For millions of people buying inexpensive smartphones in developing countries where privacy protections are usually low, the convenience of on-the-go internet access could come with a hidden cost: preloaded apps that harvest users’ data without their knowledge.
One such app, included on thousands of Chinese-made Singtech P10 smartphones sold in Myanmar and Cambodia, sends the owner’s location and unique-device details to a mobile-advertising firm in Taiwan called General Mobile Corp., or GMobi. The app also has appeared on...