Attackers can decloak routing-based VPNs (leviathansecurity.com)

Article summary

Researchers have discovered a novel technique, dubbed TunnelVision, that allows attackers to bypass VPN encapsulation and force a target user's traffic off their VPN tunnel using built-in features of DHCP. This technique, also known as decloaking, can be used to snoop on a user's traffic without their knowledge. The vulnerability is possible due to the way VPNs configure routing tables and can be mitigated by using network namespaces on Linux-based operating systems. A fix exists, but it may introduce a side channel that could be used for targeted denial-of-service censorship.

Main themes

• VPN security
• DHCP vulnerabilities
• Network routing
• Linux security
• VPN configuration

What commenters say

• The vulnerability can be mitigated by implementing a kill switch firewall rule that blocks off-VPN traffic, which is a common feature in many VPNs.
• Some argue that the vulnerability is not a significant threat, as a simple leak protection firewall rule can completely negate the attack.
• Others claim that the vulnerability is more complex and requires a deeper understanding of routing tables and network configuration to properly mitigate.
• The use of network namespaces on Linux-based operating systems can provide a effective mitigation against the vulnerability.
• Some VPN providers may not implement kill switches correctly, making them vulnerable to the attack.
• The vulnerability highlights the importance of properly configuring VPNs and understanding the underlying network routing and security mechanisms.
• There is disagreement among commenters about the effectiveness of different mitigation strategies and the severity of the vulnerability.