At the very end of a compiled PyInstaller executable, there is a small structure called the . This cookie contains a specific 8-byte magic string ( MEI\012\013\014\013 ), followed by the position of the embedded archive inside the file, the length of the archive, and the Python version flag.

Do not assume the file is a PyInstaller archive. You must verify what tool actually generated the binary.

Look for ASCII strings like MEI , pyinstaller , py2exe , or Nuitka . If you see cx_Freeze or no Python-related strings at all, pyinstxtractor will not work. 3. Extract Nested Installers