Monday, July 25, 2016

Feedly:SANS Internet Storm Center, InfoCON: green. Python Malware - Part 4, (Mon, Jul 25th)

from SANS Internet Storm Center, InfoCON: green

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

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