New VPN vulnerability: threat to user security
Researchers have recently identified a serious vulnerability in most VPN applications that can negate the main purpose of such services - protecting Internet traffic. This exploit, dubbed TunnelVision, can reroute user data outside the encrypted tunnel, compromising the privacy and security of the information.
How the TunnelVision vulnerability works and how to protect against it
The TunnelVision attack exploits a weakness in the Dynamic Host Configuration Protocol (DHCP), which distributes IP-addresses to devices connecting to the network. Using option 121 (a special parameter in the DHCP protocol that allows the DHCP server to specify additional routes for traffic on the network), attackers can reroute Internet traffic through their own servers, bypassing the VPN tunnel. As a result, user data can be read, changed, or even blocked while remaining unencrypted.
How TunnelVision attacks work:
- Starting a DHCP server. The attacker creates a malicious DHCP server on the same network that the victim connects to. This could be a public network, such as a cafe or hotel.
- Using DHCP option 121. The DHCP server uses option 121 to change the default traffic routes, sending it not through the VPN tunnel, but through the physical network interface.
- Traffic redirection. Option 121 specifies a route with a higher priority than the default VPN route. As a result, some or all of the Internet traffic goes through the attacker's server instead of using the secure VPN tunnel.
- An attack that is invisible. The VPN application continues to show that the connection is active and secure because the VPN tunnel itself remains open, although the data has already been intercepted. The «Kill Switch» function, designed to break the connection in case of traffic leaks, does not work in this case.
- Traffic analysis and manipulation. An attacker gets the ability to read, change or block data. For example, it can intercept personal messages, passwords, or even inject malware into transferred files.
How to protect yourself from a TunnelVision attack
Although this vulnerability affects most operating systems, there are some measures that can minimize or completely prevent the risk of using TunnelVision:
- Using Android. The Android operating system does not support option 121, which is used for the TunnelVision attack. This makes VPNs on Android devices significantly more secure.
- Using virtual machines. For protection, it is recommended to run a VPN inside a virtual machine. This creates an additional layer of isolation, and even if the main computer is attacked, the VPN data will remain protected inside the virtual environment.
- Connecting via mobile hotspots. Connecting to the internet via mobile networks, such as a hotspot from a phone, significantly reduces the risk of attack, since mobile networks do not use the same vulnerable mechanisms as public Wi-Fi networks.
- Configuring manual routing rules. Advanced users can configure network routes manually so that traffic always goes through the VPN tunnel. This requires knowledge of network commands, but it helps to avoid exposure to malicious routes.
- Limiting the operation of DHCP servers. If the network is under your control, you can configure network devices to block or ignore DHCP responses from unknown servers. This prevents attacks from attackers creating fake DHCP servers on the local network.
- Connection Monitoring. Regularly check whether VPN traffic is actually going through a secure channel. You can use third-party tools to monitor IP-addresses and traffic routes.
- Use system firewalls. Configuring your firewall to block traffic that does not go through the VPN can help prevent data leaks outside the tunnel.
- Use a personal VPN server. One of the most reliable ways to protect yourself is to use a personal VPN server. In this case, there is no risk that someone from another network will be able to interfere with the VPN connection.
The TunnelVision vulnerability poses a serious threat to VPN users, especially when connecting to public networks. However, there are measures that can help protect data, such as using virtual machines, Android devices, or a personal VPN server.
Private VPN server: effective protection against new threats
A private VPN server provides the highest possible level of service and security, as it assumes total control over all network parameters, minimizing the likelihood of an attack.
You can learn more about private VPN servers and buy them on Private VPN server. The FAQ section contains answers to the most popular user questions, and VPN overview materials will provide a detailed understanding of products and trends in the digital technology market.