[Android Central Question]

I switched from an iPhone to Pixel 3 in December, this is my first non apple phone and I'm quite clueless. The only reason I had used apple up until now is the safety factor, it significantly limits you but seems to prevent malware (did I mention clueless?).

I have been extremely careful about what apps I download, only getting them from google's play store and reading reviews first. I do not use my phone to search the web much, but when I do I'm using the chrome app and googling for something.

I normally use 300-400 mb of data a month. I got a message this morning that I'd gone over my data limit of 10 gb. I use an app called Brain.FM (one that transferred over from my iphone). My phone showed that it pulled over 9gb of data. When I pulled up the details, it had pulled 3gb at 4am, 2gb at 7am, 3gb at 8am etc. (exact times but not exact amounts). While I'd been running the app on wifi overnight, I'd closed out of it at 6:30am and I have background data turned off.

I ended up deleting the app because I had no idea how this occurred. An hour after I'd deleted the app, something pulled another 1gb of data. While my phone had previously shown Brain.FM as the app using the data, this time it showed a jump in data usage, but did not attribute it to any app.

I have my phone set so any updates occur via wifi, and I have no idea what could have used that much data for an update.

My assumption was I ended up with some kind of malware and it only looked like the Brain.FM app was using the data. I've factory reset my phone and did not use the backup to restore it because it had backed up since the issue started. I did allow it to connect to my gmail account to pull contacts etc so hopefully that wasn't infected. I have also set a data limit of 50mb so hopefully if it happens again the data shuts off long before there is an issue. (I did not know this was an option before today.)

Can anyone help me understand what happened and how so I can prevent it from happening again? I had read that I don't need a security app because google has plenty built in, should I get some kind of extra security?

The Brain.FM app, should I avoid it? I have used it every day for over a year, granted only a few months on android, and have never had an issue before.

Is there a different app I should have been avoiding? I had instagram, podcast addict (paid), fitbit, jigsaw puzzle app, accuweather and about a half dozen others that all transferred over from my iphone. The podcast and weather apps were the only ones that I got on my pixel, the others transferred over from my iphone.

Thank you for any insight and advice!

[VidJunky]

Wow, well first let me thank you for including so much detail. Android is a fairly safe OS and you are taking the right steps to keep your device safe, only downloading from the Play Store and reading reviews are two of the things I implore more people to do. Meanwhile, you mentioned that apps are set to only update over WiFi, but what about your Podcast app, Google backup, and that Brain app, music streaming I assume? If your usage says it was the Brain app it probably was and I say this because Android apps can't backdoor into apps that way. The apps I mentioned could send and receive large data files but you should have control over WiFi vs Data. The two things that strike me about this is your mention that your phone disconnected from WiFi and the data turned on... There is a setting in your WiFi settings that says, if the WiFi signal is weak switch to data, but I don't think even that setting would turn on your data if it was off. Also there is a sleep option that will disconnect your WiFi if your device hasn't used the internet in awhile. I'm not sure of the timing on this or if you can vary it, so say if no packets have been sent or received in 2 hours put the WiFi to sleep. I'm also assuming that nothing happened to your router, such as a power flicker or outage or even an internet outage that would have caused it to disconnect from your device. That's just an assumption though. I have unlimited so I kind of don't worry about data too much but I had that PodCast Addict and honestly didn't like it. It did all kinds of odd things, most of which were connection and streaming related. But again it shouldn't be able to show up as another app. Those 3 things are really bothering me. The data usage when data should be off, the WiFi turning off, and all of the data being shown as this one app. I'd start with what could turn off the WiFi. Looking in the WiFi settings for the weak signal option and the sleep option. Data Shouldn't work like Do Not Disturb and enable its self randomly even after a period of time but you didn't put the phone in Airplane Mode so you might check the data settings as well.

[Rukbat]

@VidJunky, you're correct - Brain.FM is a music streaming app. And if the OP just deleted the icon from the home screen, and didn't uninstall it, it's probably still running.

Unlike iPhones, the icon you tap to run an app in an Android phone is only a shortcut to the actual app. Deleting the shortcut doesn't uninstall the app. You have to go into Settings, then Apps % Notifications, find the app and uninstall it. (Or just don't use it that much - constantly running a music streaming app will use a lot of data.)