Class: Brakeman::CheckRegexDoS

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

Overview

This check looks for regexes that include user input.

Constant Summary collapse

ESCAPES = 
{
  s(:const, :Regexp) => [
    :escape,
    :quote
  ]
}

Instance Method Summary collapse

Instance Method Details

#process_call(exp) ⇒ Object 



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# File 'lib/brakeman/checks/check_regex_dos.rb', line 60

def process_call(exp)
  if escape_methods = ESCAPES[exp.target]
    if escape_methods.include? exp.method
      return exp
    end
  end

  super
end

#process_result(result) ⇒ Object

Warns if regex includes user input



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# File 'lib/brakeman/checks/check_regex_dos.rb', line 28

def process_result result
  return unless original? result

  call = result[:call]
  components = call.sexp_body

  components.any? do |component|
    next unless sexp? component

    if match = has_immediate_user_input?(component)
      confidence = :high
    elsif match = has_immediate_model?(component)
      match = Match.new(:model, match)
      confidence = :medium
    elsif match = include_user_input?(component)
      confidence = :weak
    end

    if match
      message = msg(msg_input(match), " used in regular expression")

      warn :result => result,
        :warning_type => "Denial of Service",
        :warning_code => :regex_dos,
        :message => message,
        :confidence => confidence,
        :user_input => match,
        :cwe_id => [20, 185]
    end
  end
end

#run_check ⇒ Object

Process calls



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# File 'lib/brakeman/checks/check_regex_dos.rb', line 17

def run_check
  Brakeman.debug "Finding dynamic regexes"
  calls = tracker.find_call :method => [:brakeman_regex_interp]

  Brakeman.debug "Processing dynamic regexes"
  calls.each do |call|
    process_result call
  end
end