If the user has a relatively recent version of the operating system, meaning Android 8 or higher, which doesn’t hand out root permissions willy-nilly, then it loads additional modules for the Triada Trojan. These modules, among other things, can buy premium subscriptions and download other malware.
If the device is older, running Android 6 or 7, and without security updates installed (or in some cases not even released by the vendor), and thus more easily rootable, it could be the xHelper Trojan. Removing this beast is a real challenge; even a factory reset won’t do it. Armed with root access, xHelper lets attackers do almost anything they want on the device.