Attackers hijacked 333 Tor relays to intercept SSH and email traffic

Ars Technica ·

Attackers hijacked 333 Tor exit relays for three days, redirecting SSH connections and attempting to expose email traffic. The campaign matters because Tor users who ignored a changed SSH host key warning could have handed over passwords, command histories and access to their servers.

The hijacking ran from 2 to 5 October. Investigators traced an initial breach to a reused password for a Tor management server and found the Linux backdoor Ebury on it and another server; they have not established how the attackers gained control of all the affected machines. Twelve attacker-controlled servers intercepted SSH connections, while compromised relays blocked several ports used for encrypted email but allowed unencrypted email traffic; it is unclear whether email connections were successfully downgraded.

In short

  • 333 Tor exit relays were involved in the campaign.
  • SSH connections were redirected to 12 attacker-controlled servers.
  • Investigators do not know how all affected servers were accessed.

Cybersecurity Technology

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Originally published by Ars Technica as “333 Tor exit nodes hijacked to intercept SSH traffic and retrieve plaintext email”.

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