An adversary can combine monitored DNS requests with well-understood website fingerprinting attacks to create a new type of DNS-enhanced correlation attack. This type of attack works well on websites that are infrequently visited over Tor network, such as censored websites for whistleblowers and whistleblowers. The authors say the attack is highly reliable and could be used to deanonymize Tor users. They say the research community has put a lot of effort into modeling correlation attacks and their effect on Tor users. We know of several organizations that are in a position to use these attacks, notably Google.”]
Source: https://freedom-to-tinker.com/2016/09/29/the-effect-of-dns-on-tors-anonymity/