knowledge about networks.
I would like to know:
How likely is to a virus (or any malicious program/app) spread through devices on the same network?
What type of malicious application can do that?
It is possible for me to identify if that occurs without doing a long search?
I'm accepting other suggestions about what I can do.
Obs: All devices here are windows or android.