CVE-2021-21324 (published 2021-03-08T17:15Z)

GLPI is an open-source asset and IT management software package that provides ITIL Service Desk features, licenses tracking and software auditing. In GLPI before version 9.5.4 there is an Insecure Direct Object Reference (IDOR) on "Solutions". This vulnerability gives an unauthorized user the ability to enumerate GLPI items names (including users logins) using the knowbase search form (requires authentication). To Reproduce: Perform a valid authentication at your GLPI instance, Browse the ticket list and select any open ticket, click on Solution form, then Search a solution form that will redirect you to the endpoint /"glpi/front/knowbaseitem.php?item_itemtype=Ticket&item_items_id=18&forcetab=Knowbase$1", and the item_itemtype=Ticket parameter present in the previous URL will point to the PHP alias of glpi_tickets table, so just replace it with "Users" to point to glpi_users table instead; in the same way, item_items_id=18 will point to the related column id, so changing it too you should be able to enumerate all the content which has an alias. Since such id(s) are obviously incremental, a malicious party could exploit the vulnerability simply by guessing-based attempts.

Severity: MEDIUM
CVSS v2 base score: 4.0 (AV:N/AC:L/Au:S/C:P/I:N/A:N)
CVSS v3 base score: 6.5, MEDIUM (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N)

Weakness information:
cwe_id: CWE-639
cwe_name: Authorization Bypass Through User-Controlled Key
description: The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.
extended_description: 
            Retrieval of a user record occurs in the system based on some key value that is under user control. The key would typically identify a user-related record stored in the system and would be used to lookup that record for presentation to the user. It is likely that an attacker would have to be an authenticated user in the system. However, the authorization process would not properly check the data access operation to ensure that the authenticated user performing the operation has sufficient entitlements to perform the requested data access, hence bypassing any other authorization checks present in the system.
            For example, attackers can look at places where user specific data is retrieved (e.g. search screens) and determine whether the key for the item being looked up is controllable externally. The key may be a hidden field in the HTML form field, might be passed as a URL parameter or as an unencrypted cookie variable, then in each of these cases it will be possible to tamper with the key value.
            One manifestation of this weakness is when a system uses sequential or otherwise easily-guessable session IDs that would allow one user to easily switch to another user's session and read/modify their data.
         
         

Fix information:
repo_url: https://github.com/glpi-project/glpi
commit_details: repo_url: https://github.com/glpi-project/glpi
author: adelaunay
author_date: 2021-01-06 09:38:38+01:00
msg: validate entity_restrict when available with idor tokens
repository: repo_url: https://github.com/glpi-project/glpi
repo_name: glpi-project/glpi
description: GLPI is a Free Asset and IT Management Software package, Data center management, ITIL Service Desk, licenses tracking and software auditing.
repo_language: PHP
owner: glpi-project
file_changes: filename: dropdownTrackingDeviceType.php
change_type: ModificationType.MODIFY
diff: @@ -76,7 +76,9 @@ if ($isValidItemtype) {
       'multiple'            => $_POST["multiple"],
       'myname'              => $_POST["myname"],
       'rand'                => $_POST["rand"],
-      '_idor_token'         => Session::getNewIDORToken($itemtype),
+      '_idor_token'         => Session::getNewIDORToken($itemtype, [
+         'entity_restrict' => $_POST['entity_restrict'],
+      ]),
    ];
 
    if (isset($_POST["used"]) && !empty($_POST["used"])) {

programming_language: PHP
filename: computer_item.class.php
change_type: ModificationType.MODIFY
diff: @@ -682,7 +682,9 @@ class Computer_Item extends CommonDBRelation{
          'itemtype'        => $itemtype,
          'onlyglobal'      => $onlyglobal,
          'used'            => $used,
-         '_idor_token'     => Session::getNewIDORToken($itemtype),
+         '_idor_token'     => Session::getNewIDORToken($itemtype, [
+            'entity_restrict' => $entity_restrict,
+         ]),
       ];
 
       echo Html::jsAjaxDropdown($myname, $field_id,

programming_language: PHP
filename: dropdown.class.php
change_type: ModificationType.MODIFY
diff: @@ -173,11 +173,13 @@ class Dropdown {
             'condition'            => $params['condition'],
             'used'                 => $params['used'],
             'toadd'                => $params['toadd'],
-            'entity_restrict'      => (is_array($params['entity']) ? json_encode(array_values($params['entity'])) : $params['entity']),
+            'entity_restrict'      => ($entity_restrict = (is_array($params['entity']) ? json_encode(array_values($params['entity'])) : $params['entity'])),
             'on_change'            => $params['on_change'],
             'permit_select_parent' => $params['permit_select_parent'],
             'specific_tags'        => $params['specific_tags'],
-            '_idor_token'          => Session::getNewIDORToken($itemtype),
+            '_idor_token'          => Session::getNewIDORToken($itemtype, [
+               'entity_restrict' => $entity_restrict,
+            ]),
       ];
 
       $output = "<span class='no-wrap'>";
@@ -2182,6 +2184,11 @@ class Dropdown {
    public static function getDropdownValue($post, $json = true) {
       global $DB, $CFG_GLPI;
 
+      // check if asked itemtype is the one originaly requested by the form
+      if (!Session::validateIDOR($post)) {
+         return;
+      }
+
       if (isset($post["entity_restrict"])
          && !is_array($post["entity_restrict"])
          && (substr($post["entity_restrict"], 0, 1) === '[')
@@ -2199,11 +2206,6 @@ class Dropdown {
          $post['entity_restrict'] = $_SESSION['glpiactiveentities'];
       }
 
-      // check if asked itemtype is the one originaly requested by the form
-      if (!Session::validateIDOR($post)) {
-         return;
-      }
-
       // Security
       if (!($item = getItemForItemtype($post['itemtype']))) {
          return;

programming_language: PHP
filename: user.class.php
change_type: ModificationType.MODIFY
diff: @@ -4026,9 +4026,12 @@ JAVASCRIPT;
          'on_change'           => $p['on_change'],
          'used'                => $p['used'],
          'inactive_deleted'    => $p['inactive_deleted'],
-         'entity_restrict'     => (is_array($p['entity']) ? json_encode(array_values($p['entity'])) : $p['entity']),
+         'entity_restrict'     => ($entity_restrict = (is_array($p['entity']) ? json_encode(array_values($p['entity'])) : $p['entity'])),
          'specific_tags'       => $p['specific_tags'],
-         '_idor_token'         => Session::getNewIDORToken(__CLASS__, ['right' => $p['right']]),
+         '_idor_token'         => Session::getNewIDORToken(__CLASS__, [
+            'right'           => $p['right'],
+            'entity_restrict' => $entity_restrict,
+         ]),
       ];
 
       $output   = Html::jsAjaxDropdown($p['name'], $field_id,

programming_language: PHP
filename: Dropdown.php
change_type: ModificationType.MODIFY
diff: @@ -765,7 +765,7 @@ class Dropdown extends DbTestCase {
          }
       }
 
-      $params['_idor_token'] = \Session::getNewIDORToken($params['itemtype'] ?? '');
+      $params['_idor_token'] = $this->generateIdor($params);
 
       $result = \Dropdown::getDropdownValue($params, false);
 
@@ -928,7 +928,7 @@ class Dropdown extends DbTestCase {
          }
       }
 
-      $params['_idor_token'] = \Session::getNewIDORToken($params['itemtype'] ?? '');
+      $params['_idor_token'] = $this->generateIdor($params);
 
       $result = \Dropdown::getDropdownConnect($params, false);
 
@@ -1331,4 +1331,12 @@ class Dropdown extends DbTestCase {
             ->hasSize(2);
 
    }
+
+   private function generateIdor(array $params = []) {
+      $idor_add_params = [];
+      if (isset($params['entity_restrict'])) {
+         $idor_add_params['entity_restrict'] = $params['entity_restrict'];
+      }
+      return \Session::getNewIDORToken(($params['itemtype'] ?? ''), $idor_add_params);
+   }
 }

programming_language: PHP
filename: Session.php
change_type: ModificationType.MODIFY
diff: @@ -375,6 +375,7 @@ class Session extends \DbTestCase {
          ['itemtype' => 'Ticket'],
          ['itemtype' => 'Glpi\\Dashboard\\Item'],
          ['itemtype' => 'User', 'add_params' => ['right' => 'all']],
+         ['itemtype' => 'User', 'add_params' => ['entity_restrict' => 0]],
       ];
    }
 

programming_language: PHP