this post was submitted on 21 Jan 2025
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124
Cloudflare Issue Can Leak Chat App Users' Broad Location (www.404media.co)
submitted 1 day ago* (last edited 1 day ago) by [email protected] to c/[email protected]
35 comments fedilink hide all child comments
 

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.

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[–] [email protected] 5 points 1 day ago (1 children)

CF is DNS you could be using it a lot and never know

[–] [email protected] 5 points 1 day ago (2 children)

I have a pihole serving DNS for my local network that is configured to use unfiltered Quad9 for upstream.

[–] [email protected] 3 points 1 day ago

ok, you are certainly not a common user.

[–] [email protected] 2 points 1 day ago (2 children)

Unbound is better IMO :)

[–] [email protected] 2 points 1 day ago

Well, I'm now using pihole for blocking + unbound for recursive resolving

[–] [email protected] 2 points 1 day ago* (last edited 1 day ago) (2 children)

What are the advantages over pihole?

EDIT: https://docs.pi-hole.net/guides/dns/unbound/ this page has a good explanation

[–] [email protected] 2 points 1 day 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
[–] [email protected] 2 points 1 day ago* (last edited 1 day ago) (1 children)

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

[–] [email protected] 1 points 1 day ago (1 children)

Okay but what are the advantages of doing this?

[–] [email protected] 1 points 1 day ago (1 children)

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.

[–] [email protected] 2 points 1 day ago* (last edited 1 day ago) (1 children)

Um.... yes I understand what DNS does. Really?

I'm not trying to challenge you in any way. My disconnect in understanding is what unbound does and why I would want to use it over the built-in pihole FTLDNS. What are its advantages?

EDIT: I've answered my own question, unbound queries root name servers directly instead of using DNS providers. This is interesting. New question, what is the advantage of being my own DNS provider? Privacy from my ISP (who can just see the IPs that I am connecting to, anyway)?

[–] [email protected] 2 points 1 day ago

I wasn't trying to be short or condescending either. Just relaying what I know.

It is another layer of privacy in some cases. Could protect against poisoning of I'm not mistaken, but don't quote me.

I know for me, I prefer to self host things where I can so I can own as much of my own data as possible.