Cisco’s Group Encrypted Transport VPN (GET VPN) is a suite of features designed to secure both IP multicast and unicast traffic across private Wide Area Networks (WANs). This technology is crucial for organizations needing to protect sensitive data as it traverses their network infrastructure. GET VPN operates on Cisco IOS devices and effectively combines the Group Domain of Interpretation (GDOI) with IP Security (IPsec) encryption. This combination provides an efficient and scalable method to ensure the confidentiality and integrity of IP communications.
At the heart of GET VPN are the GDOI and its successor, Group Internet Key Exchange version 2 (G-IKEv2) protocols. GDOI, utilizing Internet Key Exchange version 1 (IKEv1), was the original key management protocol. G-IKEv2 emerged as an improvement, adopting the Internet Key Exchange version 2 (IKEv2) protocol. This transition to IKEv2 allows GET VPN to leverage the enhanced capabilities and security features inherent in the newer protocol. Both GDOI and G-IKEv2 function by establishing secure security associations between group members and a central group controller, often referred to as a key server. This architecture ensures that only authorized members can participate in the secure communication group.
While GET VPN provides robust security, it is important to acknowledge potential vulnerabilities. Cisco has identified scenarios where exploitation is theoretically possible. However, these scenarios are not easily achieved and require a significant degree of prior infiltration into the network environment. Specifically, successful exploitation would necessitate compromising the existing key server or establishing a rogue key server. Both methods require attackers to manipulate the communication packets exchanged between the key server and group members within an already authenticated and encrypted session. To establish a rogue key server, an attacker would need administrative access to a group member device, possess the correct pre-shared key and security policies, and have the capability to alter GDOI or G-IKEv2 packets. These stringent requirements highlight that while vulnerabilities exist in controlled lab environments, real-world exploitation is highly complex due to the existing security measures within GET VPN deployments.
