Check Point mobile threat researchers recently detected a severe infection in 36 Android devices belonging to a large telecommunications company and a multinational technology company. In all instances, the malware was not downloaded to the device as a result of the users use, it arrived with it. The malicious apps were not part of the official ROM supplied by the vendor, and were added somewhere along the supply chain. Most of the malware found to be pre-installed on the devices were info-stealers and rough ad networks.”]
Source: https://blog.checkpoint.com/2017/03/10/preinstalled-malware-targeting-mobile-users/