Class: Brakeman::CheckRegexDoS

Inherits:
BaseCheck 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
  ]
}

Constants inherited from BaseCheck

BaseCheck::CONFIDENCE

Constants included from Util

Util::ALL_COOKIES, Util::ALL_PARAMETERS, Util::COOKIES, Util::COOKIES_SEXP, Util::DIR_CONST, Util::LITERALS, Util::PARAMETERS, Util::PARAMS_SEXP, Util::PATH_PARAMETERS, Util::QUERY_PARAMETERS, Util::REQUEST_COOKIES, Util::REQUEST_ENV, Util::REQUEST_PARAMETERS, Util::REQUEST_PARAMS, Util::REQUEST_REQUEST_PARAMETERS, Util::SAFE_LITERAL, Util::SESSION, Util::SESSION_SEXP

Constants inherited from SexpProcessor

SexpProcessor::VERSION

Instance Attribute Summary

Attributes inherited from BaseCheck

#tracker, #warnings

Attributes inherited from SexpProcessor

#context, #env, #expected

Instance Method Summary collapse

Methods inherited from BaseCheck

#add_result, inherited, #initialize, #process_array, #process_cookies, #process_default, #process_dstr, #process_if, #process_params

Methods included from Messages

#msg, #msg_code, #msg_cve, #msg_file, #msg_input, #msg_lit, #msg_plain, #msg_version

Methods included from Util

#array?, #block?, #call?, #camelize, #class_name, #constant?, #contains_class?, #cookies?, #dir_glob?, #false?, #hash?, #hash_access, #hash_insert, #hash_iterate, #integer?, #kwsplat?, #literal?, #make_call, #node_type?, #number?, #params?, #pluralize, #rails_version, #regexp?, #remove_kwsplat, #request_env?, #request_value?, #result?, #safe_literal, #safe_literal?, #safe_literal_target?, #set_env_defaults, #sexp?, #string?, #string_interp?, #symbol?, #template_path_to_name, #true?, #underscore

Methods included from ProcessorHelper

#current_file, #process_all, #process_all!, #process_call_args, #process_call_defn?, #process_class, #process_module

Methods inherited from SexpProcessor

#in_context, #initialize, #process, processors, #scope

Constructor Details

This class inherits a constructor from Brakeman::BaseCheck

Instance Method Details

#process_call(exp) ⇒ Object


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# File 'lib/brakeman/checks/check_regex_dos.rb', line 59

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[1..-1]

  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
    end
  end
end

#run_checkObject

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