MASTG-TOOL-0104: hermes-dec
Hermes-dec is a tool for reverse-engineering compiled hermes bytecode for both Android and iOS apps. It supports decompilation and disassembly of Hermes VM bytecode (HBC) format, typically seen in apps developed in React Native.
If you encounter either of the following files during static analysis, hermes-dec provides a way to recover a legible version of the file's contents:
- index.android.bundle
- main.jsbundle
Use file to check the type and confirm you are dealing with actual Hermes bytecode:
$ file main.jsbundle
main.jsbundle: Hermes JavaScript bytecode, version 90
If instead you see that it's a plain text file, it can be opened with any text editor and hermes-dec isn't needed:
$ file main.jsbundle
main.jsbundle: Unicode text, UTF-8 text
You can try using hermes-dec in situations where you are doing static analysis on a React Native mobile app, and react-native-decompiler fails.