A group of 115 malicious fast non-exit relays (6.4% of whole Tor network) were actively monitoring the relays on both ends of a Tor circuit in an effort to de-anonymize users. Tor is an encrypted anonymizing network considered to be one of the most privacy oriented service, which is used by online users in order to hide their activities from law enforcement, government censors and others. Users who operated or accessed hidden services from early February through July 4 should assume they were affected.
Source: https://thehackernews.com/2014/07/attackers-compromise-tor-network-to-de.html