Chinese company Shanghai Adups Technology Co. Ltd. (Adups in this article) had included malicious code in the firmware it sold to numerous Android phone manufacturers. Trustlook researchers have now released an in-depth report that expands on Kryptowire’s findings, after analyzing 1,904 device firmware images. The company believes that around 700 million Android devices may have the malicious code installed on them. The list of affected vendors also includes Ragentek, a company that developed and included its own backdoored firmware.
Source: https://www.bleepingcomputer.com/news/security/android-adups-backdoor-became-active-5-months-affected-43-phone-vendors/