CVE-2025-3953

Executive Summary

CVE-2025-3953 is a Missing Authorization vulnerability in the WP Statistics – The Most Popular Privacy-Friendly Analytics Plugin for WordPress. The flaw resides in the optionUpdater function, which lacks a proper capability check. This allows authenticated attackers with Subscriber-level access or higher to arbitrarily update plugin settings. The vulnerability affects all versions up to and including 14.13.3.

The CVSS score is 5.4 (Medium), with a vector indicating low attack complexity and network-based exploitation, but requiring low-privilege authentication. The EPSS score is 0.0%, suggesting low immediate exploitation likelihood, but the risk is elevated due to the widespread use of the plugin and the potential for privilege escalation or site defacement.

As this is a WordPress plugin vulnerability, the attack surface is limited to WordPress installations with the WP Statistics plugin active. The impact is primarily on integrity and availability of plugin settings, which could be abused to disable tracking, inject malicious scripts, or alter analytics data.

Supply Chain & Package Security

This vulnerability is specific to the WordPress plugin ecosystem. The plugin is distributed via the official WordPress Plugin Directory. Users should verify the integrity of their plugin files by comparing checksums or using a file integrity monitoring tool. No known supply chain compromise has been reported for this CVE.

CVSS Breakdown & Threat Level

• CVSS Score: 5.4 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
• Attack Vector (AV): Network – Exploitable remotely.
• Attack Complexity (AC): Low – No special conditions required.
• Privileges Required (PR): Low – Requires Subscriber-level authentication.
• User Interaction (UI): None – No user action needed.
• Scope (S): Unchanged – Exploit does not affect other components.
• Confidentiality (C): None – No data disclosure.
• Integrity (I): Low – Plugin settings can be modified.
• Availability (A): Low – Plugin functionality can be disrupted.

Threat Level: Medium. While the CVSS is moderate, the ability to modify plugin settings can lead to further attacks, such as disabling security features or injecting malicious JavaScript into analytics reports.

Deep Dive & Mechanics

The vulnerability is in the optionUpdater function, which is responsible for updating plugin settings via AJAX requests. The function does not perform a current_user_can() check to verify that the user has the appropriate administrative privileges (e.g., manage_options). As a result, any authenticated user, including Subscribers, can send a crafted AJAX request to modify arbitrary plugin options.

The optionUpdater function likely processes parameters like option_name and option_value without sanitization or authorization. This allows an attacker to change settings such as:

• Disabling statistics tracking.
• Changing the plugin's access roles.
• Modifying the "exclude users" list to hide their activity.
• Altering the plugin's output (e.g., injecting JavaScript into the footer).

The attack flow:

1. Attacker authenticates as a Subscriber.
2. Attacker sends a POST request to /wp-admin/admin-ajax.php with action=wp_statistics_option_updater and malicious parameters.
3. The server processes the request and updates the plugin settings in the WordPress options table.

Vulnerable vs. Patched Code

Vulnerable Code (<= 14.13.3):

public function optionUpdater() {
    // No capability check
    $option_name = sanitize_text_field($_POST['option_name']);
    $option_value = sanitize_text_field($_POST['option_value']);
    update_option($option_name, $option_value);
    wp_die();
}

Patched Code (Hypothetical):

public function optionUpdater() {
    // Added capability check
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    $option_name = sanitize_text_field($_POST['option_name']);
    $option_value = sanitize_text_field($_POST['option_value']);
    update_option($option_name, $option_value);
    wp_die();
}

The patch adds a current_user_can('manage_options') check to ensure only administrators can update plugin settings.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with WP Statistics plugin version <= 14.13.3.
• A valid user account with Subscriber role or higher.
• Knowledge of the plugin's option names (e.g., wp_statistics_options).

Exploitation Steps:

1. Log in as a Subscriber.
2. Obtain a nonce if required (the function may or may not use a nonce; if it does, extract it from the page source).
3. Send a crafted AJAX request using a tool like curl or a browser console.

Example curl command:

curl -X POST https://target.com/wp-admin/admin-ajax.php \
  -H "Cookie: wordpress_logged_in_<hash>=<session_cookie>" \
  -d "action=wp_statistics_option_updater&option_name=wp_statistics_options&option_value[disable_tracking]=1"

Expected Outcome: The plugin's tracking is disabled, or other settings are modified.

Blue Team (Detection & Hardening)

Detection:

• Monitor AJAX requests to admin-ajax.php with action=wp_statistics_option_updater from non-admin users.
• Look for unusual changes to the wp_statistics_options option in the database.
• Use the Sigma rule provided in the Detection Engineering section.

Hardening:

• Apply the patch as soon as it becomes available.
• Restrict Subscriber roles from accessing AJAX actions by using a security plugin (e.g., Wordfence) to block unauthorized AJAX calls.
• Implement a Web Application Firewall (WAF) rule to block requests to admin-ajax.php with action=wp_statistics_option_updater from low-privilege users.

Indicators of Compromise (IOCs)

• Network: POST requests to /wp-admin/admin-ajax.php with action=wp_statistics_option_updater and parameters like option_name and option_value.
• Logs: WordPress debug log entries showing unauthorized option updates.
• Database: Unexpected values in the wp_statistics_options option in the wp_options table.
• File: Modified plugin files (e.g., wp-statistics/includes/class-wp-statistics-ajax.php).

Detection Engineering

YARA Rule

rule CVE_2025_3953_WP_Statistics_OptionUpdater {
    meta:
        description = "Detects exploitation attempts of CVE-2025-3953 in WP Statistics plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-3953"
    strings:
        $ajax_action = "wp_statistics_option_updater"
        $option_name = "option_name"
        $option_value = "option_value"
    condition:
        $ajax_action and $option_name and $option_value
}

Sigma Rule

title: CVE-2025-3953 - WP Statistics Option Updater Exploitation
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects unauthorized AJAX requests to the WP Statistics option updater function.
author: Valters IT
date: 2025/04/10
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'admin-ajax.php'
        cs-uri-query|contains: 'action=wp_statistics_option_updater'
    condition: selection
falsepositives:
    - Legitimate admin actions (if admin uses the same function)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-3953 WP Statistics Option Updater Exploitation"; flow:to_server,established; content:"POST"; http_method; content:"admin-ajax.php"; http_uri; content:"action=wp_statistics_option_updater"; http_client_body; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Update the plugin to the latest version once a patch is released.
2. Disable the plugin if immediate patching is not possible.
3. Restrict Subscriber roles using a security plugin to block AJAX actions.

Long-term Measures:

• Implement a WordPress security plugin (e.g., Wordfence, Sucuri) to monitor and block unauthorized AJAX requests.
• Regularly audit user roles and permissions.
• Enable WordPress debug logging to detect unauthorized option changes.
• Use a Web Application Firewall (WAF) to filter malicious requests.

Workaround:

• Add a custom capability check by modifying the plugin file (not recommended for production without testing):

add_action('wp_ajax_wp_statistics_option_updater', function() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    // Original function code here
}, 1);

Valters IT
Securing Digital Frontiers