Tor is short for The Onion Router, which is software that offers users a greater degree of privacy when browsing the Internet by routing traffic through a network of worldwide servers. The system is widely used by people who want to conceal their real IP address and mask their web browsing.
The suspicious server was an "exit node" for Tor, which is the last server in the winding chain used to direct web browsing traffic to its destination.
Roger Dingledine, Tor Project's project leader and director, wrote the Russian server has been labeled a bad exit node, which should mean Tor clients will avoid using the server.
The Russian server was found by Josh Pitts, who does penetration testing and security assessments with Leviathan Security Group. He wrote he wanted to find out how common it was to find attackers modifying the binaries of legitimate code in order to deliver malware.
Binaries from large software companies have digital signatures that can be verified to make sure the code hasn't been modified. But Pitts wrote most code isn't signed, and even further, most don't employ TLS (TransportTransport Layer Security) during downloading. TLS is the successor to SSL (Secure Sockets Layer), which encrypts connections between a client and a server. Top-Firmen der Branche Transport