python.aws-lambda.security.tainted-pickle-deserialization.tainted-pickle-deserialization

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Avoid using pickle, which is known to lead to code execution vulnerabilities. When unpickling, the serialized data could be manipulated to run arbitrary code. Instead, consider serializing the relevant data as JSON or a similar text-based serialization format.

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Defintion

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rules:
  - id: tainted-pickle-deserialization
    mode: taint
    pattern-sources:
      - patterns:
          - pattern: event
          - pattern-inside: |
              def $HANDLER(event, context):
                ...
    pattern-sinks:
      - patterns:
          - pattern: $SINK
          - pattern-either:
              - pattern-inside: pickle.load($SINK,...)
              - pattern-inside: pickle.loads($SINK,...)
              - pattern-inside: _pickle.load($SINK,...)
              - pattern-inside: _pickle.loads($SINK,...)
              - pattern-inside: cPickle.load($SINK,...)
              - pattern-inside: cPickle.loads($SINK,...)
              - pattern-inside: dill.load($SINK,...)
              - pattern-inside: dill.loads($SINK,...)
              - pattern-inside: shelve.open($SINK,...)
    message: Avoid using `pickle`, which is known to lead to code execution
      vulnerabilities. When unpickling, the serialized data could be manipulated
      to run arbitrary code. Instead, consider serializing the relevant data as
      JSON or a similar text-based serialization format.
    metadata:
      owasp:
        - A08:2017 - Insecure Deserialization
        - A08:2021 - Software and Data Integrity Failures
      cwe:
        - "CWE-502: Deserialization of Untrusted Data"
      references:
        - https://docs.python.org/3/library/pickle.html
        - https://davidhamann.de/2020/04/05/exploiting-python-pickle/
      category: security
      technology:
        - python
        - aws-lambda
      cwe2022-top25: true
      cwe2021-top25: true
      subcategory:
        - vuln
      likelihood: MEDIUM
      impact: MEDIUM
      confidence: MEDIUM
      license: Commons Clause License Condition v1.0[LGPL-2.1-only]
    languages:
      - python
    severity: WARNING

Examples

tainted-pickle-deserialization.py

import _pickle
import cPickle
from dill import loads
import shelve


def lambda_handler(event, context):

  # ruleid: tainted-pickle-deserialization
  _pickle.load(event['exploit_code'])

  # ruleid: tainted-pickle-deserialization
  obj = cPickle.loads(f"foobar{event['exploit_code']}")

  # ruleid: tainted-pickle-deserialization
  loads(event['exploit_code'])(123)

  # ruleid: tainted-pickle-deserialization
  with shelve.open(f"/tmp/path/{event['object_path']}") as db:
    db['eggs'] = 'eggs'

  # ok: tainted-pickle-deserialization
  _pickle.loads('hardcoded code')

  # ok: tainted-pickle-deserialization
  code = '/file/path'
  cPickle.load(code)

  # ok: tainted-pickle-deserialization
  name = 'foobar'
  shelve.open(f"/tmp/path/{name}")