# Xamarin

## General

Las aplicaciones desarrolladas con Xamarin agrupan su código compilado en Dynamically Linked Libraries (.dll), las cuales pueden almacenarse en el directorio `app-decompiled/unknown/assemblies/` de forma independiente, comprimidas mediante LZ4 / XALZ o bien integradas conjuntamente en un archivo denominado `assemblies.blob`.

## Obtención de DLLs

```sh
apktool d application.apk -o app-decompiled
ls -l app-decompiled/unknown/assemblies/

file app-decompiled/unknown/assemblies/<file.dll>
     file.dll: PE32 executable (DLL) (console) Intel 80386 Mono/.Net assembly, for MS Windows
```

## Descompresión de DLLs (LZ4 / XALZ)

```sh
apktool d application.apk -o app-decompiled
ls -l app-decompiled/unknown/assemblies/

file app-decompiled/unknown/assemblies/<file.dll>
     file.dll: Sony PlayStation Audio
    
python Xamarin_XALZ_decompress.py app-decompiled/unknown/assemblies/<file.dll> file_decompressed.dll

file file_decompressed.dll
     file_decompressed.dll: PE32 executable (DLL) (console) Intel 80386 Mono/.Net assembly, for MS Windows
```

## Obtención de DLLs desde archivo .blob

```sh
apktool d application.apk -o app-decompiled

ls -l app-decompiled/unknown/assemblies/
     assemblies.blob
     assemblies.manifest

file app-decompiled/unknown/assemblies/assemblies.blob
     assemblies.blob: Sony PlayStation Audio

pyxamstore unpack -d app-decompiled/unknown/assemblies/
ls -l out
```

## Herramientas

* [dnSpy](https://github.com/dnSpy/dnSpy)
* [ILSpy](https://github.com/icsharpcode/ILSpy) (Windows) / [AvaloniaILSpy](https://github.com/icsharpcode/AvaloniaILSpy) (Linux/Unix)
* [pyxamstore](https://github.com/jakev/pyxamstore)
* [Xamarin\_XALZ\_decompress.py](https://github.com/x41sec/tools/blob/master/Mobile/Xamarin/Xamarin_XALZ_decompress.py)


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