this post was submitted on 23 Jan 2025
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Was posted yesterday to a lot of communities, it's very clickbait:
So it's a bit rough... In Europe it means basically which country the target is in. Also cloudflare servers are not evenly distributed in the world, so resolution can differ wildly worldwide.
So it's not really zero click.
Sounds interesting though, nice writeup, but not as scary as it sounds from the title.
The vulnerable app can be anything that displays an attached image though. And a 250-mile radius compared to the whole world is still a very significant step for governments trying to track down dissidents, etc.
The section on responses by Cloudflare, Signal and Discord is disappointing. They're not taking it seriously enough.
Did you keep reading after the intro?
Excerpt:
If the target has push notifications enabled (which it is by default), they don't even have to open the Signal conversation for their device to download the attachment. Once the push notification is sent to their device, it automatically downloads the image from Signal's CDN triggering the local datacenter to cache the response.
An attacker can run this deanonymization attack any time and grab a user's current location without a single interaction.
If it's still only the datacenter it doesnt matter that much.
And with SS7 they can get even more precise location, and you can't really hide from that if you want to use a phone with a phone number, what is the point. This is an interesting way of attack, noone really thought about this before, but it's not "oh-my-god everyone can be tracked via signal". I guess the closest server doesn't even selected via geographical distance, but much more depends on network infrastructure of your location, so Google Maps API can't really help here.
And again any VPN could defend against this, so if you want to hide which country you are in currently, it should be the 0th step to use a VPN.
Does everyone have access to tracking which stations send the phone signal in the SS7 network?
Yes, anyone can buy access.
Cloudflare has more servers in Europe than in North America. That does trace you to which country, which IMO is pretty significant. Especially with the GeoGuesser "average the circles" thing he coded.
The user having to have the vulnerable app installed does not make it not zero click.
Yeah, this sensational as a headline. It's a clever idea that is not simple, requires an already compromised device and user, and won't work except very specific conditions.
""compromised device"" in this scenario is any device with a chat app installed, push notifications on, and the chat service uses Cloudflare CDN. This is a very common setup, Discord and Signal were mentioned as examples. Many others are vulnerable for the same thing. With read receipts on the chat platform (like Signal), no push notifications are required.
The headline is sensationalist, but it isn't something to be ignored. Especially for more privacy focused platforms like Signal, even leaking the country someone is in can be considered a risk. That's effectively what this attack allows.
I feel like people here have forgotten the difference between "vulnerable" and "compromised".
It matters because calling everyone's default setup chat apps compromised implies that an attack has occurred.
Already addressed in a different comment, but yes.
It doesn't require them to have a compromised device. If they have Signal, or something similar, you just need to message them with an image attachment, then get to work checking where that image got cached.
Not at all.
Any of these being different would not make this possible for a number of reasons. The author is talking about journalists and security minded people being at risk, but it's hard to imagine anyone going above the defaults to protect would be at much risk if they didn't take one or two of these steps as protection.
I assume from your comment you're thinking "compromised device" to mean attacked, and those are synonymous. It's just a phone with no protections.
That's not a compromised device though, it's a device with default settings.
Yes, which is a compromised device. A Windows machine without any antivirus or malware protection is a compromised device, for example.
Read the back half of this writeup and realize the target audience should be people with basic security steps taken. No journalist going out of their way to talk to whistleblowers is going to have a default settings phone, or any phone on them at all for that matter I would expect.
Wouldn't it be a vulnerable device? Up until the point it's compromised by downloading a malicious image?
Windows machines have default antivirus. I would not expect disabling push notifications to be a basic security measure. Pretty much everyone has push notifications, including the target audience. A lot of them also don't take a device-wide VPN because they expect only websites to track them.
The user profile picture is not an attachment.