Attacks against Tor relays

Tor security relies on the low chance of attackers controlling multiple Tor relays, but notable breaches occurred in 2014 and 2020. Key incidents include traffic confirmation and Sybil-style relay deployments that compromised a portion of the network, emphasizing ongoing risks and the need for vigilance and configuration best practices.
Hashtags: #TorSecurityAdvisory #RelayEarly #SSLStrip #GuardRelays #ExitRelays

Keypoints

  • In 2014, attackers deployed many relays to deanonymize hidden services and users for over five months.
  • The 2014 attack combined a traffic confirmation method with a Sybil attack affecting about 6.4% of Guard capacity.
  • In 2020, attackers controlled roughly 20% of exit relay capacity and targeted unencrypted HTTP traffic to intercept data.
  • Around 23% of exit capacity was malicious in May 2020, followed by another ~19% in June 2020, prompting shutdowns.
  • Ongoing defense relies on nine hard-coded Directory Authority nodes, consensus-based trust, and continuous monitoring for anomalous relays.

Read More: https://deepweb.net/blog/newest/attacks-against-tor-relays