Class: Brakeman::CheckLinkTo

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

Overview

Checks for calls to link_to in versions of Ruby where link_to did not escape the first argument.

See rails.lighthouseapp.com/projects/8994/tickets/3518-link_to-doesnt-escape-its-input

Direct Known Subclasses

CheckLinkToHref

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_PARAMETERS, Util::COOKIES, Util::PARAMETERS, Util::PATH_PARAMETERS, Util::QUERY_PARAMETERS, Util::REQUEST_ENV, Util::REQUEST_PARAMETERS, Util::REQUEST_PARAMS, Util::SESSION

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

#check_for_immediate_xss, #process_cookies, #process_escaped_output, #process_format, #process_format_escaped, #process_if, #process_output, #process_params, #process_render, #process_string_interp, #raw_call?

Methods inherited from BaseCheck

#add_result, #initialize, #process_cookies, #process_default, #process_if, #process_params

Methods included from Util

#array?, #call?, #camelize, #contains_class?, #context_for, #cookies?, #false?, #file_by_name, #file_for, #hash?, #hash_access, #hash_insert, #hash_iterate, #integer?, #node_type?, #number?, #params?, #pluralize, #regexp?, #request_env?, #request_value?, #result?, #set_env_defaults, #sexp?, #string?, #symbol?, #table_to_csv, #true?, #truncate_table, #underscore

Methods included from ProcessorHelper

#class_name, #process_all, #process_module

Methods inherited from SexpProcessor

#error_handler, #in_context, #initialize, #process, #process_dummy, #scope

Constructor Details

This class inherits a constructor from Brakeman::BaseCheck

Instance Method Details

#actually_process_call(exp) ⇒ Object 



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# File 'lib/brakeman/checks/check_link_to.rb', line 130

def actually_process_call exp
  return if @matched

  target = exp.target
  if sexp? target
    target = process target.dup
  end

  #Bare records create links to the model resource,
  #not a string that could have injection
  if model_name? target and context == [:call, :arglist]
    return exp
  end

  super
end

#check_argument(result, exp) ⇒ Object 



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# File 'lib/brakeman/checks/check_link_to.rb', line 63

def check_argument result, exp
  arg = process exp

  if input = has_immediate_user_input?(arg)
    case input.type
    when :params
      message = "Unescaped parameter value in link_to"
    when :cookies
      message = "Unescaped cookie value in link_to"
    else
      message = "Unescaped user input value in link_to"
    end

    add_result result
    warn :result => result,
      :warning_type => "Cross Site Scripting", 
      :message => message,
      :user_input => input.match,
      :confidence => CONFIDENCE[:high],
      :link_path => "link_to"

  elsif not tracker.options[:ignore_model_output] and match = has_immediate_model?(arg)
    method = match[2]

    unless IGNORE_MODEL_METHODS.include? method
      add_result result

      if MODEL_METHODS.include? method or method.to_s =~ /^find_by/
        confidence = CONFIDENCE[:high]
      else
        confidence = CONFIDENCE[:med]
      end

      warn :result => result,
        :warning_type => "Cross Site Scripting", 
        :message => "Unescaped model attribute in link_to",
        :user_input => match,
        :confidence => confidence,
        :link_path => "link_to"
    end

  elsif @matched
    if @matched.type == :model and not tracker.options[:ignore_model_output]
      message = "Unescaped model attribute in link_to"
    elsif @matched.type == :params
      message = "Unescaped parameter value in link_to"
    end

    if message
      add_result result

      warn :result => result, 
        :warning_type => "Cross Site Scripting", 
        :message => message,
        :user_input => @matched.match,
        :confidence => CONFIDENCE[:med],
        :link_path => "link_to"
    end
  end
end

#process_call(exp) ⇒ Object 



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# File 'lib/brakeman/checks/check_link_to.rb', line 124

def process_call exp
  @mark = true
  actually_process_call exp
  exp
end

#process_result(result) ⇒ Object 



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# File 'lib/brakeman/checks/check_link_to.rb', line 36

def process_result result
  return if duplicate? result

  #Have to make a copy of this, otherwise it will be changed to
  #an ignored method call by the code above.
  call = result[:call] = result[:call].dup

  args = call.args

  @matched = false

  #Skip if no arguments(?) or first argument is a hash
  return if args.first.nil? or hash? args.first

  if version_between? "2.0.0", "2.2.99"
    check_argument result, args.first

    if args.second and not hash? args.second
      check_argument result, args.second
    end
  elsif args.second
    #Only check first argument if there is a second argument
    #in Rails 2.3.x
    check_argument result, args.first
  end
end

#run_check ⇒ Object 



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# File 'lib/brakeman/checks/check_link_to.rb', line 12

def run_check
  return unless version_between?("2.0.0", "2.9.9") and not tracker.config[:escape_html]

  @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, :url_for,
                         :will_paginate].merge tracker.options[:safe_methods]

  @known_dangerous = []
  #Ideally, I think this should also check to see if people are setting
  #:escape => false
  methods = tracker.find_call :target => false, :method => :link_to 

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

  methods.each do |call|
    process_result call
  end
end