How can I stop rogue apps downloading themselves?

[Knobblywobbly]

Hi folks,
I hope you can help as this is getting on my nerves. My wife has a Cubot Echo phone running Android 6, which has been great until recently. Suddenly the phone started displaying pop-up ads so we assumed she had some form of malware. Rather than mess around I removed her microSD card and did a factory reset of her phone. We didn't restore any of her apps or data - instead we loaded them again.
She only has the following apps on her phone:

The Weather Channel
Whatsapp
Telegram
Facebook Messenger

All the above apps were downloaded from the Google Play Store.
A couple of days ago the adverts started again, but I also noticed that some downloads were occurring without any intervention from us. I have installed malwarebytes but it doesn't find anything. Automatic updating of apps is turned off in the Play Store. I've now installed AVG to see if it helps.

Is there any way to find out what is serving up these ads, and to stop this stuff automatically downloading to the phone? it's getting really, really annoying!!
TIA

 

[Knobblywobbly]

My wife has just come in saying that some more downloads have occurred. She now has build.app.signed.mfver and clock installed. Both of these have an Android icon next to them (presumable to try to fool us into thinking they are really part of the Android system).
I have installed Addons detector too, and it is now reporting system.app.android.lints and Fiverr.

 

[belodion]

Welcome.

None of the apps you list should cause direct trouble of that kind, so far as I can see - though one or more may be being used or exploited for that purpose - so presumably the cause of the trouble is system-deep. If you didn't put the cause of the trouble there, as you might have done if you'd installed something unpleasant, it must have been there when you bought the phone.

 

[Javier P]

There are a few reports of Cubot phones auto downloading apps and it's possible that this is done by the stock firmware. This is one example.

https://forums.androidcentral.com/showthread.php?p=6132700

 

[Knobblywobbly]

There are a few reports of Cubot phones auto downloading apps and it's possible that this is done by the stock firmware. This is one example.

https://forums.androidcentral.com/showthread.php?p=6132700

Thanks for the link. It appears that the culprit was an OTA update from a couple of months ago. I've just checked and there is a new update with a patch to stop malware. I'm installing that now so will see if that cures it!

 

[Javier P]

Thanks for the link. It appears that the culprit was an OTA update from a couple of months ago. I've just checked and there is a new update with a patch to stop malware. I'm installing that now so will see if that cures it!

Let's hope that update fixes the problem. Keep us posted.