Full Writeup of the Windows GDID | Hacker News Reader

Full Writeup of the Windows GDID

github.com

91 pointstypeofhuman49 comments

For those like me who were not abreast of this issue: the FBI was able to arrest some kid who hacked/is alleged to have hacked a jewellery retailer through a VPN. They were able to track the hacker via the user's GDID, which is a stable identifier unaffected by VPN usage.

This surveillance is certainly going to expand in scope as age verification comes into widespread usage. Personally I see little legitimate use case for this telemetry. It seems only useful for the purposes of tracking users for law enforcement or targeted advertising purposes.

How did they query his GDID/PUID to make the arrest though? Does the browser have access to it during some requests? Also, if it’s stored as plaintext, what’s stopping anyone from randomizing it on machine startup?

I'm guessing Ngrok gets subpoena'd, hands over the IP who created the account, page access timestamp, etc - FBI hands over to Microsoft, finds which Windows PCs were active with a certain IP on that time period, tries to correlate other characteristics such as OS version or anything to get a single hit, and then return other IPs used by that machine and everything else they have, like SmartDefender / Edge telemetry.

> finds which Windows PCs were active with a certain IP on that time period

.. and how do they do that?

While we're on the subject of telemetry, has anyone got a GDPR orientated writeup of what's known?

Well, it's a darn good thing there is nothing like that over here on the Linux side. I'm pretty sure that if e.g. systemd attempted to generate a unique, persistent machine identifier during the installation process, it'd be shot down and patched off extremely quickly.

Linux does though?

  cat /etc/machine-id

https://www.linux.org/docs/man1/systemd-machine-id-setup.htm...

cool. we definitely needed this

Not wanting to be left out, FreeBSD has it too.

Is this sarcasm?

This isn't "tracking", this is attribution in a court. The defence can't stand there and say "That's not him/this device" when the forensics point exactly at it.

It's still tracking. Just like tracking your car movements to attribute them to you is still tracking.

To be fair, the courts in USA apparently have a different definition of tracking than all normal people do. Speaking of car movements, Flock claims this isn't tracking people based on some legalese mumbojumbo. Obviously, this and GPs claims are absolutely ridiculous if you speak English, but are apparently true in american legalese doublespeak.

How a Windows device's global ID is generated may be new info in the public sphere, but the fact that the global ID exists is not a secret. This format of device ID has been in Windows since the initial release of Windows 10 in 2015, when it was introduced as part of Windows' current telemetry subsystem. To see your device's global ID, open Windows Feedback Hub, then go to Feedback Hub Settings and look under Device Information.

What I'm more interested in is how/where the GDID is used. Imagine if e.g. Edge started sending your GDID as a header in every single web request.

In a sense it doesn't matter how the global ID is used now. The fact that it exists allows it to be used in ways like what you describe, either by a malicious (?) Microsoft itself or by a malicious third-party attacker.

I'm familiar with these global IDs because I routinely used the Windows telemetry system as part of my work on the Windows core at Microsoft. We had strong policies on how and when we could access or use data for a single device as identified by global ID.

But ultimately, these policies will have a "government or court order" exception in reality even if not in theory, just like in most other consumer software observability systems. The Windows difference is simply the breadth of data that is intentionally collected by Microsoft or can be identified by any Microsoft-controlled IDs. That difference is huge in potential impact but very small conceptually.

Are there limits on what kinds of websites can request for a visitor's global ID information?

Must a website direct the user to log into their MS account before it is able to get a hold of the user's global ID information?

As far as I know, no browser for Windows allows sites to read the computer's telemetry global ID at all.

I always assumed Chrome and Edge already did this — but sent the data to their respective masters.

Isn't every Chrome download unique?

It used to be even though the package contained an Authenticode signature, each installer stub download had a unique hash, because Windows' digital signatures allow a non-executable data area in the trailer which is not computed as part of the signed data.

There is zero technical reason to do this (generating unique binaries) aside from tracking purposes.

When IE did this at the very beginning of the internet it was a real scandal.

then verizon did it for (to?) mobile phones.

I guess these things get normalized, people might say "those jerks" and then put it out of their mind.

There are, unfortunately, a lot of abuses people will tolerate in the name of convenience, especially if those abuses aren't readily apparent and affecting them directly at the time they learn about them.

The alternative is not running any proprietary tech. This would require people to give up a lot of convenience, build their own tech stack, make tools where none exist, etc. Doable for most on this forum I'd suspect, not really feasible for the population at large so the choice is even worse for them: be spied on, or abstain from using technology all together.

Its a captive audience, and why advocating for privacy is such a difficult, losing battle. People aren't going to stop using Windows because of this, so Microsoft has no incentive to do anything differently. Same goes for Meta, Google, Apple, etc.

Even for myself, I've gotten really lazy over the years and have traded quite a bit of my computing freedoms for the Apple device ecosystem's convenience factors. And that's the trap. When even the people who understand exactly what they're giving up still choose the golden handcuffs, the market has no incentive to change.

A typical phone operator records the data your phone sends to them on their servers. They're just lucky enough to have the absolutely unique ID of your phone number. Don't confuse this with something else. Microsoft and Google don't have the authority to create an ID for your computer unless they allow me to use that ID to make calls to your computer.

AI-generated "research" once more. How can anyone call it full writeup?

As someone pointed out in the X argument comments, this is unconfirmed and most likely NOT how the actual GDID being sent to microsofts servers looks like.

1. The GDID that most closely resembles the one mentioned in the DOJ indictment of Stokes is found inside the registry key Computer\HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\IrisService\IrisActionCreatives, which starts with the "g:" prefix and is explicitly called GLOBALDEVICEID. This keys holds cached json response from microsoft servers and this is clear as night and day what value microsoft servers consider a "GDID"

2. According to the research, a Microsoft account is required. No, it's not necessary. Whether or whether you are not logged into your Microsoft device, GDID is being filled in. Did AI forget to check that?

3. How can author claim this is full writeup of GDID, when you did not verify whether the value your AI found, is the one being sent along with telemetry network requests? Author did not even verify whether he found the right thing

I also verified the value computed as suggested by the repository's creator and it is different from the value discovered inside the Iris registry key that begins with "g:".

Summary: The value author of repo claims is a GDID, is not the same value as saved on microsoft servers.

Very interesting.

Some users have been deleting the entire IrisService in the registry, it appears to also be related to the systray icons on the taskbar.

The first link is a couple years old but the second one is from a couple months ago. Apparently triggered now by the latest update kb5094126, so there may be some questionable new changes going on in this particular monkey-business department:

https://gist.github.com/JMMBA/d56923502a74b6b7196dd800fad0a8...

https://thegeekpage.com/taskbar-missing-after-sign-in-6-fixe...

"Fix 3" is the one where the IrisService reg key is nuked.

Windows GDID Changer:

https://news.ycombinator.com/item?id=48818707

> The court record itself says a reinstall produces a new GDID

That's a half truth if I ever saw one. Telemetry also includes the hardware hash (which does use SMBIOS serial number, CPUID, TPM identifiers, etc.) and that one survives OS reinstalls and even hardware swaps. It is the underlying id used for things like Autopilot (the equivalent to Apple's remote MDM lock).

one thing this doesn't touch on that I am curious about is how was browsing history, etc, correlated to the GDID?

Ya. The FBI report to the court said that Microsoft showed the GDID visited the ngrok.com/signip page while using a VPN. I would have figured at that level the OS would not know domains but likely IP addresses. So it must be browser telemetry right?

Edge history syncing, presumably.

Can promise you a re-install does nothing for your privacy. Plenty of IDs are embedded in the hardware.

Related background:

Windows telemetry used to track web activity, link VPN activity to source IP

https://news.ycombinator.com/item?id=48807767

U.S. v. Stokes https://www.justice.gov/usao-ndil/media/1450651/dl

Couple questions:

1) Do we think this is actually how the FBI found this kid or is this simply what they're saying in order to keep some other tool hidden?

2) Is there a way to block or manually change the GDID from being revealed. If it's the browser leaking it, do all browsers leak it?

Windows GDID Changer:

https://news.ycombinator.com/item?id=48818707

Complaint says "Cybersecurity researchers at Microsoft" found the kid and handed his name to FBI

So can you change/spoof your GDID easily?

Windows GDID Changer:

https://news.ycombinator.com/item?id=48818707

Wasn't this the GUID (Globally Unique Identifier) of early 00s Windows? When did it change to GDID? Are they the same?

No relation. GUID is just a format for a 128-bit unique number, used throughout the software industry. This is a specific 64-bit number assigned to your Windows device.

So another GUID, gotcha

Maybe try reading the writeup? GDID's are 64 bit for one thing, not 128 like GUIDs.

Maybe understanding nuance

Aside from the writeup, how stupid must one be to commit cybercrimes from a Windows 11 computer full of spyware?

is there a mac equivalent to the windows GDID?

Every little bit of hardware off an apple line is serialised out the wazoo, and the device's serial number is associated with every apple ID ever used to sign in to the device. I doubt it ever gets deleted. So yeah.

Gonna have to /s this one and say firstname.lastname @ icloud.com

this is why Microsoft is pushing so hard for Microsoft accounts at install

An MS account is not required for a GDID to be issued.

But without an MS accoutn it would not be connected to the browsing history

This is not true either; to Microsoft, every anonymous GDID is its own unique account on their servers.

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