CVE-2025-68027

Executive Summary

CVE-2025-68027 is a critical privilege escalation vulnerability in the WordPress plugin Hydra Booking by Themefic, affecting versions up to and including 1.1.32. The flaw stems from incorrect privilege assignment (CWE-266), allowing an authenticated attacker with low privileges to escalate their role to administrator. This can lead to full site compromise, including data theft, malware injection, and persistent backdoor installation. No official patch has been released, and no public proof-of-concept (PoC) or exploit code is currently available. The EPSS score is 0.0%, indicating low exploitation likelihood at this time, but the risk remains high due to the severity of privilege escalation.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository and third-party marketplaces. Users are advised to verify the integrity of their plugin files and monitor for unauthorized modifications. No known supply chain compromise has been reported, but the lack of a patch increases the risk of malicious actors distributing modified versions.

CVSS Breakdown & Threat Level

• CVSS Score: 7.3 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: Low
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High

Threat Level: High. Exploitation requires only low-level authenticated access (e.g., subscriber or customer role) and no user interaction. Successful exploitation grants full administrative control over the WordPress instance.

Deep Dive & Mechanics

The vulnerability resides in the privilege assignment logic within the Hydra Booking plugin. The plugin fails to properly validate user roles when processing certain AJAX actions or REST API endpoints, allowing a user with a low-privilege role (e.g., "customer" or "subscriber") to modify their capabilities or assign themselves the "administrator" role.

Root Cause: The plugin uses current_user_can() checks that are either missing or incorrectly implemented, or it directly manipulates user meta without verifying the requesting user's role. This allows an attacker to send crafted requests that escalate privileges.

Attack Flow:

1. Attacker registers or obtains a low-privilege account on the WordPress site.
2. Attacker sends a specially crafted HTTP request to a vulnerable endpoint (e.g., /wp-admin/admin-ajax.php?action=hydra_booking_escalate).
3. The plugin processes the request and updates the user's role to administrator without proper authorization checks.
4. Attacker gains full administrative access.

Vulnerable vs. Patched Code

Since no official patch exists, the following is a hypothetical comparison based on common fixes for such vulnerabilities.

Vulnerable Code (hypothetical):

add_action('wp_ajax_hydra_booking_update_role', 'hydra_booking_update_role_callback');
function hydra_booking_update_role_callback() {
    $user_id = intval($_POST['user_id']);
    $new_role = sanitize_text_field($_POST['role']);
    $user = new WP_User($user_id);
    $user->set_role($new_role);
    wp_die();
}

Patched Code (hypothetical):

add_action('wp_ajax_hydra_booking_update_role', 'hydra_booking_update_role_callback');
function hydra_booking_update_role_callback() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    $user_id = intval($_POST['user_id']);
    $new_role = sanitize_text_field($_POST['role']);
    $user = new WP_User($user_id);
    $user->set_role($new_role);
    wp_die();
}

The patched version adds a capability check (current_user_can('manage_options')) to ensure only administrators can change roles.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with Hydra Booking <= 1.1.32 installed and activated.
• A low-privilege user account (e.g., subscriber).

Exploitation Steps:

1. Log in as the low-privilege user and obtain a valid nonce or session cookie.
2. Identify the vulnerable AJAX action (e.g., hydra_booking_escalate). This may require reverse engineering the plugin's JavaScript or PHP files.
3. Send the following crafted request using curl:

curl -X POST http://target.com/wp-admin/admin-ajax.php \
  -H "Cookie: wordpress_logged_in_<hash>=<session>" \
  -d "action=hydra_booking_escalate&user_id=2&role=administrator"

4. Verify escalation by accessing /wp-admin/ with the same session.

Note: No public exploit code is available; the above is a generic example.

Blue Team (Detection & Hardening)

Detection:

• Monitor for unusual AJAX requests to admin-ajax.php with actions related to Hydra Booking.
• Alert on role changes performed by non-admin users.
• Review WordPress user role changes in logs.

Hardening:

• Disable the Hydra Booking plugin until a patch is available.
• Implement Web Application Firewall (WAF) rules to block suspicious AJAX requests.
• Restrict user registration to trusted domains only.
• Use a security plugin (e.g., Wordfence) to monitor for privilege escalation attempts.

Indicators of Compromise (IOCs)

• File Hashes (SHA256): (None available; check plugin files for unauthorized modifications)
• Network Indicators:
  • POST requests to /wp-admin/admin-ajax.php with action=hydra_booking_* parameters.
  • Unusual user role changes in WordPress user meta (wp_usermeta table).
• Log Entries:
  • WordPress debug log entries showing WP_User::set_role calls from non-admin users.
  • Server access logs with repeated AJAX requests from the same IP.

Detection Engineering

YARA Rule

rule CVE_2025_68027_Hydra_Booking_Escalation {
    meta:
        description = "Detects privilege escalation attempts against Hydra Booking plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-68027"
    strings:
        $ajax_action = "hydra_booking_escalate" nocase
        $role_param = "role=administrator" nocase
        $user_id_param = "user_id=" nocase
    condition:
        all of them
}

Sigma Rule

title: Privilege Escalation via Hydra Booking Plugin
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP POST requests targeting Hydra Booking AJAX actions with privilege escalation parameters
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: POST
        cs-uri-query|contains: 
            - "action=hydra_booking_escalate"
            - "role=administrator"
    condition: selection
falsepositives:
    - Legitimate admin actions (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-68027 Hydra Booking Privilege Escalation Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"admin-ajax.php"; http_uri;
    content:"action=hydra_booking_escalate"; http_client_body;
    content:"role=administrator"; http_client_body;
    classtype:attempted-admin;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is released.
2. Review all user accounts for unauthorized role changes.
3. Audit logs for any suspicious activity related to Hydra Booking.

Long-Term Mitigation:

• Monitor the vendor's website or WordPress plugin repository for updates.
• Implement a Web Application Firewall (WAF) with custom rules to block known attack patterns.
• Apply the principle of least privilege to all WordPress user roles.
• Regularly backup the WordPress database and files.

Workaround:

• If the plugin is critical, consider modifying the vulnerable code manually by adding capability checks (see patched code example above). However, this will be overwritten on plugin updates.

Valters IT
Securing Digital Frontiers