Class: Brakeman::CheckContentTag

Inherits:
CheckCrossSiteScripting show all
Defined in:
lib/brakeman/checks/check_content_tag.rb

Overview

Checks for unescaped values in ‘content_tag`

content_tag :tag, body
                   ^-- Unescaped in Rails 2.x

content_tag, :tag, body, attribute => value
                            ^-- Unescaped in all versions

content_tag, :tag, body, attribute => value
                                        ^
                                        |
        Escaped by default, can be explicitly escaped
        or not by passing in (true|false) as fourth argument

Constant Summary

Constants inherited from CheckCrossSiteScripting

Brakeman::CheckCrossSiteScripting::CGI, Brakeman::CheckCrossSiteScripting::FORM_BUILDER, Brakeman::CheckCrossSiteScripting::HAML_HELPERS, Brakeman::CheckCrossSiteScripting::IGNORE_LIKE, Brakeman::CheckCrossSiteScripting::IGNORE_MODEL_METHODS, Brakeman::CheckCrossSiteScripting::MODEL_METHODS, Brakeman::CheckCrossSiteScripting::URI, Brakeman::CheckCrossSiteScripting::XML_HELPER

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 CheckCrossSiteScripting

#actually_process_call, #cgi_escaped?, #check_for_immediate_xss, #form_builder_method?, #haml_escaped?, #html_safe_call?, #ignore_call?, #ignored_method?, #ignored_model_method?, #initialize, #likely_model_attribute?, #process_case, #process_cookies, #process_dstr, #process_escaped_output, #process_format, #process_format_escaped, #process_if, #process_output, #process_params, #process_render, #raw_call?, #safe_input_attribute?, #setup, #xml_escaped?

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::CheckCrossSiteScripting

Instance Method Details

#check_argument(result, exp) ⇒ Object 



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# File 'lib/brakeman/checks/check_content_tag.rb', line 104

def check_argument result, exp
  #Check contents of raw() calls directly
  if raw? exp
    arg = process exp.first_arg
  else
    arg = process exp
  end

  if input = has_immediate_user_input?(arg)
    message = msg("Unescaped ", msg_input(input), " in ", msg_code("content_tag"))

    add_result result

    warn :result => result,
      :warning_type => "Cross-Site Scripting",
      :warning_code => :xss_content_tag,
      :message => message,
      :user_input => input,
      :confidence => :high,
      :link_path => "content_tag",
      :cwe_id => [79]

  elsif not tracker.options[:ignore_model_output] and match = has_immediate_model?(arg)
    unless IGNORE_MODEL_METHODS.include? match.method
      add_result result

      if likely_model_attribute? match
        confidence = :high
      else
        confidence = :medium
      end

      warn :result => result,
        :warning_type => "Cross-Site Scripting",
        :warning_code => :xss_content_tag,
        :message => msg("Unescaped model attribute in ", msg_code("content_tag")),
        :user_input => match,
        :confidence => confidence,
        :link_path => "content_tag",
        :cwe_id => [79]
    end

  elsif @matched
    return if @matched.type == :model and tracker.options[:ignore_model_output]

    message = msg("Unescaped ", msg_input(@matched), " in ", msg_code("content_tag"))

    add_result result

    warn :result => result,
      :warning_type => "Cross-Site Scripting",
      :warning_code => :xss_content_tag,
      :message => message,
      :user_input => @matched,
      :confidence => :medium,
      :link_path => "content_tag",
      :cwe_id => [79]
  end
end

#check_cve_2016_6316 ⇒ Object 



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# File 'lib/brakeman/checks/check_content_tag.rb', line 176

def check_cve_2016_6316
  if cve_2016_6316?
    confidence = if @content_tags.any?
                   :high
                 else
                   :medium
                 end

    fix_version = case
                  when version_between?("3.0.0", "3.2.22.3")
                    "3.2.22.4"
                  when version_between?("4.0.0", "4.2.7.0")
                    "4.2.7.1"
                  when version_between?("5.0.0", "5.0.0")
                    "5.0.0.1"
                  when (version.nil? and tracker.options[:rails3])
                    "3.2.22.4"
                  when (version.nil? and tracker.options[:rails4])
                    "4.2.7.2"
                  else
                    return
                  end

    warn :warning_type => "Cross-Site Scripting",
      :warning_code => :CVE_2016_6316,
      :message => msg(msg_version(rails_version), " ", msg_code("content_tag"), " does not escape double quotes in attribute values ", msg_cve("CVE-2016-6316"), ". Upgrade to ", msg_version(fix_version)),
      :confidence => confidence,
      :gem_info => gemfile_or_environment,
      :link_path => "https://groups.google.com/d/msg/ruby-security-ann/8B2iV2tPRSE/JkjCJkSoCgAJ",
      :cwe_id => [79]
  end
end

#cve_2016_6316? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/brakeman/checks/check_content_tag.rb', line 213

def cve_2016_6316?
  version_between? "3.0.0", "3.2.22.3" or
  version_between? "4.0.0", "4.2.7.0" or
  version_between? "5.0.0", "5.0.0.0"
end

#process_call(exp) ⇒ Object 



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# File 'lib/brakeman/checks/check_content_tag.rb', line 164

def process_call exp
  if @mark
    actually_process_call exp
  else
    @mark = true
    actually_process_call exp
    @mark = false
  end

  exp
end

#process_result(result) ⇒ Object 



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# File 'lib/brakeman/checks/check_content_tag.rb', line 45

def process_result result
  return if duplicate? result

  case result[:location][:type]
  when :template
    @current_template = result[:location][:template]
  when :class
    @current_class = result[:location][:class]
    @current_method = result[:location][:method]
  end

  @current_file = result[:location][:file]

  call = result[:call]
  args = call.arglist

  tag_name = args[1]
  content = args[2]
  attributes = args[3]
  escape_attr = args[4]

  @matched = false

  #Silly, but still dangerous if someone uses user input in the tag type
  check_argument result, tag_name

  #Versions before 3.x do not escape body of tag, nor does the rails_xss gem
  unless @matched or (tracker.options[:rails3] and not raw? content)
    check_argument result, content
  end

  # This changed in Rails 6.1.6
  if version_between? '0.0.0', '6.1.5' 
    #Attribute keys are never escaped, so check them for user input
    if not @matched and hash? attributes and not request_value? attributes
      hash_iterate(attributes) do |k, _v|
        check_argument result, k
        return if @matched
      end
    end
  end

  #By default, content_tag escapes attribute values passed in as a hash.
  #But this behavior can be disabled. So only check attributes hash
  #if they are explicitly not escaped.
  if not @matched and attributes and (false? escape_attr or cve_2016_6316?)
    if request_value? attributes or not hash? attributes
      check_argument result, attributes
    else #check hash values
      hash_iterate(attributes) do |_k, v|
        check_argument result, v
        return if @matched
      end
    end
  end
ensure
  @current_template = @current_class = @current_method = @current_file = nil
end

#raw?(exp) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/brakeman/checks/check_content_tag.rb', line 209

def raw? exp
  call? exp and exp.method == :raw
end

#run_check ⇒ Object 



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# File 'lib/brakeman/checks/check_content_tag.rb', line 21

def run_check
  @ignore_methods = Set[:button_to, :check_box, :escapeHTML, :escape_once,
                         :field_field, :fields_for, :h, :hidden_field,
                         :hidden_field, :hidden_field_tag, :image_tag, :label,
                         :mail_to, :radio_button, :select,
                         :submit_tag, :text_area, :text_field,
                         :text_field_tag, :url_encode, :u, :url_for,
                         :will_paginate].merge tracker.options[:safe_methods]

  @known_dangerous = []
  @content_tags = tracker.find_call :target => false, :method => :content_tag

  @models = tracker.models.keys
  @inspect_arguments = tracker.options[:check_arguments]
  @mark = nil

  Brakeman.debug "Checking for XSS in content_tag"
  @content_tags.each do |call|
    process_result call
  end

  check_cve_2016_6316
end