Zendesk App SweetHawk Survey 1.6 - Persistent Cross-Site Scripting

# Exploit Title: Zendesk App SweetHawk Survey 1.6 - Persistent Cross-Site Scripting
# Date: 2019-12-17
# Exploit Author: MTK
# Vendor Homepage: https://sweethawk.co/zendesk/survey-app
# Software Link: https://www.zendesk.com/apps/support/survey/
# Version: Up to v1.6
# Tested on: Zendesk - Firefox/Windows

# Software description:
# Sweet Hawk Survey app ask customers for a 0-10 score instead of the normal good or bad question. 
# You can get more granular satisfaction data without compromising the response rate. 
# Ask an optional NPS question on the landing page. View reports and drill down into the response 
# detail and go directly to the ticket. Easy to set up, just replace the survey place holder in 
# your trigger or automation. Customize the landing pages for each of your brands.

# Technical Details & Impact:
# Attackers use vulnerable web pages to inject malicious code and have it stored on the web server 
# for later use. The payload is automatically served to users who browse web pages and executed in 
# their context. Thus, the victims do not need to click on a malicious link to run the payload. 
# All they have to do is visit a vulnerable web page.

# POC

1. Open Support ticket in Zendesk and send XSS payload e.g;
<script>alert(1);</script>
2. Generate survey  request to rate the ticket and payload will execute;

# Time line
09-19-2019 - Vulnerability discovered
09-20-2019 - Vendor contacted
12-02-2019 - Detailed report shared and full disclosure time line given with no response
12-17-2019 - Full Disclosure