Fuzzer for libupdate_engine_android

Table of contents

• updateEngine_downloadAction_fuzzer

Fuzzer for download_action

Plugin Design Considerations

The fuzzer plugin for libupdate_engine_android is designed based on the understanding of the library and tries to achieve the following:

Maximize code coverage

The configuration parameters are not hardcoded, but instead selected based on incoming data. This ensures more code paths are reached by the fuzzer.

libupdate_engine_android supports the following parameters:

1. Version (parameter name: version)
2. Already_Applied (parameter name: already_applied)
3. Is_Resume (parameter name: is_resume)
4. Interactive (parameter name: interactive)

This also ensures that the plugin is always deterministic for any given input.

Maximize utilization of input data

The plugin feeds the entire input data to the libupdate_engine_android module. This ensures that the plugin tolerates any kind of input (empty, huge, malformed, etc) and doesnt exit() on any input and thereby increasing the chance of identifying vulnerabilities.

Build

This describes steps to build updateEngine_downloadAction_fuzzer binary.

Android

Steps to build

Build the fuzzer

  $ mm -j$(nproc) updateEngine_downloadAction_fuzzer

Steps to run

To run on device

  $ adb sync data
  $ adb shell /data/fuzz/${TARGET_ARCH}/updateEngine_downloadAction_fuzzer/updateEngine_downloadAction_fuzzer

References:

• http://llvm.org/docs/LibFuzzer.html
• https://github.com/google/oss-fuzz