Authentication bypass vulnerability in Genua GenuGate High Resistance Firewall

Title

Authentication bypass vulnerability

Product

Genua GenuGate High Resistance Firewall

Vulnerable Version

GenuGate <10.1 p4, <9.6 p7, <9.0/9.0 Z p19

Fixed Version

GenuGate 10.1 p4 (G1010_004), 9.6 p7 (G960_007), 9.0 and 9.0 Z p19 (G900_019)

CVE Number

CVE-2021-27215

Impact

critical

Found

01.28.2021

By

Armin Stock (Atos Germany) | SEC Consult Vulnerability Lab

The Genua GenuGate High Resistance Firewall is affected by a critical authentication bypass vulnerability. An unauthenticated attacker is able to successfully login as arbitrary user in the admin web interface, the side channel interface and user web interface, even as root with highest privileges, by manipulating certain HTTP POST parameters during login.

Vendor description

"genugate Firewall: Well Protected Against Attacks. Your level of IT security is determined largely at the interface between the Internet and the local network. The attacks from the outside and the data  sent from the inside pass through this point.

The High Resistance Firewall genugate satisfies the highest requirements: two different firewall systems – an application level gateway and  a packet filter, each on separate hardware – are combined to form a compact solution. genugate is approved for classification levels German and NATO RESTRICTED and RESTREINT UE/EU RESTRICTED. genugate is certified according to CC EAL 4+" 

URL: https://www.genua.de/en/it-security-solutions/high-resistance-firewall-genugate 

Business recommendation

The vendor provides a patched version for the affected products which should be installed immediately.

Customers should also adhere to security best practices such as network segmentation and limiting access to the admin panel. This is also a requirement for certified and approved environments.

Vulnerability overview/description

1) Authentication bypass vulnerability (CVE-2021-27215)

The Admin Web interface, the Sidechannel Web and Userweb interface can use different methods to perform the authentication of a user. A specific authentication method during login does not check the provided data and returns OK for any authentication request. This allows an attacker to login to the admin panel with a user of his choice, e.g the root user with highest privileges or even a non-existing user.

An attacker needs to have network access to the admin interface. Certified and approved environments mandate that the admin interface is only reachable through a strictly separated network. Nevertheless, it is a highly critical security vulnerability and must be patched immediately.

Proof of concept

1) Authentication bypass vulnerability (CVE-2021-27215)

During the authentication requests at the login page of the admin web interface, the Sidechannel Web and Userweb interface, certain HTTP POST parameters are passed to the server. By manipulating a specific parameter method, an attacker is able to bypass the authentication easily and login as arbitrary user.

[ Detailed proof of concept removed ]

A proof of concept video is available at https://youtu.be/Wfj3-6UBkzg

Vulnerable / tested versions

The versions 9.6 p0 and 9.6 p6 of the Genua GenuGate firewall were tested and found to be vulnerable. The p6 version was the latest version at the time of discovery.

The supported and released product versions 9.0, 9.0 Z and 10.1 are affected as well.

Vendor contact timeline

2021-01-29 Contacting vendor through security@genua.de
  Asking for an S/MIME certificate or GnuGP key to be able to send an encrypted report
2021-01-29 Received GnuGP key from vendor and sent encrypted (PGP) report.
2021-01-29 Vendor confirmed the issue and is working on a patch.
2021-02-02 Vendor released a patch for the affected products.
2021-02-15 Informing CERT-Bund and CERT.at about the upcoming advisory release.
2021-02-17 Coordination call with vendor.
2021-03-01 Coordinated release of security advisory.

Solution

The vendor provides a patched version for the affected and supported products which should be installed immediately.

The patch can be downloaded in genugate GUI or by calling 'getpatches' on the command line interface.

Additional information can be viewed at the vendor's support page:
https://kunde.genua.de/en/overview/genugate.html

Workaround

None 

Advisory URL

https://sec-consult.com/vulnerability-lab/ 

EOF A. Stock / @2021