On 1/9/23 09:11, Christian Pietsch wrote:
On Mon, Jan 09, 2023 at 01:31:52PM +0000, EfraimVagner via tor-dev wrote:
Anyone knows how he did it? Seems kind of wierd he says he is against
oppressive regiments but doesn't give any useful information about what the
issue is.
The Snowflake proxies might have been detected using the method described in
this publication. The link was postet to anti-censorship-t...@lists.tpo on
Saturday.
URL: https://www.mdpi.com/2076-3417/13/1/622/pdf
Title: F-ACCUMUL: A Protocol Fingerprint and Accumulative Payload Length
Sample-Based Tor-Snowflake Traffic-Identifying Framework
Authors: Junqiang Chen, Guang Cheng, and Hantao Mei
Abstract: Tor is widely used to protect users’ privacy, which is the most
popular anonymous tool. Tor introduces multiple pluggable transports (PT) to
help users avoid censorship. A number of traffic analysis methods have been
devoted to de-anonymize these PT. Snowflake is the latest PT based on the
WebRTC protocol and DTLS encryption protocol for peer-to-peer communication,
differing from other PT, which defeat these traffic analysis methods. In this
paper, we propose a Snowflake traffic identification framework, which can
identify whether the user is accessing Tor and which hidden service he is
visiting. Rule matching and DTLS handshake fingerprint features are utilized to
classify Snowflake traffic. The linear interpolation of the accumulative
payload length of the first n messages in the DTLS data transmission phase as
additional features are extracted to identify the hidden service. The
experimental results show that our identification framework F-ACCUMUL can
effectively identify Tor-Snowflake traffic and Tor-Snowflake hidden
service traffic
It is extremely unlikely that whoever posted those snowflake IPs
publicly did so as a passive traffic observer. There are easier ways to
discover snowflake IP addresses, and I don't get the sense that the
owner of that Github repository has an AS-level vantage point that
they're using to DPI real snowflake traffic.
On Thu, Jan 05, 2023 at 07:31:31AM -0500, t...@nullvoid.me wrote:
https://github.com/scriptzteam/Tor-Bridges-Collector
Seems an attacker has found a way to enumerate ~300000 snowflakes and many
bridges. I couldn't find any discussion about this in the archive.
This was brought to some of our attention a while ago. Whoever it is,
they have a massive misunderstanding of responsible disclosure and
research ethics, and also a misunderstanding of how snowflake fits in
the censorship circumvention space. My guess is they are doing nothing
more complicated than running a snowflake client and logging the IPs of
proxies that they get assigned to. Anyone can do this, it's not a bug,
it's just part of how Snowflake works: you can see the IPs that your own
machine is connecting to. We have mitigations to prevent full IP address
enumeration in the pipeline, but one of Snowflake's strengths is that
these IPs are behind NATs, and there is daily churn in the addresses
available. Over time, any one client will be able to generate a large
list of IPs, but the goal is to create enough of a moving target that
enumeration is not worthwhile or complete.
The owners of this repository never reached out to us: we learned about
it indirectly. They are only doing harm by publishing this information.
They are not telling us anything new nor helping improve the resilience
of Snowflake to these kind of enumeration attacks in any way. I'm not
sure how they expected this to help at all.
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