python.cryptography.security.insecure-hash-algorithms.insecure-hash-algorithm-sha1

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Detected SHA1 hash algorithm which is considered insecure. SHA1 is not collision resistant and is therefore not suitable as a cryptographic signature. Use SHA256 or SHA3 instead.

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Defintion

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rules:
  - id: insecure-hash-algorithm-sha1
    patterns:
      - pattern: cryptography.hazmat.primitives.hashes.$SHA(...)
      - metavariable-pattern:
          metavariable: $SHA
          pattern: |
            SHA1
      - focus-metavariable: $SHA
    fix: |
      SHA256
    message: Detected SHA1 hash algorithm which is considered insecure. SHA1 is not
      collision resistant and is therefore not suitable as a cryptographic
      signature. Use SHA256 or SHA3 instead.
    metadata:
      source-rule-url: https://github.com/PyCQA/bandit/blob/d5f8fa0d89d7b11442fc6ec80ca42953974354c8/bandit/blacklists/calls.py#L59
      cwe:
        - "CWE-327: Use of a Broken or Risky Cryptographic Algorithm"
      owasp:
        - A03:2017 - Sensitive Data Exposure
        - A02:2021 - Cryptographic Failures
      bandit-code: B303
      references:
        - https://www.schneier.com/blog/archives/2012/10/when_will_we_se.html
        - https://www.trendmicro.com/vinfo/us/security/news/vulnerabilities-and-exploits/sha-1-collision-signals-the-end-of-the-algorithm-s-viability
        - http://2012.sharcs.org/slides/stevens.pdf
        - https://pycryptodome.readthedocs.io/en/latest/src/hash/sha3_256.html
      category: security
      technology:
        - cryptography
      subcategory:
        - vuln
      likelihood: LOW
      impact: MEDIUM
      confidence: MEDIUM
      license: Commons Clause License Condition v1.0[LGPL-2.1-only]
    severity: WARNING
    languages:
      - python

Examples

insecure-hash-algorithms.py

# cf. https://github.com/PyCQA/bandit/blob/b78c938c0bd03d201932570f5e054261e10c5750/examples/crypto-md5.py

from cryptography.hazmat.primitives import hashes

# ruleid:insecure-hash-algorithm-sha1
hashes.SHA1()
# ok:insecure-hash-algorithm-sha1
hashes.SHA256()
# ok:insecure-hash-algorithm-sha1
hashes.SHA3_256()