Identify Tor, VPN, and proxy traffic is a popular method for improving privacy and security on the internet. Its essential component, the Tor exit node, acts as a bridge between the anonymizing environment and the public Internet, allowing users to bypass censorship without the risk of detection. The process of browsing through Tor works by routing encrypted traffic through multiple random servers, called relays (represented as slices of onion) until reaching the last one in the circuit (the exit node), where it then sends that data out to its destination on the internet.

Its utility as a tool for privacy advocates and citizens in oppressive regimes is well known, but it’s also commonly used by hackers and other bad actors to conceal malicious activity. The ability to identify Tor use, leveraging network, endpoint, and security appliance logs and indicator- or behavior-based analysis, can help defenders take action.

Identify Tor, VPN, and Proxy Traffic: Enhance Network Security

Aside from preventing unauthorized access, the threat of malicious activities routed through Tor can be mitigated by ensuring that all data on networks is protected with strong encryption and authentication. In addition, by examining evidence of substantial transactions with Tor exit nodes revealed in netflow, packet capture (PCAP), and web server logs, organizations can detect suspicious activity that could indicate reconnaissance, exploitation, command and control communication or data exfiltration. This can be particularly beneficial for organizations subject to regulatory compliance or requiring strict access controls, such as banks and financial institutions. Lastly, by implementing challenge-response tests and requiring that all traffic to internet-exposed services be encrypted with secure TLS, organizations can reduce the information available to malicious actors seeking to evade defensive measures.