presidentbeef/brakeman

require 'brakeman/checks/base_check'

class Brakeman::CheckSimpleFormat < Brakeman::CheckCrossSiteScripting
  Brakeman::Checks.add self

  @description = "Checks for simple_format XSS vulnerability (CVE-2013-6416) in certain versions"

  def initialize *args
    super
    @found_any = false
  end

  def run_check
    if version_between? "4.0.0", "4.0.1"
      @inspect_arguments = true
      @ignore_methods = Set[:h, :escapeHTML]

      check_simple_format_usage
      generic_warning unless @found_any
    end
  end

  def generic_warning
    message = msg(msg_version(rails_version), " has a vulnerability in ", msg_code("simple_format"), " ", msg_cve("CVE-2013-6416"), ". Upgrade to ", msg_version("4.0.2"))

    warn :warning_type => "Cross-Site Scripting",
      :warning_code => :CVE_2013_6416,
      :message => message,
      :confidence => :medium,
      :gem_info => gemfile_or_environment,
      :link_path => "https://groups.google.com/d/msg/ruby-security-ann/5ZI1-H5OoIM/ZNq4FoR2GnIJ",
      :cwe_id => [79]
  end

  def check_simple_format_usage
    tracker.find_call(:target => false, :method => :simple_format).each do |result|
      @matched = false
      process_call result[:call]
      if @matched
        warn_on_simple_format result, @matched
      end
    end
  end

  def process_call exp
    @mark = true
    actually_process_call exp
    exp
  end

  def warn_on_simple_format result, match
    return unless original? result

    @found_any = true

    warn :result => result,
      :warning_type => "Cross-Site Scripting",
      :warning_code => :CVE_2013_6416_call,
      :message => msg("Values passed to ", msg_code("simple_format"), " are not safe in ", msg_version(rails_version)),
      :confidence => :high,
      :link_path => "https://groups.google.com/d/msg/ruby-security-ann/5ZI1-H5OoIM/ZNq4FoR2GnIJ",
      :user_input => match,
      :cwe_id => [79]
  end
end