Drupal SuperCron 6.x-1.3 XSS Vulnerability

[Justin Klein Keane <justin () madirish net>]

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Description of Vulnerability:
- -----------------------------
Drupal (http://drupal.org) is a robust content management system (CMS)
written in PHP and MySQL.  The Drupal SuperCron module
(https://drupal.org/project/supercron), created by 63 Reasons
(http://www.63reasons.com/), "is a complete replacement for Drupal's
built-in Cron functionality."  The SuperCron module contains a
persistent arbitrary HTML injection vulnerability (also known as cross
site scripting, or XSS) due to the fact that it fails to user supplied
third party data before display.

Systems affected:
- -----------------
Drupal 6.22 with SuperCron 6.x-1.3 was tested and shown to be vulnerable

Impact
- ------
Attackers could inject arbitrary scripts into pages affecting site
users.  This could result in administrative account compromise leading
to web server process compromise.  A more likely scenario would be for
an attacker to inject hidden content (such as iframes, applets, or
embedded objects) that would attack client browsers in an attempt to
compromise site users' machines.  This vulnerability could also be
used to launch cross site request forgery (XSRF) attacks against the
site that could have other unexpected consequences.

Mitigating factors:
- -------------------
In order to exploit this vulnerability the attacker must have
permissions to access administration pages.  This is an extremely
loose permission given the impact not only of this vulnerability but
also of the module's general functionality.

Proof of concept:
- -----------------
1.  Install Drupal 6-22 and install and enable SuperCron 6.x-1.3
2.  Navigate to SuperCron's Firewall settings at
?q=admin/settings/supercron/firewall
3.  Enable the firewall
4.  Expand the 'Insert IP' portion of the form
5.  Insert "<script>alert('xss');</script>" for the IP address and
click the "Insert" button
6.  Observe the transient JavaScript in the Drupal confirmation message
7.  Persistent JavaScript is rendered at
?q=admin/settings/supercron/firewall

Patch:
- ------------------------------------------
Applying the following patch mitigates this issue in version 6.x-1.3
(and adds new permissions for the module)

- --- supercron/supercron.module        2009-06-15 02:55:20.000000000 -0400
+++ supercron.fixed/supercron.module    2011-10-30 00:34:24.316054217 -0400
@@ -23,7 +23,7 @@ function supercron_menu() {
     'description' => t('Configure how Cron behaves, which cron hooks
are called and in what order, capture debugging information and
parallelize tasks.'),
     'page callback' => 'drupal_get_form',
     'page arguments' => array('supercron_settings'),
- -    'access arguments' => array('access administration pages'),
+    'access arguments' => array('administer SuperCron'),
     );
   $items['admin/settings/supercron/'] = array(
     'title' => t('Settings'),
@@ -34,20 +34,20 @@ function supercron_menu() {
     'title' => t('Firewall'),
     'page callback' => 'drupal_get_form',
     'page arguments' => array('supercron_firewall_form'),
- -    'access arguments' => array('access administration pages'),
+    'access arguments' => array('administer SuperCron'),
     'type' => MENU_LOCAL_TASK,
     'parent' => 'admin/settings/supercron'
     );
   $items['admin/settings/supercron/firewall/delete'] = array(
     'page callback' => 'supercron_firewall_delete',
- -    'access arguments' => array('access administration pages'),
+    'access arguments' => array('administer SuperCron'),
     'type' => MENU_CALLBACK
     );
   $items['admin/settings/supercron/output/%'] = array(
     'title' => t('Cron output in module: '),
     'page callback' => 'supercron_output',
     'page arguments' => array(4),
- -    'access arguments' => array('access administration pages'),
+    'access arguments' => array('administer SuperCron'),
     'type' => MENU_CALLBACK,
     );

@@ -55,7 +55,7 @@ function supercron_menu() {
     'title' => t('Cron exceptions in module: '),
     'page callback' => 'supercron_exception',
     'page arguments' => array(4),
- -    'access arguments' => array('access administration pages'),
+    'access arguments' => array('administer SuperCron'),
     'type' => MENU_CALLBACK,
     );

@@ -63,20 +63,20 @@ function supercron_menu() {
     'title' => t('Call individual cron handlers'),
     'page callback' => 'supercron_invoke_one',
     'page arguments' => array(4, 5),
- -    'access arguments' => array('access administration pages'),
+    'access arguments' => array('administer SuperCron'),
     'type' => MENU_CALLBACK,
     );

   $items[SUPERCRON_INVOKE_ALL] = array(
     'page callback' => 'supercron_drupal_cron_run',
- -    'access arguments' => array('access administration pages'),
+    'access arguments' => array('administer SuperCron'),
     'type' => MENU_CALLBACK,
     'file' => 'cron.inc',
     );

   $items['admin/reports/status/run-cron'] = array(
     'page callback' => 'supercron_drupal_cron_run',
- -    'access arguments' => array('access administration pages'),
+    'access arguments' => array('administer SuperCron'),
     'type' => MENU_CALLBACK,
     'file' => 'cron.inc',
     );
@@ -137,6 +137,12 @@ function supercron_firewall_delete($id)
   drupal_goto('admin/settings/supercron/firewall');
 }

+function supercron_firewall_form_validate($form, &$form_state) {
+       if (! preg_match('/\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}/',
$form_state['values']['ip']) > 0) {
+               form_set_error('', t('Invalid IP address.'));
+       }
+}
+
 function supercron_firewall_form(&$form_state) {
   $firewall_enabled =
variable_get(SUPERCRON_FIREWALL_ENABLED_VARIABLE, FALSE);
   $form['firewall_enable_field'] = array(
@@ -206,11 +212,11 @@ function supercron_firewall_form(&$form_
     $result = db_query('SELECT * FROM {supercron_ips}');
     while ($ip = db_fetch_object($result)) {
       if ($firewall_enabled) {
- -        $form[$ip->iid]['title'] = array('#value' => $ip->ip);
+        $form[$ip->iid]['title'] = array('#value' =>
check_plain($ip->ip));
         $form[$ip->iid]['delete'] = array('#value' => l(t('delete'),
"admin/settings/supercron/firewall/delete/" . $ip->iid));
       }
       else {
- -        $form[$ip->iid]['title'] = array('#value' => $ip->ip);
+        $form[$ip->iid]['title'] = array('#value' =>
check_plain($ip->ip));
         $form[$ip->iid]['delete'] = array('#value' => '<span
style="text-decoration: line-through;">' . t('delete') . '</span>');
       }
     }
@@ -220,8 +226,10 @@ function supercron_firewall_form(&$form_
 }

 function supercron_firewall_add() {
- -  db_query("INSERT INTO {supercron_ips} (ip) VALUES ('%s')",
$_POST['ip']);
- -  drupal_set_message("IP $_POST[ip] added.");
+       if (preg_match('/\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}/', $_POST['ip'])
> 0) {
+         db_query("INSERT INTO {supercron_ips} (ip) VALUES ('%s')",
$_POST['ip']);
+         drupal_set_message("IP $_POST[ip] added.");
+       }
 }

 function supercron_firewall_enable() {
@@ -457,7 +465,7 @@ function supercron_module_add_output($mo
 function supercron_output($id) {
   $module = db_fetch_array(db_query_range("SELECT * FROM
{supercron_enabled_mods} WHERE id=%d", (int)$id, 0, 1));
   drupal_set_title(drupal_get_title() . $module["module_name"]);
- -  $output = $module["output"];
+  $output = filter_admin_xss($module["output"]);
   return $output;
 }


- -- 
Justin Klein Keane
http://www.MadIrish.net

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