AXML

AXML/ARSC: The Rosetta Stone for Android's Binary XML

Android doesn't speak in plain text XML. To save space and speed up parsing, it uses a compressed, obfuscated binary format (AXML) for its manifests and a complex table (ARSC) for its resources. axml is your translator.

This is a standalone, dependency-free, native Python library built to decode the secrets of Android's binary XML and resource files. It is a battle-hardened pillar of the new Androguard Ecosystem, providing the critical ability to turn machine-optimized formats back into human-readable intelligence.

This is a library for handling the AXML file format. AXML is the informal common name for the compiled binary XML data format used in Android app files. The Android Open Source Project does not seem to have named the format, other than referring to is as binary XML or compiled XML.So AXML stands for Android XML. The file format is based on compiling XML source into a binary format based on protobuf. There are a number of different Android XML file types that are compiled to AXML, these are generically known as Android Resources.

All of these files are included in the APK's ZIP package with the file extension .xml even though they are actually AXML and not XML.

Some specific data files, like String Resources and Style Resources, are instead compiled into a single file resources.arsc in its own data format, known as ASRC. AXML files often refer to values that are in resources.arsc.

The entry point for an app is the "app manifest" defines the essential data points that every app must have, like Package Name and Version Code, and includes lots of other metadata that describe the app. Every Android app file (APK) must include AndroidManifest.xml, which in the APK is the compiled binary AXML format, not XML, despite the file extension. The source code files for the binary app manifest file are also called AndroidManifest.xml, but they are actually XML. There can be multiple source files, but there is only ever one single compiled binary AndroidManifest.xml that is valid in the APK.

https://developer.android.com/guide/topics/manifest/manifest-intro#reference

Installation

If you would like to install it locally, please create a new venv to use it directly, and then:

$ git clone https://github.com/androguard/axml.git
$ pip install -e .

or directly via pypi:

$ pip install axml

Usage

Two new commands will be exported in your current environnement: axml and arsc, that will allow to read and display the corresponding files.

$ axml -i AndroidManifest.xml
$ arsc -i resources.arsc

API

The most easy way to use this project is probably directly via using the API:

>>> from axml.axml import AXMLPrinter
>>> from axml.arsc import ARSCPrinter
>>> AXMLPrinter(open("AndroidManifest.xml", "rb").read())
>>> obj
<axml.axml.printer.AXMLPrinter object at 0x76b5a34b0550>
>>> obj.package
'org.t0t0.androguard.TC'
>>> obj.androidversion
{'Code': '1', 'Name': '1.0'}

>>> obj = ARSCPrinter(open("test.arsc", "rb").read())
>>> obj
<axml.arsc.printer.ARSCPrinter object at 0x76b5a34b1310>
>>> obj.get_xml()
b'<resources>\n<public type="drawable" name="icon" id="0x7f020000"/>\n<public type="drawable" name="icon" id="0x7f020000"/>\n<public type="drawable" name="icon" id="0x7f020000"/>\n<public type="layout" name="main" id="0x7f030000"/>\n<public type="string" name="hello" id="0x7f040000"/>\n<public type="string" name="app_name" id="0x7f040001"/>\n</resources>\n'

AXML binary format

Some references about the binary AXML format:

• aapt2 compiles XML to protobuf-based AXML
• aapt2 source code
• aapt source code
• The binary format for AndroidManifest.xml is defined in ApkInfo.proto.