Cloudflare Issue Can Leak Chat App Users' Broad Location
Cloudflare Issue Can Leak Chat App Users' Broad Location
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.
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.
Thank you for posting here!
Fun fact, you can always use timing attacks to narrow down a location.
The target sends some traffic to multiple geographic sites. Looking at the response timing of that traffic gives you a maximum radius from each site. Overlay multiple radiuses and you get a workable approximate
Great point. The range shown in the article doesn't seem to be that big of a deal for me, but I suppose it could matter for some situations.
Yet another reason to move to SimpleX chat. Signal is better than nothing but far from perfect. Besides adoption I think SXC is universally the better option.
Signal is better than nothing but far from perfect.
Signal suffer from the same meta data issue IMHO and that's really all governments care about, who is talking to whom, to make relationship maps.
If they really care, they will compromise the end point to get the content.
This. In addition to metadata tracking you mention... Encrypted messages are great, until one party is compromised. Delete chat history, use a VPN, take more precautions than just using an encrypted messaging app. For most user's purposes, this is fine, leagues better than SMS or social media conversations.