Stored XSS in Ultimate Member WordPress Plugin

Executive Summary

This vulnerability exists in the Ultimate Member WordPress plugin, specifically in versions up to and including 2.11.4. It is a Stored Cross-Site Scripting (XSS) flaw that occurs via the 'about_me' parameter. The issue arises because the plugin does not properly sanitize input or escape output, allowing authenticated users with subscriber-level access or higher to inject malicious web scripts. These scripts then execute whenever any user views the affected page.

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Detection Guidance

This vulnerability involves Stored Cross-Site Scripting (XSS) via the 'about_me' parameter in the Ultimate Member WordPress plugin. Detection typically involves inspecting user profile data for injected scripts or unusual HTML content in the 'about_me' field.

Since the vulnerability requires authenticated access with subscriber-level permissions or higher, detection commands should focus on querying the database or web application for suspicious script tags or encoded payloads in the 'about_me' field.

• Use SQL queries on the WordPress database to search for script tags in the 'about_me' user meta field, for example: SELECT * FROM wp_usermeta WHERE meta_key = 'about_me' AND meta_value LIKE '%<script>%';
• Use curl or similar tools to authenticate as a subscriber and retrieve profile pages, then grep or scan the HTML output for suspicious script tags or payloads in the 'about_me' section.
• Employ web vulnerability scanners that support authenticated scans and can detect stored XSS vulnerabilities in WordPress plugins.

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Impact Analysis

The impact of this vulnerability includes the potential for attackers to execute arbitrary scripts in the context of other users visiting the injected pages. This can lead to theft of user credentials, session hijacking, defacement, or distribution of malware. Since the attacker needs only subscriber-level access, it lowers the barrier for exploitation within the site.

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Compliance Impact

The vulnerability allows authenticated attackers to inject arbitrary web scripts via the 'about_me' parameter, which can lead to stored cross-site scripting (XSS) attacks. Such vulnerabilities can potentially expose user data or lead to unauthorized actions within the application.

While the provided information does not explicitly mention compliance impacts, stored XSS vulnerabilities can affect compliance with standards like GDPR and HIPAA by risking unauthorized access or disclosure of personal or sensitive data.

Organizations using the affected plugin should consider this vulnerability as a risk to data integrity and confidentiality, which are key aspects of these regulations.

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Mitigation Strategies

The vulnerability affects all versions of the Ultimate Member plugin up to and including 2.11.4. Immediate mitigation steps include updating the plugin to a version later than 2.11.4 where the issue is fixed.

Additionally, restricting subscriber-level users from inputting data into the 'about_me' parameter or disabling the affected functionality temporarily can reduce risk.

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