MassBrowser: Unblocking the Censored Web for the Masses, by the Masses (NDSS 20) about bbs HOT 2 OPEN

MassBrowser was the topic of the 2020-04-30 session of the Tor anti-censorship team reading group. Meeting log. Some topics covered:

• MassBrowser is similar to Snowflake in some ways, viz. in its use of volunteer proxies and domain-fronted communication with the Operator (in Snowflake a similar component is called the broker). Client-to-Client proxying is a notable feature that doesn't have a parallel in Snowflake.
• Matching peers by their NAT characteristics is a cool idea; how does that work technically?
• Because the Client includes a browser, how do security updates work? Looks like it uses an electron-updater package.
• From personal conversation, it sounds as if Buddies were at one time web browser extensions before evolving into their current standalone form.
• MassBrowser is getting a security audit from Subgraph.
• There was some confusion about how Client-to-Client proxying interacts with content category whitelisting and the list of known-blocked sites. For a Client in China to read a Chinese news site through another Client in Iran, it seems that the Operator would need to know more than the "News" content category and the fact that the site is blocked in China; it would also need to know that the Client acting as a Buddy is located somewhere where the site is not blocked.
• The claim, in e.g. §V-B and §VII-C, that censors cannot block residential peer-to-peer connections, is still untested, as the group sees it. The collateral damage argument may have more to do with the agility of changing Buddy addresses rather than the utility of any single Buddy address (NATed or not): if the Buddies sparsely occupy a large address space, it can be hard to write a rule to block them without blocking something else important. But even the agility argument is untested (as in Snowflake): how often do Buddies/proxies actually change their address? The group outlined some research avenues for investigating this.

from bbs.

The conference page for the paper has resources from the conference presentation:

• Slides
• Video by Milad Nasr

from bbs.