Stored XSS in Surbma Infusionsoft Shortcode WordPress Plugin

Executive Summary

The Surbma | Infusionsoft Shortcode plugin for WordPress has a Stored Cross-Site Scripting (XSS) vulnerability in versions up to and including 2.0.1. This vulnerability arises because the plugin does not properly sanitize or escape user-supplied input in the 'account' and 'id' attributes of the 'infusionsoft-form' shortcode. These inputs are directly inserted into a script tag's src attribute, allowing an attacker with contributor-level access or higher to inject malicious scripts that execute whenever a user views the affected page.

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Impact Analysis

This vulnerability can allow an authenticated attacker with contributor-level access or above to inject arbitrary JavaScript into pages on the affected WordPress site. When other users visit these pages, the malicious scripts execute in their browsers, potentially leading to theft of sensitive information, session hijacking, or other malicious actions. The vulnerability has a CVSS v3.1 base score of 6.4, indicating a medium severity with impacts on confidentiality and integrity.

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Detection Guidance

This vulnerability involves stored cross-site scripting via the 'infusionsoft-form' shortcode in the Surbma | Infusionsoft Shortcode WordPress plugin. Detection involves identifying if your WordPress installation uses this plugin version 2.0.1 or earlier and checking for injected scripts in pages using the shortcode.

You can search your WordPress database for suspicious script injections in posts or pages that use the 'infusionsoft-form' shortcode by running SQL queries to find script tags or unusual content in the 'account' or 'id' shortcode attributes.

Example commands to detect possible exploitation include:

• Using WP-CLI to search posts for suspicious script tags: wp db query "SELECT ID, post_content FROM wp_posts WHERE post_content LIKE '%<script%' AND post_content LIKE '%infusionsoft-form%'"
• Using grep on exported content or backups: grep -r --include='*.php' '<script' /path/to/wordpress/wp-content/
• Checking plugin version via WP-CLI: wp plugin list | grep infusionsoft_shortcode

Additionally, monitoring web traffic for unusual script execution or alerts from web application firewalls may help detect exploitation attempts.

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Mitigation Strategies

To mitigate this vulnerability, immediately update the Surbma | Infusionsoft Shortcode plugin to a version later than 2.0.1 where the issue is fixed.

If an update is not available, consider temporarily disabling the plugin or removing the 'infusionsoft-form' shortcode usage from your site to prevent exploitation.

Restrict contributor-level and higher user permissions to trusted users only, as the vulnerability requires authenticated users with contributor-level access or above to exploit.

Implement web application firewall (WAF) rules to block suspicious script injections and monitor for unusual activity related to the shortcode.

Finally, review your site for any signs of compromise and clean any injected scripts found in posts or pages.

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