Class: Brakeman::CheckYAMLParsing

Inherits:
BaseCheck
  • Object
show all
Defined in:
lib/brakeman/checks/check_yaml_parsing.rb

Instance Method Summary collapse

Instance Method Details

#disabled_xml_dangerous_types? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/brakeman/checks/check_yaml_parsing.rb', line 91

def disabled_xml_dangerous_types?
  if version_between? "0.0.0", "2.3.14"
    matches = tracker.find_call(target: :"ActiveSupport::CoreExtensions::Hash::Conversions::XML_PARSING", method: :delete)
  else
    matches = tracker.find_call(target: :"ActiveSupport::XmlMini::PARSING", method: :delete)
  end

  symbols_off = false
  yaml_off = false

  matches.each do |result|
    arg = result[:call].first_arg

    if string? arg
      if arg.value == "yaml"
        yaml_off = true
      elsif arg.value == "symbol"
        symbols_off = true
      end
    end
  end

  symbols_off and yaml_off
end

#disabled_xml_parser? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/brakeman/checks/check_yaml_parsing.rb', line 50

def disabled_xml_parser?
  if version_between? "0.0.0", "2.3.14"
    #Look for ActionController::Base.param_parsers.delete(Mime::XML)
    matches = tracker.find_call(target: :"ActionController::Base.param_parsers", method: :delete)
  else
    #Look for ActionDispatch::ParamsParser::DEFAULT_PARSERS.delete(Mime::XML)
    matches = tracker.find_call(target: :"ActionDispatch::ParamsParser::DEFAULT_PARSERS", method: :delete)
  end

  unless matches.empty?
    mime_xml = s(:colon2, s(:const, :Mime), :XML)

    matches.each do |result|
      if result[:call].first_arg == mime_xml
        return true
      end
    end
  end

  false
end

#enabled_yaml_parser? ⇒ Boolean

Look for ActionController::Base.param_parsers = :yaml in Rails 2.x apps

Returns:

  • (Boolean) 


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# File 'lib/brakeman/checks/check_yaml_parsing.rb', line 74

def enabled_yaml_parser?
  matches = tracker.find_call(target: :'ActionController::Base.param_parsers', method: :[]=)

  mime_yaml = s(:colon2, s(:const, :Mime), :YAML)

  matches.each do |result|
    if result[:call].first_arg == mime_yaml and
      symbol? result[:call].second_arg and
      result[:call].second_arg.value == :yaml

      return true
    end
  end

  false
end

#run_check ⇒ Object 



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# File 'lib/brakeman/checks/check_yaml_parsing.rb', line 8

def run_check
  return unless version_between? "0.0.0", "2.3.14" or
                version_between? "3.0.0", "3.0.18" or
                version_between? "3.1.0", "3.1.9" or
                version_between? "3.2.0", "3.2.10"

  unless disabled_xml_parser? or disabled_xml_dangerous_types?
    new_version = if version_between? "0.0.0", "2.3.14"
                    "2.3.15"
                  elsif version_between? "3.0.0", "3.0.18"
                    "3.0.19"
                  elsif version_between? "3.1.0", "3.1.9"
                    "3.1.10"
                  elsif version_between? "3.2.0", "3.2.10"
                    "3.2.11"
                  end

    message = msg(msg_version(rails_version), " has a remote code execution vulnerability. Upgrade to ", msg_version(new_version), " or disable XML parsing")

    warn :warning_type => "Remote Code Execution",
      :warning_code => :CVE_2013_0156,
      :message => message,
      :confidence => :high,
      :gem_info => gemfile_or_environment,
      :link_path => "https://groups.google.com/d/topic/rubyonrails-security/61bkgvnSGTQ/discussion",
      :cwe_id => [20]
  end

  #Warn if app accepts YAML
  if version_between?("0.0.0", "2.3.14") and enabled_yaml_parser?
    message = "Parsing YAML request parameters enables remote code execution: disable YAML parser"

    warn :warning_type => "Remote Code Execution",
      :warning_code => :CVE_2013_0156,
      :message => message,
      :confidence => :high,
      :gem_info => gemfile_or_environment,
      :link_path => "https://groups.google.com/d/topic/rubyonrails-security/61bkgvnSGTQ/discussion",
      :cwe_id => [20]
  end
end