DefenseCode ThunderScan SAST Advisory: WordPress Booking Calendar
             Multiple Security Vulnerabilities


Advisory ID:    DC-2017-12-005
Advisory Title: WordPress Booking Calendar Plugin Multiple Vulnerabilities
Advisory URL:   https://www.defensecode.com/advisories.php
Software:       WordPress Booking Calendar plugin
Language:       PHP
Version:        7.0/7.1 and below
Vendor Status:  Vendor contacted, updates released
Release Date:   2017/12/13
Risk:           Medium



1. General Overview
===================
During the security audit of Booking Calendar plugin for WordPress
CMS, multiple vulnerabilities were discovered using DefenseCode
ThunderScan application source code security analysis platform.

More information about ThunderScan is available at URL:
https://www.defensecode.com


2. Software Overview
====================
Booking Calendar plugin - described by the authors as the ultimate
booking system for online reservation and availability checking
service for your site.

According to wordpress.org, it has more than 40,000 active installs.

Homepage:
https://wordpress.org/plugins/booking/
https://wpbookingcalendar.com/
https://wordpress.org/plugins/booking/#developers


3. Vulnerability Description
============================
During the security analysis, ThunderScan discovered SQL injection and
Local file inclusion vulnerabilities in Booking Calendar WordPress
plugin.

The easiest way to reproduce the SQL injection vulnerabilities is to
send the specified parameter to the provided URL while being logged in
as administrator or another user that is authorized to access the
plugin settings page. Users that do not have full administrative
privileges could abuse the database access the vulnerabilities provide
to either escalate their privileges or obtain and modify database
contents they were not supposed to be able to.

By requesting a specially crafted URL, the attacker can cause remote
server to execute a php file of his choosing. Although the user
requesting the URL has to be logged into the WordPress administrative
console, the attacker can cause the administrator to request such a
URL by using various social engineering/phishing approaches. Specified
file will be interpreted by php interpreter, and any valid php code
will indeed be executed. If the php installation on server has
"allow_url_include=1" configuration option set, this attack can be
expanded to execute a php file from any remote URL. If the php version
is less than 5.3.4, the ".php" that gets appended to the end of the
file name attacker chose can be omitted by adding a null character
("%00") to the requested URL, and enable the attacker to execute any
file, regardless of the extension.

Due to the CSRF token needed to perform the attack the risk is lowered
to medium.

3.1. SQL injection
  Function: $wpdb->query()
  Variable: $_POST[ "booking_id" ];
  Vulnerable URL: /wp-admin/admin-ajax.php
  File: booking\lib\wpbc-ajax.php
        ---------
        152    $booking_id         = $_POST[ "booking_id" ];
    153    $approved_id        = explode('|',$booking_id);
        ...
        162    $approved_id_str = join( ',', $approved_id);
        ...
        165    if ( false === $wpdb->query( $wpdb->prepare( "UPDATE
{$wpdb->prefix}bookingdates SET approved = %s WHERE booking_id IN
({$approved_id_str})", $is_approve_or_pending ) ) ){     
        ---------
       
3.2. SQL injection
  Function: $wpdb->query()
  Variable: $_POST[ "booking_id" ];
  Vulnerable URL: /wp-admin/admin-ajax.php
  Vulnerable code snippets:
  File: booking\lib\wpbc-ajax.php
        ---------
        110    $id_of_new_bookings  = $_POST[ "booking_id" ];
        111    $arrayof_bookings_id = explode('|',$id_of_new_bookings);
        ...
        114    wpbc_update_number_new_bookings( $arrayof_bookings_id,
$is_new , $user_id );
        ---------
  File: booking\lib\wpdev-booking-functions.php
        ---------
        1468 function wpbc_update_number_new_bookings(
$id_of_new_bookings, $is_new = '0' , $user_id = 1 ){
        ...
        1485   $update_sql = "UPDATE {$wpdb->prefix}booking AS bk SET
bk.is_new = {$is_new} WHERE bk.booking_id IN  ( {$id_of_new_bookings} ) ";
        ...
        1487   if ( false === $wpdb->query( $update_sql  ) ) {
        ---------

3.3 PHP file inclusion
  Function: include()
  Variable: $_POST['captcha_chalange']
  Vulnerable URL: /wp-admin/admin-ajax.php
  Vulnerable code snippets:
  File: booking\core\lib\wpbc-booking-new.php
        ---------
        127    if (! wpbc_check_CAPTCHA( $_POST['captcha_user_input'],
$_POST['captcha_chalange'], $bktype ) ) {
        ...
        19   function wpbc_check_CAPTCHA( $the_answer_from_respondent,
$prefix, $bktype ) {
        ...
        23       $correct = $captcha_instance->check($prefix,
$the_answer_from_respondent);
        ---------
  File: wp-content\plugins\booking\js\captcha\captcha.php
        ---------
        139  function check( $prefix, $response ) {
        ...
        141    include( $this->tmp_dir . $prefix . '.php' );
        ---------
 

4. Solution
===========
Vendor resolved the security issues. All users are strongly advised to
update WordPress Booking Calendar plugin to the latest available
version.


5. Credits
==========
Discovered by Neven Biruski using DefenseCode ThunderScan source code
security analyzer.

 
6. Disclosure Timeline
======================
2016/11/15   Vulnerabilities discovered
2017/04/04   Vendor contacted
2017/04/04   Vendor responded - 7.0 already fixed SQL injection vulns
2017/04/04   Update released for LFI (7.1)
2017/12/13   Advisory released to the public


7. About DefenseCode
====================
DefenseCode L.L.C. delivers products and services designed to analyze
and test web, desktop and mobile applications for security
vulnerabilities.

DefenseCode ThunderScan is a SAST (Static Application Security
Testing, WhiteBox Testing) solution for performing extensive security
audits of application source code. ThunderScan SAST performs fast and
accurate analyses of large and complex source code projects delivering
precise results and low false positive rate.

DefenseCode WebScanner is a DAST (Dynamic Application Security
Testing, BlackBox Testing) solution for comprehensive security audits
of active web applications. WebScanner will test a website's security
by carrying out a large number of attacks using the most advanced
techniques, just as a real attacker would.

Subscribe for free software trial on our website
https://www.defensecode.com/ .

E-mail: defensecode[at]defensecode.com

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