DefenseCode ThunderScan SAST Advisory WordPress No External Links Plugin Security Vulnerability Advisory ID: DC-2017-01-022 Advisory Title: WordPress No External Links Plugin Security Vulnerability Advisory URL: http://www.defensecode.com/advisories.php Software: WordPress No External Links Plugin Language: PHP Version: 3.5.17 and below Vendor Status: Vendor contacted, update released Release Date: 2017/05/29 Risk: Medium 1. General Overview =================== During the security audit of No External Links 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, this plugin has many cool features a outgoing clicks stats, fulllink masking, custom redirects, masking links to digital short code and base64 encoding and so on. It is designed for specialists who sell different kind of advertisment on their web site (for example, with sape system) and care about the number of outgoing links that can be found by search engines. It has more than 20,000 downloads on wordpress.org. Homepage: https://wordpress.org/plugins/wp-noexternallinks/ http://jehy.ru/articles/2008/10/05/wordpress-plugin-no-external-links/ 3. Vulnerability Description ================================== During the security analysis, ThunderScan discovered Cross-Site Scripting vulnerability in No External Links 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. 3.1. Cross-Site Scripting Function: echo Variable: $_REQUEST['date1'], $_REQUEST['date2'] Sample URL: http://vulnerablesite.com/wp-admin/options-general.php?page=wp-noexternallinks%2Fwp-noexternallinks-options.php&action=stats&date1="><script>alert(1)</script> Sample URL: http://vulnerablesite.com/wp-admin/options-general.php?page=wp-noexternallinks%2Fwp-noexternallinks-options.php&action=stats&date2="><script>alert(1)</script> File: wp-noexternallinks\wp-noexternallinks-options.php --------- 125 $date1 = $_REQUEST['date1']; ... 129 $date2 = $_REQUEST['date2']; ... 134 <input type="text" name="date1" value="<?php echo $date1; ?>"> <?php _e('to', 'wp-noexternallinks'); ?> 135 <input type="text" name="date2" value="<?php echo $date2; ?>"><input type="submit" --------- 4. Solution =========== Vendor resolved the security issues after we reported the vulnerability. All users are strongly advised to update WordPress No External Links plugin to the latest available version. 5. Credits ========== Discovered with DefenseCode ThunderScan source code security analyzer by Neven Biruski. 6. Disclosure Timeline ====================== 2017/04/06 Vendor contacted 2017/04/13 Vendor responded, update released 2017/05/29 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/