The ZTE ZMAX Champ Android device with a build fingerprint of ZTE/Z917VL/fortune:6.0.1/MMB29M/20170327.120922:user/release-keys contains a pre-installed platform app with a package name of com.android.zte.hiddenmenu (versionCode=23, versionName=6.0.1) that contains an exported broadcast receiver app component named com.android.zte.hiddenmenu.CommandReceiver that is accessible to any app co-located on the device. This app component, when it receives a broadcast intent with a certain action string, will write a non-standard (i.e., not defined in Android Open Source Project (AOSP) code) command to the /cache/recovery/command file to be executed in recovery mode. Once the device boots into recovery mode, it will crash, boot into recovery mode, and crash again. This crash loop will keep repeating, which makes the device unusable. There is no way to boot into an alternate mode once the crash loop starts.

The ZTE Blade Vantage Android device with a build fingerprint of ZTE/Z839/sweet:7.1.1/NMF26V/20180120.095344:user/release-keys, the ZTE Blade Spark Android device with a build fingerprint of ZTE/Z971/peony:7.1.1/NMF26V/20171129.143111:user/release-keys, the ZTE ZMAX Pro Android device with a build fingerprint of ZTE/P895T20/urd:6.0.1/MMB29M/20170418.114928:user/release-keys, and the ZTE ZMAX Champ Android device with a build fingerprint of ZTE/Z917VL/fortune:6.0.1/MMB29M/20170327.120922:user/release-keys contain a pre-installed platform app with a package name of com.android.modem.service (versionCode=25, versionName=7.1.1; versionCode=23, versionName=6.0.1) that exports an interface to any app on co-located on the device. Using the exported interface of the com.android.modem.service app, any app can enable and obtain certain log files (modem and logcat) without the appropriate corresponding access permissions. The modem logs contain the phone number and full text body of incoming and…