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Issue: Stored Cross-Site Scripting  
  
CVE: CVE-2019-13182  
  
Security researcher: Richard Tan @ The Missing Link Security  
  
Product name: Serv-U FTP Server  
  
Product version: Tested on 15.1.7  
  
Fixed in: Serv-U 15.1.7 Hotfix 2  
  
  
  
# Overview  
  
The application is vulnerable to a stored cross-site scripting  
vulnerability.The user's "Full Name" field and "HTTP Login Title Text" field  
lacked input validation allowing Javascript code to be inserted and executed  
in the context the user's browser session either when the victim logs to the  
web client or browses to the Serv-U server login page.  
  
A privilege user could manipulate the affected parameter on an existing  
user's account so that Javascript is executed on the client's browser when  
the victim logs into his account.  
  
For example, a successful XSS attack could result in the attacker  
redirecting the user to a phishing/malicious site or performing actions as  
the victim on the Serv-U application.  
  
  
  
**Injection Point in user properties**  
  
* Full Name  
  
* HTTP Login Title Text  
  
  
  
# Proof of concept  
  
1) Login as a user that has privileges to create or modify users.  
  
2) Create a new user and add the following payload into the "Fullname"  
parameter.  
<script>window.location.replace("http://www.example.com");</script>  
  
3) Login as the victim user and observe the user being redirected to  
www.example.com <http://www.example.com> when accessing the web client.  
Note that exploiting the "HTTP Login Title Text" field means that the  
Javascript payload will be executed when any user browses to the Serv-U  
login page.