Class: Brakeman::CheckSymbolDoS

Inherits:
BaseCheck 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!]

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_call, #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

#check_unsafe_symbol_creation(result) ⇒ Object 



19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
 
# 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 



10
11
12
13
14
15
16
17
 
# 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) 


53
54
55
56
57
58
59
60
61
62
63
64
65
 
# 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) 


67
68
69
70
71
 
# 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