Threat Level: green Handler on Duty: Didier Stevens

SANS ISC: Python Malware - Part 4 - SANS Internet Storm Center SANS ISC InfoSec Forums


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Python Malware - Part 4

You don't always get a text file with source code when you extract Python code from a PyInstaller-produced EXE.

I produced the following Python code including shellcode, and generated an EXE with PyInstaller:

Then I extract the Python code:

This time, the extracted shellcode file doesn't contain Python source code:

It's actually compiled Python bytecode.

Add the following 8 bytes to the beginning of the file and save it as shellcode.pyc:

Now you can use a Python bytecode decompiler like Easy Python Decompiler:

Here is the recovered source code (shellcode.pyc_dis):

Didier Stevens
Microsoft MVP Consumer Security
blog.DidierStevens.com DidierStevensLabs.com

DidierStevens

296 Posts
ISC Handler

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