Class: Brakeman::CheckSymbolDoS

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

Constant Summary collapse

UNSAFE_METHODS = 
[:to_sym, :literal_to_sym, :intern, :symbolize_keys, :symbolize_keys!]

Instance Method Summary collapse

Instance Method Details

#check_unsafe_symbol_creation(result) ⇒ Object 



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# File 'lib/brakeman/checks/check_symbol_dos.rb', line 19

def check_unsafe_symbol_creation result
  return unless original? result

  call = result[:call]

  if result[:method] == :literal_to_sym
    args = call.select { |e| sexp? e }
  else
    args = [call.target]
  end

  if input = args.map{ |arg| has_immediate_user_input?(arg) }.compact.first
    confidence = :high
  elsif input = args.map{ |arg| include_user_input?(arg) }.compact.first
    confidence = :medium
  end


  if confidence
    return if safe_parameter? input.match
    return if symbolizing_attributes? input

    message = msg("Symbol conversion from unsafe string in ", msg_input(input))

    warn :result => result,
      :warning_type => "Denial of Service",
      :warning_code => :unsafe_symbol_creation,
      :message => message,
      :user_input => input,
      :confidence => confidence,
      :cwe_id => [20]
  end
end

#run_check ⇒ Object 



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# File 'lib/brakeman/checks/check_symbol_dos.rb', line 10

def run_check
  return if rails_version and rails_version >= "5.0.0"
  return if tracker.config.ruby_version and tracker.config.ruby_version >= "2.2"

  tracker.find_call(:methods => UNSAFE_METHODS, :nested => true).each do |result|
    check_unsafe_symbol_creation(result)
  end
end

#safe_parameter?(input) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/brakeman/checks/check_symbol_dos.rb', line 53

def safe_parameter? input
  if call? input
    if node_type? input.target, :params
      input.method == :[] and
      symbol? input.first_arg and
      [:controller, :action].include? input.first_arg.value
    else
      safe_parameter? input.target
    end
  else
    false
  end
end

#symbolizing_attributes?(input) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/brakeman/checks/check_symbol_dos.rb', line 67

def symbolizing_attributes? input
  input.type == :model and
    call? input.match and
    input.match.method == :attributes
end