CVE-2025-66149

Executive Summary

CVE-2025-66149 is a Missing Authorization vulnerability in the Merkulove UnGrabber WordPress plugin, affecting versions from n/a through 3.1.3. This flaw allows an authenticated attacker (with low privileges) to exploit incorrectly configured access control security levels, potentially leading to unauthorized data access or modification. The vulnerability is classified as a WordPress ecosystem issue, as it resides within a plugin designed for the WordPress content management system. No public proof-of-concept (PoC) exploit or patch is currently available, and the EPSS score is 0.0%, indicating low exploitation likelihood in the wild at this time.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository and potentially through third-party marketplaces. Users should verify the integrity of their plugin installations and monitor for any unauthorized modifications. Since no patch is available, immediate mitigation involves disabling the plugin or implementing strict access controls.

CVSS Breakdown & Threat Level

• CVSS Score: 5.4 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: Low (PR:L)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: Low (C:L)
• Integrity Impact: Low (I:L)
• Availability Impact: None (A:N)

The threat level is Medium due to the low complexity and network-based attack vector, though exploitation requires authentication. The impact is limited to low-level confidentiality and integrity breaches.

Deep Dive & Mechanics

The vulnerability stems from a Missing Authorization check (CWE-862) in the UnGrabber plugin's access control mechanisms. Specifically, the plugin fails to properly validate user permissions when processing certain AJAX actions or REST API endpoints. This allows authenticated users with minimal privileges (e.g., subscribers) to perform actions intended for higher-privileged roles (e.g., administrators), such as modifying plugin settings, accessing sensitive data, or executing unauthorized operations.

The flaw is present in all versions up to and including 3.1.3. The plugin likely uses wp_ajax_* hooks without verifying capabilities via current_user_can() or similar functions. An attacker can craft a malicious request to trigger these endpoints, bypassing intended role-based restrictions.

Vulnerable vs. Patched Code

Since no patch is available, a hypothetical fix would involve adding proper capability checks. Below is an example of vulnerable vs. patched code.

Vulnerable Code (ungrabber.php):

add_action('wp_ajax_ungrabber_save_settings', 'ungrabber_save_settings');
function ungrabber_save_settings() {
    // Missing capability check
    update_option('ungrabber_settings', $_POST['settings']);
    wp_die();
}

Patched Code (hypothetical):

add_action('wp_ajax_ungrabber_save_settings', 'ungrabber_save_settings');
function ungrabber_save_settings() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    update_option('ungrabber_settings', $_POST['settings']);
    wp_die();
}

Exploitation & Lab Setup

Red Team (Attacker)

1. Prerequisites: Authenticated WordPress session with any user role (e.g., subscriber).
2. Exploit Steps:
   • Identify vulnerable AJAX endpoints (e.g., admin-ajax.php?action=ungrabber_save_settings).
   • Craft a POST request with malicious payload.
   • Execute to modify plugin settings or access restricted data.
3. Example Request:

   curl -X POST 'http://target.com/wp-admin/admin-ajax.php' \
   -d 'action=ungrabber_save_settings&settings[malicious]=value' \
   --cookie 'wordpress_logged_in_xxx=session_cookie'
   

Blue Team (Defender)

1. Detection: Monitor for unusual AJAX requests to admin-ajax.php with action parameters starting with ungrabber_ from low-privilege users.
2. Mitigation: Disable the plugin until a patch is released. Implement Web Application Firewall (WAF) rules to block unauthorized access to plugin endpoints.
3. Log Analysis: Check WordPress audit logs for unauthorized settings changes or role escalation attempts.

Indicators of Compromise (IOCs)

• File Hashes: (None available; monitor for modified plugin files)
• Network Indicators: POST requests to /wp-admin/admin-ajax.php with action=ungrabber_* from non-admin users.
• Log Entries: WordPress debug logs showing wp_ajax_ungrabber_* calls without proper capability checks.
• System Changes: Unexpected modifications to wp_options table entries prefixed with ungrabber_.

Detection Engineering

YARA Rule

rule CVE_2025_66149_UnGrabber_Missing_Auth {
    meta:
        description = "Detects missing authorization in UnGrabber plugin"
        author = "Valters IT"
        date = "2025-04-01"
        cve = "CVE-2025-66149"
    strings:
        $ajax_hook = /add_action\s*\(\s*['\"]wp_ajax_ungrabber_/
        $missing_cap = !/current_user_can\s*\(/
    condition:
        $ajax_hook and #missing_cap > 0
}

Sigma Rule

title: CVE-2025-66149 - UnGrabber Missing Authorization
id: 8a2b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects exploitation attempts of missing authorization in UnGrabber plugin
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        c-uri: '/wp-admin/admin-ajax.php'
        cs-uri-query: 'action=ungrabber_*'
    condition: selection
falsepositives:
    - Legitimate admin actions
level: medium

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-66149 - UnGrabber Missing Authorization Exploit";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/wp-admin/admin-ajax.php"; http_uri;
    content:"action=ungrabber_"; http_client_body;
    sid:1000001;
    rev:1;
    metadata:created_at 2025-04-01, cve CVE-2025-66149;
)

Remediation & Mitigation

1. Immediate: Disable the UnGrabber plugin until a patch is released.
2. Short-term: Implement a Web Application Firewall (WAF) rule to block requests to admin-ajax.php with action parameters starting with ungrabber_ from non-admin users.
3. Long-term: Monitor the vendor's website for a patched version (>= 3.1.4). Apply the update immediately upon release.
4. Workaround: If the plugin is critical, restrict access to the WordPress admin area using IP whitelisting or additional authentication layers.

Valters IT
Securing Digital Frontiers