CVE-2025-39507

Executive Summary

CVE-2025-39507 is a critical PHP Local File Inclusion (LFI) vulnerability discovered in the Nasa Core WordPress plugin (nasa-core) developed by NasaTheme. The vulnerability stems from improper control of a filename used in a PHP include/require statement, allowing an unauthenticated attacker to include arbitrary local files from the server. This can lead to sensitive information disclosure, including configuration files, database credentials, and potentially source code. The CVSS score of 7.5 (High) reflects the ease of exploitation and the potential for significant data exposure. As a WordPress plugin vulnerability, it affects sites running Nasa Core versions prior to 6.4.4. No public proof-of-concept (PoC) or exploit code has been released at this time, but the risk remains high due to the nature of LFI attacks.

Supply Chain & Package Security

This vulnerability is specific to the WordPress ecosystem and the Nasa Core plugin. It is not an NPM, PyPI, Go, or Ruby package. The supply chain risk is limited to WordPress sites that have installed this plugin. Administrators should verify they are not using a vulnerable version and monitor for updates from the vendor.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
• Base Score: 7.5 (High)
• Attack Vector: Network (AV:N) – Exploitable remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No user action required.
• Scope: Unchanged (S:U) – Vulnerability does not affect other components.
• Confidentiality Impact: High (C:H) – Full file read access.
• Integrity Impact: None (I:N) – No file modification.
• Availability Impact: None (A:N) – No denial of service.

Threat Level: High. The vulnerability is trivial to exploit and can expose sensitive server files.

Deep Dive & Mechanics

The vulnerability is a PHP Local File Inclusion (LFI) caused by improper control of a filename used in a PHP include/require statement. In the Nasa Core plugin, a parameter (likely file, template, or similar) is passed to a function that constructs a file path without proper sanitization. An attacker can manipulate this parameter to include arbitrary files from the server, such as /etc/passwd, /wp-config.php, or log files.

The core issue is that the plugin uses user-supplied input directly in a PHP include() or require() statement without validating the path. For example:

include($_GET['file'] . '.php');

This allows path traversal sequences like ../../../../etc/passwd%00 to bypass the .php extension (via null byte injection on older PHP versions) or simply include files without the extension if the code does not append one.

Vulnerable vs. Patched Code

Vulnerable Code (versions < 6.4.4):

// Example vulnerable function in nasa-core
function nasa_load_template($template) {
    include(plugin_dir_path(__FILE__) . 'templates/' . $template . '.php');
}

The $template parameter is taken directly from user input (e.g., $_GET['template']) without sanitization.

Patched Code (version 6.4.4 and later):

// Patched version
function nasa_load_template($template) {
    $allowed_templates = array('default', 'custom', 'grid');
    $template = basename($template); // Remove path traversal
    if (in_array($template, $allowed_templates)) {
        include(plugin_dir_path(__FILE__) . 'templates/' . $template . '.php');
    } else {
        // Fallback or error
    }
}

The patch uses basename() to strip directory traversal and validates the input against a whitelist of allowed templates.

Exploitation & Lab Setup

Red Team

Prerequisites:

• A WordPress site with Nasa Core plugin version < 6.4.4.
• Knowledge of the vulnerable parameter (e.g., template, file, page).

Exploitation Steps:

1. Identify the vulnerable endpoint: The plugin likely exposes an AJAX action or shortcode that accepts a file parameter. Common patterns include:

   • /?nasa_action=load_template&template=../../../../etc/passwd
   • /wp-admin/admin-ajax.php?action=nasa_load&file=../../../../etc/passwd

2. Craft the payload: Use path traversal to read sensitive files:

   ../../../../etc/passwd
   ../../../../wp-config.php
   ../../../../../../var/log/apache2/access.log (for log poisoning)
   

3. Execute the attack: Send the crafted request using curl:

   curl "http://target.com/?nasa_action=load_template&template=../../../../etc/passwd"
   

4. Read output: The file content will be displayed in the response.

Note: No public exploit code is available, but the technique is standard LFI.

Blue Team

Detection & Response:

1. Monitor web server logs for suspicious path traversal patterns:

   • \.\./ sequences
   • Requests to /etc/passwd, /wp-config.php, etc.
   • Unusual parameters like template=, file=, page=.

2. Deploy WAF rules to block path traversal:

   • Block requests containing ../ or ..\\.
   • Block requests to known sensitive files.

3. Harden the server:

   • Disable allow_url_include in php.ini.
   • Use open_basedir to restrict file access.
   • Keep the plugin updated to version 6.4.4 or later.

Indicators of Compromise (IOCs)

• File paths accessed:

  • /etc/passwd
  • /etc/shadow
  • /wp-config.php
  • /var/log/apache2/access.log
  • /proc/self/environ

• URL patterns:

  • ?nasa_action=load_template&template=
  • ?action=nasa_load&file=
  • ?page=../../../../

• Log entries:

  • GET /?nasa_action=load_template&template=../../../../etc/passwd
  • GET /wp-admin/admin-ajax.php?action=nasa_load&file=../../../../wp-config.php

Detection Engineering

YARA Rule

rule CVE_2025_39507_Nasa_Core_LFI {
    meta:
        description = "Detects attempts to exploit CVE-2025-39507 LFI in Nasa Core plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-39507"
    strings:
        $path_traversal = /\.\.\/|\.\.\\/
        $sensitive_file = /etc\/passwd|wp-config\.php|proc\/self\/environ/
        $vuln_param = /nasa_action|nasa_load|template=|file=/
    condition:
        any of ($path_traversal) and any of ($sensitive_file) and any of ($vuln_param)
}

Sigma Rule

title: CVE-2025-39507 Nasa Core LFI Detection
id: 8a4b3c2d-1e5f-6a7b-8c9d-0e1f2a3b4c5d
status: experimental
description: Detects HTTP requests attempting to exploit LFI in Nasa Core plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains:
            - 'nasa_action=load_template'
            - 'action=nasa_load'
            - 'template='
            - 'file='
        cs-uri-query|contains:
            - '../'
            - '..\\'
            - '/etc/passwd'
            - '/wp-config.php'
    condition: selection
falsepositives:
    - Legitimate use of similar parameters (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-39507 Nasa Core LFI Attempt"; flow:to_server,established; content:"GET"; http_method; content:"nasa_action=load_template"; http_uri; content:"../"; http_uri; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Update the plugin to version 6.4.4 or later if a patch becomes available.
2. If no patch is available, disable or remove the Nasa Core plugin until a fix is released.
3. Implement a Web Application Firewall (WAF) rule to block path traversal patterns.
4. Restrict file access using PHP open_basedir and disable allow_url_include.

Long-term Measures:

• Regularly update all WordPress plugins and themes.
• Conduct code reviews for custom plugins to ensure input validation.
• Monitor vendor channels for security advisories.

Valters IT Signature

This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters-it.com.