I have a related question. I'm using a rooted phone (with a custom arq51 rom). Concerned about spying malware I have the "Avast Mobile Security" app installed, less for its virus protection than for the granular firewall that it has. With this firewall I block internet or outside data access to all programs I do not think need to have it to work (games and the like). For similar privacy reasons I do not sync any app with the cloud.
My questions, because I am not knowledgeable in Linux or Android, are:
1. Even though the firewall blocks access to the internet or the phone network, can apps still send out data through some other hidden mechanism in Android?
2. Of course I cannot use that type of firewall for apps like browsers, email, text, etc. How does one prevent these apps from sending out data to somewhere I did not authorize?
I do not get ads in my notification bar but anyway ran Ad detector and its scan found nothing bad. But, another similar app found several of my phone apps apparently use admob (which I have turned off in the Google Play options). Is there a simple way to block admob access (and similar spy networks) to apps other than Google Play without running still another blocking app?
I am currently not getting ads, but am concerned about data going out without my knowing it because I know of no way to tell what is going out in android.