For internet blocking, AFWall+[0] is a fork of DroidWall which seems to be under active development.

Unfortunately, XPrivacy is not available on F-Droid, but anyone who is able to get it building and submitted to F-Droid would have my gratitude.

[0] - https://f-droid.org/repository/browse/?fdfilter=droidwall&fd...

For XPrivacy, it's a little scary to install. The warnings about making your phone unbootable, for example.

EDIT: I went ahead and installed it. No problems. I must say, though, I wouldn't call it easy to use. There are a lot of options.

If my device was rooted, wouldn't the attacker be smart enough to circumvent this?

The vulnerability is the attacker's way into your system. If you've rooted and blocked that vulnerability, then the attacker can't use that way into your system.