In the need for privacy (with bad or good intentions), people search for tools that can provide anonymous communication online. Tor is well known for that and have existed for a long time as a respected network of multiple layers of hops and encryption (“onion rings”). Just found this interesting article from Aaron M. Johnson et.al. where they have exploited vulnerabilities in Tor network by using traffic correlation attacks.
According to their work; “…there is more than an 80% chance of deanonymization within 6 months by a malicious guard and exit.”
Check out his talk about “Users Get Routed: Traffic Correlation on Tor by Realistic Adversaries” here.
But of course, this does not mean Tor is useless, it just proves you have to configure and use right.