Hi Tor,
I am reaching out to inform you of an upcoming news story concerning a potential deanonymization attack on Onion Services.
What is happening?
On September 9, 2024, The Tor Project received a press inquiry from Norddeutscher Rundfunk (NDR, part of ARD, a German public broadcaster) with a request for comment to their upcoming reporting of "investigative measures by German and international law enforcement agencies in the Tor network, in particular the localisation and deanonymisation of onion services." We complied with the outlet's deadline of September 12th and answered a series of questions.
The reporter claims to have "evidence that shows that in several cases German law enforcement authorities were able to locate the Tor entry node of onion services and thus successfully deanonymise Tor users. V2 and V3 onion addresses were affected at least between Q3/2019 and Q2/2021." The reporter further claims that "law enforcement agencies used so-called timing analyses and broad and long-term monitoring of Tor nodes in data centres."
As of today, The Tor Project has not been granted access to supporting documents, and has not been able to independently verify if this claim is true, if the attack took place, how it was carried out, and who was involved.
In the absence of facts, it is hard for us to issue any official guidance or responsible disclosures to the Tor community, relay operators, and users at this time.
We are calling for more information from you.
If you have any information that can help us learn more about this alleged attack, please email security@torproject.org.
If you want to encrypt your mail, you can get the OpenPGP public key for this address from keys.openpgp.org. Fingerprint: 835B 4E04 F6F7 4211 04C4 751A 3EF9 EF99 6604 DE41
Your assistance will help all of us take the necessary steps and precautions to keep Onion Services safe for the millions of users that rely on the protections Tor provides.
Are Tor users safe?
Tor users can continue to use Tor Browser to access the web securely and anonymously. Nothing that the Tor Project has learned about this incident suggests that Tor Browser was attacked or exploited. We encourage Tor Browser users and relay operators to keep software versions up to date.
The reporter's questions focus on the use of onion services and .onion addresses. Which leads us to assume that the alleged attack was targeting a specific .onion site.
We will continue to share updates on this email as this situation evolves.
Thank you!
Isabela