osTicket 1.12 - Persistent Cross-Site Scripting

# Exploit Title: osTicket-v1.12 Stored XSS
# Vendor Homepage: https://osticket.com/
# Software Link: https://osticket.com/download/
# Exploit Author: Aishwarya Iyer
# Contact: https://twitter.com/aish_9524
# Website: https://about.me/aish_iyer
# Category: webapps
# CVE: CVE-2019-14750

1. Description

An issue was discovered in osTicket before 1.10.7 and 1.12.x before 1.12.1.
Stored XSS exists in setup/install.php. It was observed that no input
sanitization was provided in the firstname and lastname fields of the
application. The insertion of malicious queries in those fields leads to
the execution of those queries. This can further lead to cookie stealing or
other malicious actions.

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-14750

2. Proof of Concept

Steps to Reproduce:
- While setting up the osTicket application in the setup/install.php page
insert the XSS payload into the first name and last name field.
- After filling in all the other details and clicking on 'continue', it is
observed that there is no validation for the first name and last name field
and the malicious payload is stored and a new agent is created.
- Login as that agent and navigate to "agents" tab where we will find the
inserted payload in the firstname and Lastname field.
- Click on the firstname value and see the payload gets executed

3. Reference

https://github.com/osTicket/osTicket/commit/c3ba5b78261e07a883ad8fac28c214486c854e12
https://github.com/osTicket/osTicket/releases/tag/v1.12.1
https://github.com/osTicket/osTicket/releases/tag/v1.10.7

4. Solution

The vulnerability has been patched by the vendor in the next release which
is osTicket v1.10.7.