Compromising Anonymity Using Packet Spinning.pdf

Compromising Anonymity Using Packet Spinning Vasilis Pappas, Elias Athanasopoulos, So:ris Ioannidis and Evangelos P. Markatos ICS‐FORTH Anonymizing Systems •  Many open systems for anonymous communica:on – Freenet, TOR, I2P etc •  One of the most successful is TOR – Approximately 2500 online nodes •  Serving thousands of users Packet Spinning ‐ Vasilis Pappas ‐ FORTH 2 TOR in a nutshell •  Each node acts as a relayer •  Users create circuits over the relayers in order to communicate anonymously Packet Spinning ‐ Vasilis Pappas ‐ FORTH 3 This paper •  A new aOack to compromise TOR’s anonymity – The Packet Spinning aOack •  Based on: – Ar:ficially created circular circuits – Disabling crypto opera:ons on the malicious relayers Packet Spinning ‐ Vasilis Pappas ‐ FORTH 4 Roadmap •  TOR Introduc:on •  The Packet Spinning AOack •  Experimental Evalua:on •  Countermeasures •  Conclusions Packet Spinning ‐ Vasilis Pappas ‐ FORTH 5 TOR Introduc:on •  TOR uses Onion Rou:ng – Mul:ple layer packet encryp:on •  Three en::es – Onion Routers (relayers) – Directory Server – Clients Packet Spinning ‐ Vasilis Pappas ‐ FORTH 6 TOR – Example of opera:on Packet Spinning ‐ Vasilis Pappas ‐ FORTH 7 OR1 Alice OR2 OR3 OR5 OR4 Bob First hop created Packet Spinning ‐ Vasilis Pappas ‐ FORTH 8 OR1 Alice OR2 OR3 OR5 OR4 Bob Create Circuit is extended by one hop Packet Spinning ‐ Vasilis Pappas ‐ FORTH 9 OR1 Alice OR2 OR3 OR5 OR4 Bob Extend Create 3‐Hop circuit established Packet Spinning ‐ Vasilis Pappas ‐ FORTH 10 OR1 Alice OR2 OR3 OR5 OR4 Bob Relay Extend Create Alice begins a connec:on to Bob Packet Spinning ‐ Vasilis Pappas ‐ FORTH 11 OR1 Alice OR2 OR3 OR5 OR4 Bob Begin Anonymous connec:on established Packet Spinning ‐ Vasilis Pappas ‐ FORTH 12 OR1 Alice OR2 OR3 OR5 OR4 Bob Roadmap •  TOR Introduc:on •  The Packet Spinning A3ack •  Experimental Evalua:on •  Countermeasures •  Conclusions Packet Spinning ‐ Vasilis Pappas