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, Util::SIMPLE_LITERALS

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

#all_literals?, #array?, #block?, #call?, #camelize, #class_name, #constant?, #contains_class?, #cookies?, #dir_glob?, #false?, #hash?, #hash_access, #hash_insert, #hash_iterate, #hash_values, #integer?, #kwsplat?, #literal?, #make_call, #node_type?, #number?, #params?, #pluralize, #rails_version, #recurse_check?, #regexp?, #remove_kwsplat, #request_headers?, #request_value?, #result?, #safe_literal, #safe_literal?, #safe_literal_target?, #set_env_defaults, #sexp?, #simple_literal?, #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 



60
61
62
63
64
65
66
67
68
 
# 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



28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
 
# 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



17
18
19
20
21
22
23
24
25
 
# 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