Android Hacker's Handbook

Chapter 11Attacking the Radio Interface Layer

The Radio Interface Layer, RIL in short, is the central component of the Android platform that handles cellular communication. The Radio Interface Layer provides an interface to the cellular modem and works with the mobile network to provide mobile services. The RIL is designed to operate independent of the cellular modem chips. Ultimately the RIL is responsible for things such as voice calls, text messaging, and mobile Internet. Without the RIL, an Android device cannot communicate with a cellular network. The RIL is, in part, what makes an Android device a smartphone. Today, cellular communication is no longer limited to mobile phones and smartphones because tablets and eBook readers come with built-in, always-on mobile Internet. Mobile Internet is the responsibility of the RIL, and therefore, the RIL is present on most Android devices.

This chapter shows you how the RIL works and how it can be analyzed and attacked. It methodically introduces you to the different components of RIL and how they work together. The attack part of this chapter focuses on the Short Messaging Service (SMS) and specifically how to fuzz SMS on an Android device. The first half of the chapter provides an overview of the Android RIL and introduces the SMS message format. The second half of the chapter takes a deep dive into instrumenting the RIL to fuzz the SMS implementation of Android. When you reach the end of this chapter you will be armed with the ...