Characterizing the VPN Ecosystem in the Wild

The COVID-19 pandemic has led to a significant increase in the use of Virtual Private Networks (VPNs) around the world, as remote work and online activities have become more prevalent. As a result, it is now more important than ever to measure the traffic and security aspects of the VPN ecosystem. However, detecting and characterizing VPN traffic remains challenging due to some VPN protocols using the same port number as web traffic. This makes port-based traffic classification ineffective, and VPN users are also concerned about their connections' vulnerabilities due to privacy issues. To address these challenges, this paper aims at detecting and characterizing VPN servers in the wild, which facilitates identifying VPN traffic. The authors perform Internet-wide active measurements to find VPN servers worldwide and analyze their cryptographic certificates, vulnerabilities, locations, and fingerprints. They identify 9.8 million VPN servers distributed globally using OpenVPN, SSTP, PPTP, and IPsec protocols. The study finds that SSTP is the most vulnerable protocol among those detected with over 90% of servers being vulnerable to TLS downgrade attacks. Additionally, out of all the servers that respond to their VPN probes, 2% also respond to HTTP probes and are classified as Web servers. The authors apply their list of VPN servers to identify VPN traffic in a large European ISP's network and observe that 2.6% of all traffic is related to these VPN servers. This research provides valuable insights into the state of security for VPN solutions used by individuals and organizations worldwide. The findings can help improve security measures for both users and providers while highlighting areas where further research is needed to enhance privacy protection for online activities.

The Impact of the COVID-19 Pandemic on VPN Use

As remote work and online activities have become more prevalent due to the COVID-19 pandemic, it is now more important than ever to measure the traffic and security aspects of Virtual Private Networks (VPNs). This paper aims at detecting and characterizing VPN servers in the wild, which facilitates identifying VPN traffic. The authors perform Internet-wide active measurements to find 9.8 million VPN servers distributed globally using OpenVPN, SSTP, PPTP, and IPsec protocols.

Due to some VPN protocols using the same port number as web traffic, port-based traffic classification has become ineffective for detecting and characterizing VPNs. Additionally, users are concerned about their connections' vulnerabilities due to privacy issues. To address these challenges, this research provides valuable insights into the state of security for VPN solutions used by individuals and organizations worldwide.

The authors analyze cryptographic certificates, vulnerabilities, locations, and fingerprints of identified 9.8 million global VPN servers. They find that SSTP is most vulnerable protocol among those detected with over 90% of servers being vulnerable to TLS downgrade attacks.