Adversaries may delete, alter, or send SMS messages without user authorization. This could be used to hide C2 SMS messages, spread malware, or various external effects.
This can be accomplished by requesting the
SEND_SMS permissions depending on what the malware is attempting to do. If the app is set as the default SMS handler on the device, the
SMS_DELIVER broadcast intent can be registered, which allows the app to write to the SMS content provider. The content provider directly modifies the messaging database on the device, which could allow malicious applications with this ability to insert, modify, or delete arbitrary messages on the device.
|S0539||Red Alert 2.0|
Application vetting services could provide further scrutiny to applications that request SMS-based permissions.
Users should be encouraged to be very careful with what applications they grant SMS access to. Further, users should not change their default SMS handler to applications they do not recognize.
Users can view the default SMS handler in system settings.