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::PARAMETERS, Util::PARAMS_SEXP, Util::PATH_PARAMETERS, Util::QUERY_PARAMETERS, Util::REQUEST_COOKIES, Util::REQUEST_ENV, Util::REQUEST_PARAMETERS, Util::REQUEST_PARAMS, 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_call, #process_cookies, #process_default, #process_dstr, #process_if, #process_params

Methods included from Util

#array?, #block?, #call?, #camelize, #class_name, #constant?, #contains_class?, #context_for, #cookies?, #false?, #file_by_name, #file_for, #github_url, #hash?, #hash_access, #hash_insert, #hash_iterate, #integer?, #make_call, #node_type?, #number?, #params?, #pluralize, #rails_version, #regexp?, #relative_path, #request_env?, #request_value?, #result?, #set_env_defaults, #sexp?, #string?, #string_interp?, #symbol?, #table_to_csv, #template_path_to_name, #true?, #truncate_table, #underscore

Methods included from ProcessorHelper

#current_file_name, #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 



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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

    message = "Symbol conversion from unsafe string (#{friendly_type_of input})"

    warn :result => result,
      :warning_type => "Denial of Service",
      :warning_code => :unsafe_symbol_creation,
      :message => message,
      :user_input => input,
      :confidence => confidence
  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 >= "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 50

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