I made several apps for myself, with simple REST api's, and when I needed to blacklist a user, or something else "administrator-like-actions", I just do it directly in the MySQL database.
Now I'm working on a project for a client, who wants an administration interface, where he can do these kinds of actions.
Instead of reinventing the wheel, I'm sure that I can build on top of an existing piece of software, but I can't find anything. I might be searching with the wrong keywords.
I think October CMS, could do the trick for me, but I am not sure yet... :-)