A security researcher made a tool that let them quickly check which of Cloudflare's data centers had cached an image, which allowed them to figure out what city a Discord, Signal, or Twitter/X user might be in.

cross-posted from: https://lemmy.ca/post/37638868 [email protected]

This affects Signal too

An issue with Cloudflare allows an attacker to find which Cloudflare data center a messaging app used to cache an image, meaning an attacker can obtain the approximate location of Signal, Discord, Twitter/X, and likely other chat app users. In some cases an attacker only needs to send an image across the app, with the target not clicking it, to obtain their location.

https://gist.github.com/hackermondev/45a3cdfa52246f1d1201c1e8cdef6117?ref=404media.co

Signal, an open-source encrypted messaging service, is widely used by journalists and activists for its privacy features. Internally, the app utilizes two CDNs for serving content: cdn.signal.org (powered by CloudFront) for profile avatars and cdn2.signal.org (powered by Cloudflare) for message attachments.

    • theunknownmuncher@lemmy.worldEnglish
      172·
      1 day ago

      I support this because most all cloudflare websites require browser fingerprinting otherwise they will not serve you the page. The moment I enable the jShelter addon, I am cut off from a significant portion of the internet

              • melroy@kbin.melroy.org
                31·
                23 hours ago

                So Unbound is actually a very powerful validating, recursive and caching DNS resolver. So without relaying on Google DNS or ISP DNS, you can host your own Unbound recursive DNS server, which can do request to other DNS servers and even root-dns servers. You can even setup your own stub zones and forward zones (sorry this is too much details I know). And like I said it also has caching feature. I will soon create a blog post about Unbound as well on my https://blog.melroy.org site be sure to subscribe.

                Here is a snipped of part of my config, feel free to use it however you want:

                        # Serve stale data
        serve-expired: yes
        serve-expired-ttl: 86400           # one day, in seconds
        serve-expired-client-timeout: 500  # 500ms

        # Increase caches for better performance
        msg-cache-slabs: 4
        rrset-cache-slabs: 4
        infra-cache-slabs: 4
        key-cache-slabs: 4

        rrset-cache-size: 300m
        msg-cache-size: 150m

        outgoing-range: 200
        num-queries-per-thread: 100
              • Hellmo_luciferrari@lemm.eeEnglish
                2·
                24 hours ago

                You can use both. Unbound is a validating, recursive, caching DNS resolver.

                You can setup Unbound to be a self hosted DNS solution, and point PiHole to use your Unbound.

                Source: Unbound

                  • Hellmo_luciferrari@lemm.eeEnglish
                    1·
                    24 hours ago

                    Do you know what DNS does?

                    If you don’t, essentially is what translates IP addresses to hostnames.

                    So what having unbound would do is allow you to do DNS lookup locally.

    • melroy@kbin.melroy.org
      122·
      1 day ago

      Fully agreed, sorry to see people down voting you. But the Internet was not meant to be run by a single company called Cloudflare, it’s a dangerous prospective. Since the more people depend on Cloudflare the more powerful it become and the more depend people will become. We need alternative solutions to protect against DoS and more.