blutter: Flutter Mobile Application Reverse Engineering Tool

by ddos · April 16, 2025

B(l)utter

Flutter Mobile Application Reverse Engineering Tool by Compiling Dart AOT Runtime

Currently, the application supports only Android libapp.so. Also, the application currently works only against recent Dart versions.

Install

This application uses the C++20 Formatting library. It requires a very recent C++ compiler such as g++>=13, Clang>=15.

Debian Unstable (gcc 13)

Install build tools and dependencies: apt install python3-pyelftools python3-requests git cmake ninja-build \
build-essential pkg-config libicu-dev libcapstone-dev

Windows

Install latest Microsoft C/C++ Compiler with CMake tools
Install required libraries (libcapstone and libicu4c): python scripts\init_env_win.py
Start x64 Developer Command Prompt

macOS Ventura (clang 15)

Install XCode
Install clang 15 and the required tools: brew install llvm@15 cmake ninja pkg-config icu4c capstone
pip3 install pyelftools requests

Clone the repo:

git clone https://github.com/worawit/blutter.git

Use

The blutter.py will automatically detect the Dart version from the flutter engine and call executable of blutter to get the information from libapp.so.

If the blutter executable for required Dart version does not exists, the script will automatically checkout Dart source code and compiling it.

Output files

asm/* libapp assemblies with symbols
blutter_frida.js the frida script template for the target application
objs.txt complete (nested) dump of Object from Object Pool
pp.txt all Dart objects in Object Pool

Directories

bin contains blutter executables for each Dart version in “blutter_dartvm<ver><os><arch>” format
blutter contains source code. need building against Dart VM library
build contains building projects which can be deleted after finishing the build process
dartsdk contains checkout of Dart Runtime which can be deleted after finishing the build process
external contains 3rd party libraries for Windows only
packages contains the static libraries of Dart Runtime
scripts contains python scripts for getting/building Dart