Add check for CVE-2012-3464 (single quotes)

lib/brakeman/checks/check_single_quotes.rb

+require 'brakeman/checks/base_check'
+
+#Checks for versions which do not escape single quotes.
+#https://groups.google.com/d/topic/rubyonrails-security/kKGNeMrnmiY/discussion
+class Brakeman::CheckSingleQuotes < Brakeman::BaseCheck
+  Brakeman::Checks.add self
+  RACK_UTILS = Sexp.new(:colon2, Sexp.new(:const, :Rack), :Utils)
+
+  @description = "Check for versions which do not escape single quotes (CVE-2012-3464)"
+
+  def initialize *args
+    super
+    @inside_erb = @inside_util = @inside_html_escape = @uses_rack_escape = false
+  end
+
+  def run_check
+    return if uses_rack_escape?
+
+    case
+    when version_between?('2.0.0', '2.3.14')
+      message = "All Rails 2.x versions do not escape single quotes (CVE-2012-3464)"
+    when version_between?('3.0.0', '3.0.16')
+      message = "Rails #{tracker.config[:rails_version]} does not escape single quotes (CVE-2012-3464). Upgrade to 3.0.17"
+    when version_between?('3.1.0', '3.1.7')
+      message = "Rails #{tracker.config[:rails_version]} does not escape single quotes (CVE-2012-3464). Upgrade to 3.1.8"
+    when version_between?('3.2.0', '3.2.7')
+      message = "Rails #{tracker.config[:rails_version]} does not escape single quotes (CVE-2012-3464). Upgrade to 3.2.8"
+    else
+      return
+    end
+
+    warn :warning_type => "Cross Site Scripting",
+      :message => message,
+      :confidence => CONFIDENCE[:med],
+      :file => gemfile_or_environment,
+      :link_path => "https://groups.google.com/d/topic/rubyonrails-security/kKGNeMrnmiY/discussion"
+  end
+
+  #Process initializers to see if they use workaround
+  #by replacing Erb::Util.html_escape
+  def uses_rack_escape?
+    @tracker.initializers.each do |name, src|
+      process src
+    end
+
+    @uses_rack_escape
+  end
+
+  #Look for
+  #
+  #    class ERB
+  def process_class exp
+    if exp[1] == :ERB
+      @inside_erb = true
+      process exp[-1]
+      @inside_erb = false
+    end
+
+    exp
+  end
+
+  #Look for
+  #
+  #    module Util
+  def process_module exp
+    if @inside_erb and exp[1] == :Util
+      @inside_util = true
+      process exp[-1]
+      @inside_util = false
+    end
+
+    exp
+  end
+
+  #Look for
+  #
+  #    def html_escape
+  def process_defn exp
+    if @inside_util and exp[1] == :html_escape
+      @inside_html_escape = true
+      process exp[-1]
+      @inside_html_escape = false
+    end
+
+    exp
+  end
+
+  #Look for
+  #
+  #    Rack::Utils.escape_html
+  def process_call exp
+    if @inside_html_escape and exp[1] == RACK_UTILS and exp[2] == :escape_html
+      @uses_rack_escape = true
+    else
+      process exp[1] if exp[1]
+    end
+
+    exp
+  end
+end