If someone has rooted my phone, can I flas the phone to remove hack? Factory reset does nothing.

[coffee1707]

My husband and I are having the same problem. I've been trying to get help with this issue for months. I've had people tell me I wasn't hacked and made me feel like I was completely crazy. I now have screen shots of a lot of things. To prove I am not crazy.
I have factory reset our phones and before doing so closed email accounts along with the Samsung cloud accounts. When factory resetting our phones we just had to set up a lock code or password whichever one you wanted then when the phone boots back up afterwards I've set up all new accounts. Nothing seems to matter. Because as soon as we are all set up and think finally it's over, then guess again. I'm not sure about rooting a phone but that is next on my list of things to try.
The things that are happening on our phones mainly my husband's phone, is the Hangouts are set up with Pop or IMAP accounts set up where we cannot receive our mail, Google drives, Google pictures and clouds are full of hidden files, Google pay accounts are set up, Samsung links are activity sending links from people in some kind of secret language. There will be things in our clipboard that are just unbelievable.
In files I have read on my phone through file viewer it has how the program is computing. The steps it is taking and the failed steps and then finally the successful steps. I am by no means a computer person and neither is my husband, but over these past few months I have learned a lot. When the program that is on our phones gets a successful hack then there is some kind of coin it collects. If anyone who doubts this and wants to see for themselves, I have nothing to hide and you are welcome to connect with me and see for yourself. But I would say do it at your own risk.
Also I have no internet. We have phone data. Samsung has remotely worked on our phones through the tech support team and their only advice was to get new phones. I have a Galaxy J7 and my husband has a J3 prime.

 

[Rukbat]

1. Flash the stock ROM to the phone. Do not keep your apps and data, do a full flash (In other words, if there's a CSC_HOME file and another CSC file, don't use the CSC_HOME file). That will put the phone back to the state it was i at the time you first got it (unless the current version is later than the version it had when you got it, of course).

2. Rooting is basically adding 1 file to the phone, named su. Apps that you've been running before you root aren't affected, only apps that call that additional file will even notice that the phone is rooted (and none of the apps that run when the phone hasn't been rooted do that).

As for the rest, you may see things in the clipboard that aren't text so, to you, they're "unbelievable", but to someone used to working deep down in the operating system, they may appear to be something perfectly normal - but something that the normal user doesn't see. The same with Drive, Photos and your cloud accounts - an Android phone is full of hidden files normally, and if you're syncing a folder that has them, those files will sync. It's also full of pictures that should be hidden (and not get backed up), but some apps aren't written properly, so if you see pictures that you've seen on websites, backed up to Drive or Photos, that's normal (for an improperly written app - not hacked, just written by someone who doesn't know how to write Android apps).

So back up anything you don't want to lose (see Backing up an Android Device if you have questions) and flash the stock ROM. (See [Samsung] How to flash Stock ROM via ODIN for that. Samsung phones are particularly easy to flash. Scary the first time you do it, waiting 10 minutes or so for the phone to fully come back to life, but after the first few times, very boring.)

 

[Mooncatt]

If you have screenshots of the suspected hacking, it would be very helpful to upload them here so we can see what you're seeing and give more direct advice.

 

[belodion]

Yes, we'd like to see the screenshots. Here's how to post them: https://forums.androidcentral.com/showthread.php?t=413366