osTicket 1.12 - Formula Injection

# Exploit Title: osTicket-v1.12 Formula Injection
# 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-2019-14749

1. Description


An issue was discovered in osTicket before 1.10.7 and 1.12.x before 1.12.1.
CSV (aka Formula) injection exists in the export spreadsheets
functionality. These spreadsheets are generated dynamically from
unvalidated or unfiltered user input in the Name and Internal Notes fields
in the Users tab, and the Issue Summary field in the tickets tab. This
allows other agents to download data in a .csv file format or .xls file
format. This is used as input for spreadsheet applications such as Excel
and OpenOffice Calc, resulting in a situation where cells in the
spreadsheets can contain input from an untrusted source. As a result, the
end user who is accessing the exported spreadsheet can be affected.

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-14749

2. Proof of Concept

Steps to Reproduce:
- Login as an agent and under the "Users" section create a new user.
- Insert the crafted payload of Formula Injection into "Name" and "Internal
Notes" field.
- Login as another agent and under the Users tab, click on export and then
save the ".csv" file.
- It is observed that the payload gets executed in excel and this leads to
remote code execution.
- Not just an agent, even a non-agent user has the option to edit his name
where he can insert the malicious payload of Formula Injection.
- The application does not sanitize the inputs here due to which when the
agent clicks on export the payload gets executed.
-The same issue persisted in the "Issue Summary" field in the tickets tab.

3. Reference

https://github.com/osTicket/osTicket/commit/99818486c5b1d8aa445cee232825418d6834f249
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.