Unwanted Android apps keep reinstalling

​Recently, I received an Android phone through a special offer with a company called Testaankoop. The phone doesn't have a brand name printed on it, but mentions on the back the name of the company through which I received it. I noticed after a while that a certain "System update" and "SuperB Cleaner" app kept reinstalling, without me doing anything at all. I checked the package names and installed locations and, even though com.hermes.superb.booster (SuperB Cleaner) is a 'safe' application (i.e. it's something that isn't seen as a fake app), the 'System Update' (icon: a green Android thing) app got my attention: in the Link2SD app, I could see that it was installed under /data/app/com.android.ma.path4-1.apk. All system applications are usually installed under /system/app, so that was strange, especially if it is called "System Update" and when I tried to open it, it doesn't do anything. After a while, I get some ads popping up on my screen and I've also had the situation in which it prompted me to install an app requiring a lot of permissions (just like when you install an apk from your SD card) which I of course didn't install. I can successfully uninstall both the "System Update" and "SuperB Cleaner" app on my phone (and in adb), but once you connect the phone to the internet again, they are installed again. Therefore, I suspect a system application must be responsible for this. However, removing a system application is impossible for me as 1) I don't have a rooted phone and 2) if I were to root my phone, I have no idea what build I should choose from as I don't know what brand my phone is. Here is a list of all apps that are installed on my phone (including system ones) (I got this by using adb): package:/system/app/GoogleEars.apk=com.google.android.ears package:/system/priv-app/DefaultContainerService.apk=com.android.defcontainer package:/data/app/bbc.mobile.news.ww-1.apk=bbc.mobile.news.ww package:/system/priv-app/Contacts.apk=com.android.contacts package:/system/app/VoiceUnlock.apk=com.mediatek.voiceunlock package:/system/priv-app/TeleService.apk=com.android.phone package:/system/priv-app/JHLauncher3.apk=com.ibingo.launcher3 package:/system/app/Calculator.apk=com.android.calculator2 package:/data/app/de.hafas.android.sncbnmbs-2.apk=de.hafas.android.sncbnmbs package:/data/app/com.haxor-1.apk=com.haxor package:/system/app/HTMLViewer.apk=com.android.htmlviewer package:/system/framework/theme-res-mocha.apk=com.mediatek.theme.mocha package:/system/priv-app/GoogleLoginService.apk=com.google.android.gsf.login package:/system/app/Bluetooth.apk=com.android.bluetooth package:/system/priv-app/CalendarProvider.apk=com.android.providers.calendar package:/system/app/VoiceCommand.apk=com.mediatek.voicecommand package:/system/app/Calendar.apk=com.android.calendar package:/system/app/Browser.apk=com.android.browser package:/system/app/Music.apk=com.android.music package:/system/app/MTKLogger.apk=com.mediatek.mtklogger package:/mnt/asec/com.belgacom.fon-1/pkg.apk=com.belgacom.fon package:/system/priv-app/OneTimeInitializer.apk=com.android.onetimeinitializer package:/system/app/DownloadProviderUi.apk=com.android.providers.downloads.ui package:/system/app/DocumentsUI.apk=com.android.documentsui package:/system/priv-app/SharedStorageBackup.apk=com.android.sharedstoragebackup package:/system/app/Videos.apk=com.mediatek.videoplayer package:/system/app/FileManager.apk=com.mediatek.filemanager package:/system/priv-app/VpnDialogs.apk=com.android.vpndialogs package:/system/priv-app/Mms.apk=com.android.mms package:/system/app/Provision.apk=com.android.provision package:/system/priv-app/MediaProvider.apk=com.android.providers.media package:/data/app/com.google.android.marvin.talkback-2.apk=com.google.android.marvin.talkback package:/system/app/CertInstaller.apk=com.android.certinstaller package:/system/priv-app/CDS_INFO.apk=com.mediatek.connectivity package:/data/app/com.google.android.gms-1.apk=com.google.android.gms package:/system/priv-app/CallerID.apk=com.android.tools.callassistant package:/system/framework/theme-res-raspberry.apk=com.mediatek.theme.raspberry package:/system/app/MtkBt.apk=com.mediatek.bluetooth package:/system/app/BatteryWarning.apk=com.mediatek.batterywarning package:/system/priv-app/Settings.apk=com.android.settings package:/data/app/com.google.android.apps.pdfviewer-1.apk=com.google.android.apps.pdfviewer package:/system/app/Street.apk=com.google.android.street package:/data/app/com.google.android.apps.genie.geniewidget-1.apk=com.google.android.apps.genie.geniewidget package:/system/app/MTKThermalManager.apk=com.mediatek.thermalmanager package:/system/app/CalendarImporter.apk=com.mediatek.calendarimporter package:/system/priv-app/Velvet.apk=com.google.android.googlequicksearchbox package:/system/app/Gallery2.apk=com.android.gallery3d package:/system/app/DrmProvider.apk=com.android.providers.drm package:/system/app/VisualizationWallpapers.apk=com.android.musicvis package:/system/app/Exchange2.apk=com.android.exchange package:/system/app/EngineerModeSim.apk=com.mediatek.simmelock package:/system/app/LiveWallpapersPicker.apk=com.android.wallpaper.livepicker package:/system/framework/theme-res-mint.apk=com.mediatek.theme.mint package:/system/app/FWUpgradeProvider.apk=com.adups.fota.sysoper package:/system/app/PackageInstaller.apk=com.android.packageinstaller package:/system/priv-app/GoogleBackupTransport.apk=com.google.android.backuptransport package:/data/app/com.google.android.tts-1.apk=com.google.android.tts package:/system/app/TelephonyProvider.apk=com.android.providers.telephony package:/system/app/SchedulePowerOnOff.apk=com.mediatek.schpwronoff package:/system/app/CellConnService.apk=com.mediatek.CellConnService package:/system/app/PicoTts.apk=com.svox.pico package:/system/app/NoiseField.apk=com.android.noisefield package:/system/app/Email.apk=com.android.email package:/data/app/com.google.android.apps.maps-1.apk=com.google.android.apps.maps package:/system/priv-app/Dialer.apk=com.android.dialer package:/system/priv-app/FusedLocation.apk=com.android.location.fused package:/system/priv-app/BackupRestoreConfirmation.apk=com.android.backupconfirm package:/system/app/MagicSmokeWallpapers.apk=com.android.magicsmoke package:/system/priv-app/SettingsProvider.apk=com.android.providers.settings package:/data/app/com.yahoo.mobile.client.android.weather-1.apk=com.yahoo.mobile.client.android.weather package:/system/priv-app/DownloadProvider.apk=com.android.providers.downloads package:/system/app/FMRadio.apk=com.mediatek.FMRadio package:/system/app/MusicFX.apk=com.android.musicfx package:/system/app/PhaseBeam.apk=com.android.phasebeam package:/system/app/Todos.apk=com.mediatek.todos package:/system/app/SoundRecorder.apk=com.android.soundrecorder package:/system/priv-app/MtkVideoLiveWallpaper.apk=com.mediatek.vlw package:/data/app/com.microsoft.launcher-2.apk=com.microsoft.launcher package:/system/app/LatinIME.apk=com.android.inputmethod.latin package:/data/app/be.smartschool.mobile-2.apk=be.smartschool.mobile package:/data/app/com.buak.Link2SD-1.apk=com.buak.Link2SD package:/system/priv-app/GoogleOneTimeInitializer.apk=com.google.android.onetimeinitializer package:/system/priv-app/GooglePartnerSetup.apk=com.google.android.partnersetup package:/data/app/org.mozilla.firefox-1.apk=org.mozilla.firefox package:/system/app/Omacp.apk=com.mediatek.omacp package:/system/app/FactoryMode.apk=com.mediatek.factorymode package:/system/priv-app/ProxyHandler.apk=com.android.proxyhandler package:/system/priv-app/InputDevices.apk=com.android.inputdevices package:/system/app/HoloSpiralWallpaper.apk=com.android.wallpaper.holospiral package:/system/priv-app/GoogleFeedback.apk=com.google.android.feedback package:/system/priv-app/JHThemeApkManager.apk=com.nbbsw.theme package:/system/app/Stk1.apk=com.android.stk package:/data/app/com.android.ma.path4-1.apk=com.android.ma.path4 package:/system/app/UserDictionaryProvider.apk=com.android.providers.userdictionary package:/system/app/MTKAndroidSuiteDaemon.apk=com.mediatek.apst.target package:/system/priv-app/ConfigUpdater.apk=com.google.android.configupdater package:/system/app/PacProcessor.apk=com.android.pacprocessor package:/system/app/Galaxy4.apk=com.android.galaxy4 package:/system/app/DataTransfer.apk=com.mediatek.datatransfer package:/system/app/MtkWeatherProvider.apk=com.mediatek.weather package:/system/app/PrintSpooler.apk=com.android.printspooler package:/system/framework/mediatek-res.apk=com.mediatek package:/system/app/GoogleCalendarSyncAdapter.apk=com.google.android.syncadapters.calendar package:/system/framework/framework-res.apk=android package:/system/priv-app/ContactsProvider.apk=com.android.providers.contacts package:/system/app/Protips.apk=com.android.protips package:/system/app/MediaUploader.apk=com.google.android.apps.uploader package:/system/priv-app/ExternalStorageProvider.apk=com.android.externalstorage package:/system/app/ApplicationsProvider.apk=com.android.providers.applications package:/system/app/BasicDreams.apk=com.android.dreams.basic package:/data/app/be.vrt.mobile.android.deredactie-1.apk=be.vrt.mobile.android.deredactie package:/system/priv-app/PrivacyProtectionLock.apk=com.mediatek.ppl package:/data/app/com.android.vending-1.apk=com.android.vending package:/system/priv-app/SystemUI.apk=com.android.systemui package:/system/app/KeyChain.apk=com.android.keychain package:/system/app/JHTorch.apk=com.nbbsw.torch package:/data/app/com.google.android.gm-2.apk=com.google.android.gm package:/system/app/LiveWallpapers.apk=com.android.wallpaper package:/system/app/MtkWeatherWidget.apk=com.mediatek.appwidget.weather package:/system/app/EngineerMode.apk=com.mediatek.engineermode package:/system/app/FWUpgrade.apk=com.adups.fota package:/system/app/DeskClock.apk=com.android.deskclock package:/system/priv-app/GoogleServicesFramework.apk=com.google.android.gsf package:/system/priv-app/Keyguard.apk=com.android.keyguard package:/system/app/FaceLock.apk=com.android.facelock package:/system/app/ISmsService.apk=com.hissage package:/system/priv-app/Shell.apk=com.android.shell package:/system/app/ApplicationGuide.apk=com.mediatek.appguide.plugin package:/system/app/StkSelection.apk=com.mediatek.StkSelection package:/system/app/GoogleContactsSyncAdapter.apk=com.google.android.syncadapters.contacts I'm afraid that this might be some trojan or virus that might be stealing information. Does anyone know what I should do to stop this from happening?