WordPress Gwolle Guestbook 2.5.3 Cross Site Scripting

`DefenseCode ThunderScan SAST Advisory: WordPress Gwolle Guestbook  
Plugin XSS Security Vulnerability  
  
  
Advisory ID: DC-2018-05-008  
Advisory Title: WordPress Gwolle Guestbook Plugin XSS Security  
Vulnerability  
Advisory URL: http://www.defensecode.com/advisories.php  
Software: WordPress Gwolle Guestbook plugin  
Language: PHP  
Version: 2.5.3 and below  
Vendor Status: Vendor contacted, update released  
Release Date: 2018/07/24  
Risk: Medium  
  
  
  
1. General Overview  
===================  
During the security audit of Gwolle Guestbook plugin for WordPress  
CMS, security vulnerability was 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  
====================  
According to the plugin developers, Gwolle Guestbook is is not just  
another guestbook for WordPress. The goal is to provide an easy and  
slim way to integrate a guestbook into your WordPress powered site.  
  
According to wordpress.org, it has more than 40,000 active installs.  
  
Homepage:  
https://wordpress.org/plugins/gwolle-gb/  
  
  
3. Vulnerability Description  
============================  
During the security analysis, ThunderScan discovered Cross-Site  
Scripting vulnerability in Gwolle Guestbook WordPress plugin.  
  
The Cross-Site Scripting vulnerability can enable the attacker to  
construct the URL that contains malicious JavaScript code. If the  
administrator of the site makes a request to such an URL, the  
attacker's code will be executed, with unrestricted access to the  
WordPress site in question. The attacker can entice the administrator  
to visit the URL in various ways, including sending the URL by email,  
posting it as a part of the comment on the vulnerable site or another  
forum.  
  
To confirm the vulnerability make sure dashboard widget is added and  
that there is at least one unchecked entry in the guestbook. The  
vulnerability was tested using Apache web server.  
  
3.1 Cross-Site Scripting  
Vulnerable Function: echo()  
Vulnerable Variable: $_SERVER['PHP_SELF']  
Vulnerable URL:  
http://vulnerablesite.com/wp-admin/index.php/"></script><script>alert(42)</script>  
  
File: gwolle-gb/admin/gb-dashboard-widget.php  
---------  
150 <a href="<?php echo $_SERVER['PHP_SELF']; ?>"  
class="button"><?php esc_html_e('Refresh', 'gwolle-gb'); ?></a>  
---------  
  
  
4. Solution  
===========  
All users are strongly advised to update WordPress Gwolle Guestbook  
plugin to the latest available version.  
  
  
5. Credits  
==========  
Discovered by Neven Biruski using DefenseCode ThunderScan source code  
security analyzer.  
  
  
6. Disclosure Timeline  
======================  
2018/06/01 Vulnerability discovered  
2018/06/05 Vendor contacted  
2018/07/24 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/  
  
`