mcp-server-semgrep/semgrep-rules/ruby/lang/security/bad-deserialization-yaml.yaml

MCP Server for Semgrep Integration - static code analysis with AI

rules:
- id: bad-deserialization-yaml
  patterns:
  - pattern: |
      YAML.load($...ARGS)
  - pattern-not: |
      YAML.load(..., safe: true, ...)
  - pattern-not: |
      YAML.load("...", ...)
  - pattern-not-inside: |
      YAML.load(..., File.read(...), ...)
  - pattern-not-inside: |
      $FILE = File.read(...)
      ...
      YAML.load(..., $FILE, ...)
  - pattern-not-inside: |
      $FILENAME = ...
      ...
      $FILE = File.read($FILENAME, ...)
      ...
      YAML.load(..., $FILE, ...)
  - pattern-not-inside: |
          YAML.load(..., $X.$Y(File.read(...)), ...)
  - pattern-not-inside: |
      YAML.load(..., $X.$Y(File.read(...)).$Z, ...)
  - pattern-not-inside: |
      $T = $MOD.$MET(File.read(...))
      ...
      YAML.load(..., $T, ...)
  - pattern-not-inside: |
      $T = $MOD.$MET(File.read(...))
      ...
      YAML.load(..., $T.$R, ...)
  fix: Psych.safe_load($...ARGS)
  message: >-
    Unsafe deserialization from YAML. Objects in Ruby can be serialized into strings,
    then later loaded from strings. However, uses of load and object_load can cause remote code execution.
    Loading user input with YAML can potentially be dangerous. Use JSON in a secure fashion instead.
    However, loading YAML from a static file is not dangerous and should not be flagged.
  metadata:
    cwe:
    - 'CWE-502: Deserialization of Untrusted Data'
    references:
    - https://groups.google.com/g/rubyonrails-security/c/61bkgvnSGTQ/m/nehwjA8tQ8EJ
    - https://github.com/presidentbeef/brakeman/blob/main/lib/brakeman/checks/check_deserialize.rb
    category: security
    technology:
    - ruby
    - yaml
    owasp:
    - A08:2017 - Insecure Deserialization
    - A08:2021 - Software and Data Integrity Failures
    cwe2022-top25: true
    cwe2021-top25: true
    subcategory:
    - audit
    likelihood: LOW
    impact: HIGH
    confidence: LOW
  languages:
  - ruby
  severity: ERROR