WordPress Booking Calendar 7.0 / 7.1 SQL Injection / Local File Inclusion

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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: http://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:  
http://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/  
http://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  
http://www.defensecode.com/ .  
  
E-mail: defensecode[at]defensecode.com  
  
Website: http://www.defensecode.com  
Twitter: https://twitter.com/DefenseCode/  
  
  
  
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