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Fuzzer Engine

Fuzzer engine consists of two parts.

  • fuzzer, the actual fuzzer to fuzz the Android native system services.
  • manager, it manages to fuzz Android native system services automatically to some extent.
    • push fuzzer and data to smartphone
    • sync crash logs, e.g., logcat logs, tombstone logs
    • flash smartphone
    • etc.

Prepare Data

Before fuzzing, we should prepare data used by the fuzzer, including

  • interface model, locates in workdir/interface-model-extractor/model
  • various seeds, located in seed, e.g.,
    • files
      • media files, located in seed/files/media. You can add media files according to your demand, e.g., mp3, mp4.
      • apk files, located in seed/files/apk. You can add apk files according to your demand. Here we give a simple file, which is from https://www.appsapk.com/compass/.
      • misc files, located in seed/files/misc. You can add misc files according to your demand.
    • media URLs, located in seed/media_url_list.txt. You can add URLs according to your demand.
    • package name list, located in seed/package_list.txt. You can use adb shell pm list packages |cut -f 2 -d : to get the packages installed on your device.
    • permission list, locates in seed/permission_list.txt. You could use adb shell pm list permissions -g |sed "s/ permission://g" | grep -v "All Permissions:\|group:\|ungrouped:\|^$" > permission_list.txt to collect the permissions provided by your device.

Build Fuzzer

Before building the fuzzer, please modify the option include_dirs in fuzzer-engine/fuzzer/Android.bp. You need to change "out/target/product/taimen/obj/STATIC_LIBRARIES/libwificond_ipc_intermediates/aidl-generated/include" to the corresponding directory of your target mobile phone. This directory is a relative directory related to the AOSP directory. Besides, it is generated when compiling the AOSP.

Here we provide a handful template setup.template.sh to build the fuzzer. You can create setup.sh according to your environment. Then you can build the fuzzer with ASan enabled as follows.

# create a symbolic link inside the AOSP_ASan dir.
cd /path/to/aosp_asan
ln -s /path/to/fans/fuzzer-engine/setup.sh .
# build
bash
source setup.sh

Test Fuzzer

Currently, fuzzer supports several options as follows

$ ./native_service_fuzzer --help
Usage: ./native_service_fuzzer [OPTION]

  --log_level       specify the log level of fuzzer
  --interface       specify the target interface to fuzz
  --transaction     specify the target transaction to fuzz
  --help            help manual

For example, after pushing fuzzer and related data to the /data/fuzzer dir of the device, we can use the following commands to test IDrm interface and IDrm::13-13 transaction correspondingly. Note that we can not specify the interface option and transaction option at the same time.

adb shell "./data/fuzzer/native_service_fuzzer --log_level=debug --interface=IDrm"
adb shell "./data/fuzzer/native_service_fuzzer --log_level=debug --transaction=IDrm::13-13"

Here we also provide a handful template test_fuzzer.template.sh to test the fuzzer to check if it works as expected. You can create test_fuzzer.sh according to your environment. In the script,

  • $1 should be the device serial
  • If you want to push data and fuzzer to the device, you should set $2 to "push".

Here is an example of how to use test_fuzzer.sh.

# push data and test fuzzer.
# XXXXXXXXXXXXXX should be the serial number of your device
sh test_fuzzer.sh XXXXXXXXXXXXXX push

Besides, if you find some problems with fuzzer, you can also use debug_fuzzer.sh to debug fuzzer.

Run Fuzzer Manager

Please refer to the Fuzzer Manager.