CVE-2024-37233

Executive Summary

CVE-2024-37233 is an Improper Authentication vulnerability in the Play.ht WordPress plugin (versions n/a through 3.6.4). This flaw allows an unauthenticated attacker to access functionality that should be constrained by Access Control Lists (ACLs). The vulnerability has a CVSS score of 4.3 (Medium) and an EPSS score of 0.0%, indicating low exploitation likelihood at this time. No public proof-of-concept or exploit code is available. The vendor has not released a patch.

Supply Chain & Package Security

This vulnerability affects the Play.ht WordPress plugin, which is distributed through the WordPress plugin repository and potentially other channels. Users should verify the integrity of their plugin files and monitor for updates from the vendor. Since this is a WordPress plugin, the supply chain risk includes compromised plugin updates or malicious forks.

CVSS Breakdown & Threat Level

• CVSS Score: 4.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: Low
• Integrity Impact: None
• Availability Impact: None

The threat level is considered low due to the lack of public exploits and low EPSS score. However, the vulnerability allows unauthorized access to restricted functionality, which could lead to information disclosure or further exploitation.

Deep Dive & Mechanics

The vulnerability resides in the Play.ht plugin's authentication mechanism. The plugin fails to properly verify user identity before granting access to certain administrative or privileged functions. This allows an unauthenticated attacker to bypass ACLs and access functionality that should be restricted to authenticated users.

The root cause is likely improper implementation of WordPress nonce checks or capability verification in AJAX handlers or REST API endpoints. Attackers can craft HTTP requests to these endpoints without valid authentication tokens, and the plugin processes them as if they were from an authorized user.

Vulnerable vs. Patched Code

Since no patch is available, a comparison cannot be provided. However, the vulnerable code likely contains something like:

// Vulnerable: No capability check
add_action('wp_ajax_nopriv_playht_action', 'handle_playht_action');
function handle_playht_action() {
    // Process request without checking user capabilities
}

A patched version would include:

// Patched: Proper capability check
add_action('wp_ajax_playht_action', 'handle_playht_action');
function handle_playht_action() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized');
    }
    // Process request
}

Exploitation & Lab Setup

Red Team

1. Setup: Install WordPress with Play.ht plugin version 3.6.4 on a local server.
2. Reconnaissance: Identify AJAX endpoints or REST API routes exposed by the plugin.
3. Exploitation: Send crafted HTTP requests to these endpoints without authentication.
4. Example Request:

   POST /wp-admin/admin-ajax.php HTTP/1.1
   Host: target-site.com
   Content-Type: application/x-www-form-urlencoded
   
   action=playht_privileged_action&data=malicious
   

Blue Team

1. Detection: Monitor for unusual access to Play.ht plugin endpoints from unauthenticated users.
2. Honeypot: Create fake endpoints that log attacker IPs and payloads.
3. Response: Block IPs that attempt to access restricted plugin functionality without authentication.

Indicators of Compromise (IOCs)

• Network: HTTP requests to /wp-admin/admin-ajax.php with action parameter containing playht_ prefix from unauthenticated sources.
• Logs: WordPress debug logs showing failed capability checks or unexpected access to plugin functions.
• Files: Modified plugin files or unexpected files in /wp-content/plugins/playht/ directory.

Detection Engineering

YARA Rule

rule CVE_2024_37233_PlayHT_Authentication_Bypass {
    meta:
        description = "Detects Play.ht plugin files vulnerable to CVE-2024-37233"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-37233"
    strings:
        $vuln_func = "wp_ajax_nopriv_" ascii wide nocase
        $playht_prefix = "playht_" ascii wide nocase
    condition:
        $vuln_func and $playht_prefix
}

Sigma Rule

title: CVE-2024-37233 Play.ht Authentication Bypass
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects unauthenticated access to Play.ht plugin AJAX endpoints
author: Valters IT
date: 2024/01/01
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        c-uri: '/wp-admin/admin-ajax.php'
        cs-uri-query: 'action=playht_*'
        sc-status: 200
    condition: selection
falsepositives:
    - Legitimate plugin functionality if misconfigured
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-37233 Play.ht Authentication Bypass"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=playht_"; http_client_body; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Disable the Play.ht plugin until a patch is available.
2. Short-term: Implement a Web Application Firewall (WAF) rule to block unauthenticated requests to Play.ht endpoints.
3. Long-term: Monitor the vendor's website for updates and apply the patch as soon as it is released.
4. Alternative: Consider replacing the plugin with an alternative that has proper authentication mechanisms.

Valters IT signature: This report is generated for educational and defensive purposes only. Unauthorized exploitation of this vulnerability is illegal.