The Onion Router has long been thought to be one of the best methods for maintaining anonymity of internet traffic, and has even been assailed by the NSA as a hard problem, leading them to use workarounds to circumvent the network and attack specific users However, new research presented by a team from the US Naval Research Lab and Georgetown University has found that with specific methods they designed:

“Tor faces even greater risks from traffic correlation than previous studies suggested. An adversary that provides no more bandwidth than some volunteers do today can deanonymize any given user within three months of regular Tor use with over 50% probability and within six months with over 80% probability.”

Traffic correlation and nodes controlled by malicious actors have both been considered as a major risk to TOR  for a significant amount of time. This new research quantifies the problem and the danger to users of the service, and with any luck may lead to changes in the system to mitigate said risks.