An issue was discovered on BLU Advance 5.0 and BLU R1 HD devices with Shanghai Adups…

Summary

An issue was discovered on BLU Advance 5.0 and BLU R1 HD devices with Shanghai Adups software. The com.adups.fota.sysoper app is installed as a system app and cannot be disabled by the user. In the com.adups.fota.sysoper app's AndroidManifest.xml file, it sets the android:sharedUserId attribute to a value of android.uid.system which makes it execute as the system user, which is a very privileged user on the device. The app has an exported broadcast receiver named com.adups.fota.sysoper.WriteCommandReceiver which any app on the device can interact with. Therefore, any app can send a command embedded in an intent which will be executed by the WriteCommandReceiver component which is executing as the system user. The third-party app, utilizing the WriteCommandReceiver, can perform the following actions: call a phone number, factory reset the device, take pictures of the screen, record the screen in a video, install applications, inject events, obtain the Android log, and others. In addition, the com.adups.fota.sysoper.TaskService component will make a request to a URL of http://rebootv5.adsunflower.com/ps/fetch.do where the commands in the String array with a key of sf in the JSON Object sent back by the server will be executed as the system user. Since the connection is made via HTTP, it is vulnerable to a MITM attack.