Malware
BRATA
aka AmexTroll · Copybara
According to Cleafy, the victim's Android device is factory reset after the attackers siphon money from the victim's bank account.
BRATA, also known as AmexTroll, Copybara, is a Android malware family.
Background
Cleafy notes that once the attackers drain funds from the victim's bank account, the victim's Android device is factory reset. This both diverts the user's attention from the theft and wipes traces or footprints that could be valuable to forensic analysts.
Source: Malpedia (Fraunhofer FKIE).