Class: Brakeman::CheckRender

Inherits:
BaseCheck show all
Defined in:
lib/brakeman/checks/check_render.rb

Overview

Check calls to render() for dangerous values

Constant Summary

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_for_dynamic_path(result) ⇒ Object

Check if path to action or file is determined dynamically



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# File 'lib/brakeman/checks/check_render.rb', line 32

def check_for_dynamic_path result
  view = result[:call][2]

  if sexp? view and original? result
    return if renderable?(view)

    if input = has_immediate_user_input?(view)
      if string_interp? view
        confidence = :medium
      else
        confidence = :high
      end
    elsif input = include_user_input?(view)
      confidence = :weak
    else
      return
    end

    return if input.type == :model #skip models
    return if safe_param? input.match

    message = msg("Render path contains ", msg_input(input))

    warn :result => result,
      :warning_type => "Dynamic Render Path",
      :warning_code => :dynamic_render_path,
      :message => message,
      :user_input => input,
      :confidence => confidence,
      :cwe_id => [22]
  end
end

#check_for_rce(result) ⇒ Object 



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# File 'lib/brakeman/checks/check_render.rb', line 65

def check_for_rce result
  return unless version_between? "0.0.0", "3.2.22" or
                version_between? "4.0.0", "4.1.14" or
                version_between? "4.2.0", "4.2.5"


  view = result[:call][2]
  if sexp? view and not duplicate? result
    if params? view
      add_result result
      return if safe_param? view

      warn :result => result,
        :warning_type => "Remote Code Execution",
        :warning_code => :dynamic_render_path_rce,
        :message => msg("Passing query parameters to ", msg_code("render"), " is vulnerable in ", msg_version(rails_version), " ", msg_cve("CVE-2016-0752")),
        :user_input => view,
        :confidence => :high,
        :cwe_id => [22]
    end
  end
end

#known_renderable_class?(class_name) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/brakeman/checks/check_render.rb', line 108

def known_renderable_class? class_name
  klass = tracker.find_class(class_name)
  return false if klass.nil?
  knowns = [
    :"ViewComponent::Base",
    :"ViewComponentContrib::Base",
    :"Phlex::HTML"
  ]
  knowns.any? { |k| klass.ancestor? k }
end

#process_render_result(result) ⇒ Object 



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# File 'lib/brakeman/checks/check_render.rb', line 15

def process_render_result result
  return unless node_type? result[:call], :render

  case result[:call].render_type
  when :partial, :template, :action, :file
    check_for_rce(result) or
      check_for_dynamic_path(result)
  when :inline
  when :js
  when :json
  when :text
  when :update
  when :xml
  end
end

#renderable?(exp) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/brakeman/checks/check_render.rb', line 101

def renderable? exp
  return false unless call?(exp) and constant?(exp.target)

  target_class_name = class_name(exp.target)
  known_renderable_class?(target_class_name) or tracker.find_method(:render_in, target_class_name)
end

#run_check ⇒ Object 



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# File 'lib/brakeman/checks/check_render.rb', line 9

def run_check
  tracker.find_call(:target => nil, :method => :render).each do |result|
    process_render_result result
  end
end

#safe_param?(exp) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/brakeman/checks/check_render.rb', line 88

def safe_param? exp
  if params? exp and call? exp
    method_name = exp.method

    if method_name == :[]
      arg = exp.first_arg
      symbol? arg and [:controller, :action].include? arg.value
    else
      boolean_method? method_name
    end
  end
end