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Find You: Building a stealth AirTag clone

positive.security

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Re: Find You: Building a stealth AirTag clone

#91

Post by ALittleLight »

hossbeast wrote: post #81
PragmaticPulp wrote: post #80

Earlier quoted context omitted.

> If it's the latter, it might mean that the entire AirTag product line is dead in the water. The average consumer, or even 99.9% of consumers, don't care at all. They want to find their things. AirTags help them find their things. They don't care how it works. End of story. It's not a popular opinion on HN where everyone wants to understand every technical detail of how every product works, but in the real world it…

Surely consumers also care about not being stalked / their real-time location given to third parties?

I think the problem is people have to decide "I'm not going to buy this because if nobody buys this then people won't be able to buy this and use it to stalk people." In other words, the consumer gives up a product they want in exchange for a common good they get an infinitesimal benefit from.

Re: Find You: Building a stealth AirTag clone

#92

Post by quantumduck »

gabeio wrote: post #87
Joeri wrote: post #85

Earlier quoted context omitted.

Isn’t that last scenario basically what the competitors do? The problem is not the airtag, it’s the find my network. Anything that can be tracked through the find my network can be used for malicious purposes. It is apple’s USP but also its achilles heel.

> The problem is not the airtag, it’s the find my network. Tile, for example, actually works the exact same way. If you fully loose your tile connected to your keys you can put it into a "lost" mode [1] which will then notify you and gps locate it just like an airtag if someone with the tile app is near your tile. But you are correct, the big difference here will be how many devices have tile installed vs iphones. [1…

There's literally no one I know who uses tile. On the other hand, airtag find my network will guarantee a near 100% coverage in the west and even in some Asian countries.

Re: Find You: Building a stealth AirTag clone

#93

Post by quantumduck »

bigiain wrote: post #83
542458 wrote: post #59

Earlier quoted context omitted.

I feel that if the stalker is buying dedicated stalking gear online there are “better” options - you can get actual compact GPS trackers that report over cellular for $10-20.

Not with anything like the battery life or small sizes as an AirTag. Those sort of devices are a reasonable choice for mounting in your own vehicle, where you can provide relatively unlimited power (and many of them have the ability to implement engine kill). But you aren’t going to slip one of those into someone’s pocket unobtrusively as you bump into them going past. Or attach it to their car in a car park.

More than battery life or small size, I think the most important cost is the cellular plan. With AirTag, the find my network acts as the communication backbone and it tracks the AirTag in literally every country, at no cost. On the other hand, cellular is expensive AF.

Re: Find You: Building a stealth AirTag clone

#94

Post by spoonjim »

If we had a government that had a proper relationship with corporate entities, when Apple launched AirTag the government would have been able to say "well we didn't think of that before, but that's fucked up and banned, you need to disable all AirTags and refund all customers."

Re: Find You: Building a stealth AirTag clone

#95

Post by a-dub »

adhesive_wombat wrote: post #90
a-dub wrote: post #36

silly question here: modern smartphones rotate their mac addresses frequently for privacy, but aren't the bluetooth addresses on phones and headphones and all the rest static and easily detected?

Yes, many devices use rotating keys for this exact reason (search keyword: Resolvable Random Private address).

ahh, interesting. so i'm guessing the whole privacy preserving digital contact tracing system was just capturing these randomly rotating keys (presumably with some signal strength filter and perhaps tuning of the frequency of key rotation) that were already beaconing out as part of having the bluetooth stack turned up.

cool.

Re: Find You: Building a stealth AirTag clone

#96

Post by rlt »

hossbeast wrote: post #81
PragmaticPulp wrote: post #80

Earlier quoted context omitted.

> If it's the latter, it might mean that the entire AirTag product line is dead in the water. The average consumer, or even 99.9% of consumers, don't care at all. They want to find their things. AirTags help them find their things. They don't care how it works. End of story. It's not a popular opinion on HN where everyone wants to understand every technical detail of how every product works, but in the real world it…

Surely consumers also care about not being stalked / their real-time location given to third parties?

AirTag is one of many ways you can be stalked. Perhaps it’s the cheapest or most well known method at the moment, but you can already buy GPS + cellular trackers that aren’t much more expensive or larger, and they’re only going to get better and cheaper over time.

This problem will need to be addressed though other means than a single company intentionally crippling their own product.

Re: Find You: Building a stealth AirTag clone

#97

Post by iudqnolq »

SV_BubbleTime wrote: post #88
iudqnolq wrote: post #66

Earlier quoted context omitted.

You get 37 bytes, and an optional extra 37 bytes with a more complex negotiation.

My memory is a little fuzzy, but iirc after required tags in the advertising packet you had ~28 bytes that could be tagged 0xFF - mfg data. Then there is also BLE5 which adds advertising extensions to get to 240-250bytes. And the scan response packet which was under 30 all the time. But I could be wrong about all of that, been a little while since I was that deep in BLE. Point for me is that Apple absolutely could do…

I've read a bunch of different numbers around 30, but I've never used beacons personally. I pulled out my copy of the O'Reilly book on BLE (covers up to Bluetooth 4.1), which says this

> Each advertising packet can carry up to 31 bytes of advertising data payload, along with the basic header information (including Bluetooth device address).

I didn't know about advertising extensions, thanks for the info. Without that I'm not sure if supply chain verification is feasible? I also wonder if there's a significant battery impact to broadcasting more data. I suppose they could overload the device address uuid?

Re: Find You: Building a stealth AirTag clone

#98

Post by mmastrac »

bombcar wrote: post #84
dwaite wrote: post #82

Earlier quoted context omitted.

Yes, you could do attestation schemes for hardware - such as a single manufacturing-time private key for large batches (say 1M+ AirTags) or something like Direct Anonymous Attestation. Apple likely would go toward batch keys - in addition to being simpler crypto, it doesn't give them the capability to use other mechanisms to potentially correlate location reports. That said, AirTags work solely within BLE advertiseme…

Perfect! The last bit can be used to indicate a valid key. ;)

They could repurpose the evil bit! ;)

Re: Find You: Building a stealth AirTag clone

#99

Post by cryptonector »

> I find it quite funny how they promote having tracking alerts for a tracking system that they have brought to life in the first place. They introduced the first-ever system for easy, cheap, worldwide tracking into a world where “unwanted tracking has long been a societal problem”, applaud themselves for implementing broken anti-stalking features, and now coerce others into also implementing protection against the tracking network they have rolled out.

It's almost like it's on purpose.

Imagine building a tracking system where your only way to avoid being a victim is to have everyone agree to not participate.

Re: Find You: Building a stealth AirTag clone

#100

Post by cryptonector »

PragmaticPulp wrote: post #80
mmastrac wrote: post #16

Does this mean that Apple is failing to validate the capability of things that purport to be AirTags? Or that the BLE protocol is just not powerful enough to have Apple signatures on each broadcast public key? If it's the latter, it might mean that the entire AirTag product line is dead in the water.

> If it's the latter, it might mean that the entire AirTag product line is dead in the water. The average consumer, or even 99.9% of consumers, don't care at all. They want to find their things. AirTags help them find their things. They don't care how it works. End of story. It's not a popular opinion on HN where everyone wants to understand every technical detail of how every product works, but in the real world it…

The average consumer also doesn't want to be stalked, have their cars stolen, etc.
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