Are Android programs installed by themselves?

Question

Android

Hello! I have a Micromax A104 Canvas Fire 2 smartphone. After what point, applications began to install themselves (360 security lite, DU speedbooster). With the help of Clean Master, I found a folder with already downloaded .apk installers for 1.5 giga, deleted it. I deleted these 2 programs through the settings, but after a reboot they reappear. It seems to me that these 2 apk are located somewhere in the device's memory and are installed when the phone is turned on. Tell me how can I deal with this? dr. web didn't find anything((
upd:
I downloaded "Firewall without Root" to determine what is downloading all this garbage.
In general, it turns out that several strange services make a frequent request for Internet access - adobe air(has the rights to change system settings, access wi-fi, change or delete the contents of the sd card, get data about the status of the phone) and engrils (launch when the device is turned on, disable sleep mode, close other applications, unlimited Internet access, etc. ) .
All these .apk files are downloaded to the sdcard1 / DownloadProvider / download
adobe air folder (in small letters) I did not download and this was not in the system before.
engrils is trying to go to taobao ip (140.205.156.81)

Answer 1

The problem was solved by demolishing the factory firmware. This algorithm for downloading and installing applications was originally included in the factory firmware.

Answer 2

A little about what CleanMaster is: www.helpix.ru/appinion/201504/1178-clean_master-oc...
Such as yours is now common, they are looking for ways to fight and counteract. But, they say, it will be pichalko without root.