CVE-2018-16285 in UserPro Plugin
Summary
by MITRE
The UserPro plugin through 4.9.23 for WordPress allows XSS via the shortcode parameter in a userpro_shortcode_template action to wp-admin/admin-ajax.php.
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Analysis
by VulDB Data Team • 03/21/2020
The vulnerability CVE-2018-16285 represents a cross-site scripting flaw in the UserPro plugin for WordPress, affecting versions through 4.9.23. This security issue stems from inadequate input validation and output escaping mechanisms within the plugin's handling of shortcode parameters. The vulnerability specifically manifests when the plugin processes the shortcode parameter through the userpro_shortcode_template action endpoint located at wp-admin/admin-ajax.php, creating an avenue for malicious actors to inject and execute arbitrary script code within the context of a victim's browser session.
The technical exploitation of this vulnerability occurs through the manipulation of the shortcode parameter in the userpro_shortcode_template action, which is designed to handle AJAX requests within the WordPress admin interface. When the plugin fails to properly sanitize or escape user-supplied input before rendering it in the response, attackers can craft malicious payloads that get executed when legitimate users view pages containing the vulnerable shortcode. This type of vulnerability falls under CWE-79 which categorizes cross-site scripting flaws as weaknesses in input validation and output encoding. The attack vector is particularly concerning because it leverages the admin-ajax.php endpoint, which typically requires authentication but can be exploited if an attacker can manipulate parameters through a legitimate user session or if the plugin's access controls are bypassed.
The operational impact of this vulnerability extends beyond simple script execution as it can lead to complete session hijacking, privilege escalation, and potential full system compromise. Attackers can leverage the XSS vulnerability to steal cookies, modify user permissions, inject malicious content into the admin interface, or redirect users to phishing sites. The vulnerability affects the integrity of the WordPress admin environment and can compromise the trust model between the administrator and the system. According to ATT&CK framework, this represents a technique categorized under T1059.007 for command and scripting interpreter, specifically targeting the execution of malicious scripts through web interfaces. The vulnerability particularly affects WordPress installations where UserPro plugin is active, potentially compromising thousands of sites depending on the plugin's adoption rate.
Mitigation strategies for CVE-2018-16285 should prioritize immediate plugin updates to version 4.9.24 or later, which contains the necessary patches to address the input validation issues. Administrators should also implement proper input sanitization measures at the web application firewall level, particularly focusing on the wp-admin/admin-ajax.php endpoint and its parameter handling. The implementation of Content Security Policy headers can provide additional protection against script injection attempts by restricting the sources from which scripts can be loaded. Regular security audits of WordPress plugins should be conducted to identify and remediate similar vulnerabilities, with particular attention to plugins that handle AJAX requests and user-generated content. Network monitoring should be enhanced to detect suspicious parameter patterns that might indicate exploitation attempts, and user access controls should be reviewed to ensure that only authorized personnel have administrative privileges that could be compromised through such vulnerabilities.