AirDrop also shares your full name (seemingly the one associated with your Apple ID, not what you have set for yourself in your contacts), both by displaying it in the sharing interface on the involved devices and by attaching it as an extended attribute to uploaded files.
The latter is more serious imo, because those attributes live on your file system basically for ever, and they're preserved when transferring to another compatible file system or even when archived in a zip file. The meta-data can ride along with the files to completely unrelated systems even years after the fact. So if you AirDrop some files to your computer and then zip them up, anyone you send that zip to (a journalist, a public file-hosting site, w/e) will have your full legal name to go with them.
Even sharing your name through the interface seems questionable -- the fact that you and another person have each other's phone numbers is not necessarily an indication that you want to share your real names with each other. (Though i guess someone could usually find it out anyway if they already had your phone number.)
I reported this to Apple, but i don't think they care. Seems like it's by design.
Isn't that name editable on your Apple ID page? That name is also not part of your financial data on the iPhone (which usually involves your real name).
What do you think about editing the title to indicate AirDrop has security issues? When I clicked I thought it was going to be about what all I can share using airdrop lol
Interesting. I just read the title and assumed it was talking about security issues. Since we all know AirDrop can share files (what it was intended for), presumed this meant it's also sharing some data/privacy issues unbeknownst to us.
Looking at the article I would say the actual title presented is "Apple AirDrop shares more than files:
TU-Researchers discover significant privacy leak in Apple's file-sharing service", but that's a bit long for a HN title. I'm not sure what the policy is on using the subtitle (TU-Researchers discover significant privacy leak in Apple's file-sharing service) if it's more descriptive, but I think it would make sense in this case.
One explanation is that Apple has sat on this for 2 years, knowing this is a serious security bug. Another explanation is that they just don't think it's that serious. The article states-
> The discovered problems are rooted in Apple's use of hash functions for “obfuscating” the exchanged phone numbers and email addresses during the discovery process. However, researchers from TU Darmstadt already showed that hashing fails to provide privacy-preserving contact discovery as so-called hash values can be quickly reversed using simple techniques such as brute-force attacks.
The post that they then linked to is about how, by hashing random phone numbers, you can effectively de-anonymise users of popular messaging apps.
So you'd need to be in physical proximity to the person, and what you're getting is details like your phone number which aren't especially private anyway (they literally need to be given to people to be of any use). It's far from the dragnet-level issue facing Signal & Whatsapp and others.
I don't know, but that doesn't seem like an especially serious issue to me. It seems just like a research group trying to make some hype for themselves.
Not sure how much is required to brute force these, but AirDrop has been used in notably sensitive situations like the Hong Kong protests[1], where I’m sure anonymity was assumed.
Proximity doesn’t mean I would like to share my phone number. Seems like an unlikely attack day-to-day, but one with definite privacy and personal safety concerns.
In the old days they used to print giant books of these "phone numbers" and drop them on your neighbours porches. Odd how things that were common are now security risks.
Depends how easy this is to do on the fly. Lots of people thinking about it like it's a spy thriller. But could a creep with a laptop use it to harvest phone numbers from random school girls that they like the look of in starbucks? Not sure I would like my kids to experience this.
That's what I thought too since the AirDrop protocol, as mentioned in the article, doesn't even share any of that hashed info unless a user opens the share sheet to initiate an AirDrop transfer.
To me, that means that if I was going to attack someone using this exploit, I would need to sit there all day until someone used AirDrop to send something and then I'd need to make sure to have my attack planned out in advance so that I could then use that information to do something useful.
The chances of that actually happening to some detriment are so small, in my eyes.
> So you'd need to be in physical proximity to the person, and what you're getting is details like your phone number which aren't especially private anyway
Once you know the phone number, you would then be able to track an iOS device's location if it's in "contacts only" discoverability mode for AirDrop, right?
Details are nice. Sure, I'll take your statement that AirDrop hashes aren't as robust as they should be at face value, but I'm going to need you to provide more information. Of course, the PDFs have this, but the article would do well to better summarize.
If a brute-force requires multiple 500 watt GPUs in order to brute force in real time, I'd like to know. This is vastly different than if it can be done on a laptop's GPU.
If hashes can be cracked later offline with 100% certainty, I'd like to know, since a malicious device can just collect hashes simply by traveling around a city.
But if the brute forced hashes need to be confirmed with the other AirDrop device in real time, else you don't know which of dozens, hundreds, or thousands of results you might get, then this is mostly a non-issue.
There is no need to brute force. We can build a rainbow table with valid phone numbers, which we can use to lookup a phone number hash in real time (about 50ms on a regular desktop machine). PoC available here: https://github.com/seemoo-lab/opendrop/blob/poc-phonenumber-...
> Sure, I'll take your statement that AirDrop hashes aren't as robust as they should be at face value, but I'm going to need you to provide more information. Of course, the PDFs have this, but the article would do well to better summarize.
Does the article they published about that which they link to not provide enough details? In that news release they referenced, they say "However, the research team shows that with new and optimized attack strategies, the low entropy of phone numbers enables attackers to deduce corresponding phone numbers from cryptographic hashes within milliseconds."
I'm not sure if I'm misunderstanding what you're asking, or if you just didn't notice that they provide the info you want fairly easily and succinctly already.
Whats _multiple_? If it takes 20 high end Tesla to crack this real-time, a desktop could feasibly brute force the hashes in hours, and a laptop could do so in a day. This is good enough for targetted attacks to be practical.
The issue with phone number hashes has been known for a while. See for example this post by Project Zero[0] where they leverage the issue (search for "Enabling AWDL") to remotely activate airdrop.
The way I read it their implementation was more of a proof of concept of a better privacy preserving system that works in the same way. Rather than a separate app.
Seems like Apple completely ignored that inside a country the first three digits are guessable and the hashed string has a defined length, which makes hash cracking a lot easier.
So this appears to require brute-forcing through every possible hash to see which ones match.
How long would this take?
I mean, is the person's iPhone going to respond to all 10 billion possible domestic US phone numbers in the, what, 3-10 seconds they have their share sheet open? Not to mention the far larger space of e-mail addresses, ultimately limited by whatever the hash length is?
Unless the AirDrop protocol is permitting the validation of many millions of hashes per second (presumably requiring 100mbps+ speed), this doesn't appear to be even remotely a viable attack method in practice, no?
TL;DR: If you're using an Apple device with AirDrop, and have the share sheet open for something that would be shareable with AirDrop, a malicious device within ~30ft of you could start attempting to brute-force the hashes of contacts your device exposes to determine whether the other device is a contact.
(The contact exposure is in support of a setting for AirDrop to work with Everyone, Contacts Only, or No one.)
While it's certainly a bit concerning, it's pretty unlikely to be a practical attack, particularly since all it does is get you the user's contact list. It doesn't sound like there's any way of using it to exfiltrate other information, and though the article doesn't touch on this (that I saw) I'd be surprised if the attack was fast enough to just gulp down all your contacts in the couple of seconds most people have their share sheets open.
> I'd be surprised if the attack was fast enough to just gulp down all your contacts in the couple of seconds most people have their share sheets open.
No, with the share sheet open, the attacker can simply record the hashes of phone numbers that are being broadcasted. And then crack the hashes off-line at any time, which is easy since there are at max 999-999-9999 hashes.
"As an attacker, it is possible to learn the phone numbers and email addresses of AirDrop users – even as a complete stranger. All they require is a Wi-Fi-capable device and physical proximity to a target that initiates the discovery process by opening the sharing pane on an iOS or macOS device."
[+] [-] movablesed|5 years ago|reply
The latter is more serious imo, because those attributes live on your file system basically for ever, and they're preserved when transferring to another compatible file system or even when archived in a zip file. The meta-data can ride along with the files to completely unrelated systems even years after the fact. So if you AirDrop some files to your computer and then zip them up, anyone you send that zip to (a journalist, a public file-hosting site, w/e) will have your full legal name to go with them.
Even sharing your name through the interface seems questionable -- the fact that you and another person have each other's phone numbers is not necessarily an indication that you want to share your real names with each other. (Though i guess someone could usually find it out anyway if they already had your phone number.)
I reported this to Apple, but i don't think they care. Seems like it's by design.
[+] [-] xvector|4 years ago|reply
1. Airdrop an item to your Mac.
2. Run 'mdls [file]' to see associated metadata
3. Copy the file, run 'mdls [file]' again - open it locally or even in a macOS VM - you'll see that your name and phone name is copied with the file!
https://eforensicsmag.com/airdrop-forensics-by-kinga-kieczko...
[+] [-] hda111|5 years ago|reply
[+] [-] casualtemp|4 years ago|reply
[+] [-] auslegung|5 years ago|reply
[+] [-] heavymark|5 years ago|reply
[+] [-] kbenson|5 years ago|reply
[+] [-] throw14082020|5 years ago|reply
It lists 2 vulnerabilities: Sender Leakage and Receiver leakage. The files are not at risk, its your phone number and apple ID.
Or alternatively, Maybe rename to: Apple AirDrop reveals mobile number and email
[+] [-] the_other|5 years ago|reply
[+] [-] xeromal|5 years ago|reply
[+] [-] scotchmi_st|5 years ago|reply
> The discovered problems are rooted in Apple's use of hash functions for “obfuscating” the exchanged phone numbers and email addresses during the discovery process. However, researchers from TU Darmstadt already showed that hashing fails to provide privacy-preserving contact discovery as so-called hash values can be quickly reversed using simple techniques such as brute-force attacks.
The post that they then linked to is about how, by hashing random phone numbers, you can effectively de-anonymise users of popular messaging apps.
So you'd need to be in physical proximity to the person, and what you're getting is details like your phone number which aren't especially private anyway (they literally need to be given to people to be of any use). It's far from the dragnet-level issue facing Signal & Whatsapp and others.
I don't know, but that doesn't seem like an especially serious issue to me. It seems just like a research group trying to make some hype for themselves.
[+] [-] ryanwhitney|5 years ago|reply
Proximity doesn’t mean I would like to share my phone number. Seems like an unlikely attack day-to-day, but one with definite privacy and personal safety concerns.
1: https://qz.com/1660460/hong-kong-protesters-use-airdrop-to-b...
[+] [-] jdsully|5 years ago|reply
[+] [-] willyt|5 years ago|reply
[+] [-] dkonofalski|4 years ago|reply
To me, that means that if I was going to attack someone using this exploit, I would need to sit there all day until someone used AirDrop to send something and then I'd need to make sure to have my attack planned out in advance so that I could then use that information to do something useful.
The chances of that actually happening to some detriment are so small, in my eyes.
[+] [-] lxgr|5 years ago|reply
Once you know the phone number, you would then be able to track an iOS device's location if it's in "contacts only" discoverability mode for AirDrop, right?
[+] [-] unknown|5 years ago|reply
[deleted]
[+] [-] johnklos|5 years ago|reply
If a brute-force requires multiple 500 watt GPUs in order to brute force in real time, I'd like to know. This is vastly different than if it can be done on a laptop's GPU.
If hashes can be cracked later offline with 100% certainty, I'd like to know, since a malicious device can just collect hashes simply by traveling around a city.
But if the brute forced hashes need to be confirmed with the other AirDrop device in real time, else you don't know which of dozens, hundreds, or thousands of results you might get, then this is mostly a non-issue.
[+] [-] mstute|5 years ago|reply
[+] [-] kbenson|5 years ago|reply
Does the article they published about that which they link to not provide enough details? In that news release they referenced, they say "However, the research team shows that with new and optimized attack strategies, the low entropy of phone numbers enables attackers to deduce corresponding phone numbers from cryptographic hashes within milliseconds."
I'm not sure if I'm misunderstanding what you're asking, or if you just didn't notice that they provide the info you want fairly easily and succinctly already.
[+] [-] eptcyka|5 years ago|reply
[+] [-] ergl|5 years ago|reply
[0]: https://googleprojectzero.blogspot.com/2020/12/an-ios-zero-c...
[+] [-] bla3|5 years ago|reply
Cool. Security research is important.
> The research team developed a solution that could replace the flawed AirDrop.
Wait, what? Nobody will want to install some third-party tool over this.
[+] [-] lathiat|5 years ago|reply
[+] [-] lorenzfx|5 years ago|reply
EDIT: I just found snapdrop [1], but haven't given it a try yet.
[1] https://github.com/RobinLinus/snapdrop
[+] [-] captn3m0|5 years ago|reply
Research links:
https://hexway.io/research/apple-bleee/
https://arxiv.org/pdf/1904.10600.pdf
https://www.usenix.org/system/files/sec19fall_stute_prepub.p...
[+] [-] random5634|5 years ago|reply
Your email and phone number may be less secret than these folks claim .
But aside from this overhype interesting work.
[+] [-] guipsp|5 years ago|reply
[+] [-] bluefirebrand|5 years ago|reply
[+] [-] bionade24|5 years ago|reply
[+] [-] leifg|5 years ago|reply
[+] [-] kristofferR|5 years ago|reply
[+] [-] ProAm|5 years ago|reply
[+] [-] crazygringo|5 years ago|reply
How long would this take?
I mean, is the person's iPhone going to respond to all 10 billion possible domestic US phone numbers in the, what, 3-10 seconds they have their share sheet open? Not to mention the far larger space of e-mail addresses, ultimately limited by whatever the hash length is?
Unless the AirDrop protocol is permitting the validation of many millions of hashes per second (presumably requiring 100mbps+ speed), this doesn't appear to be even remotely a viable attack method in practice, no?
[+] [-] Someone|5 years ago|reply
- mass record all these requests
- offline, recover the phone numbers or email addresses
⇒ you know who was where, when.
[+] [-] danaris|5 years ago|reply
(The contact exposure is in support of a setting for AirDrop to work with Everyone, Contacts Only, or No one.)
While it's certainly a bit concerning, it's pretty unlikely to be a practical attack, particularly since all it does is get you the user's contact list. It doesn't sound like there's any way of using it to exfiltrate other information, and though the article doesn't touch on this (that I saw) I'd be surprised if the attack was fast enough to just gulp down all your contacts in the couple of seconds most people have their share sheets open.
[+] [-] djrogers|5 years ago|reply
It’s not even that - all it gets is the phone number associated with your personal contact card.
[+] [-] grupthink|5 years ago|reply
No, with the share sheet open, the attacker can simply record the hashes of phone numbers that are being broadcasted. And then crack the hashes off-line at any time, which is easy since there are at max 999-999-9999 hashes.
[+] [-] kuu|5 years ago|reply
[+] [-] KingOfCoders|5 years ago|reply
[+] [-] crazygringo|5 years ago|reply
Isn't analyzing severity one of the most interesting, and critical, parts of discussing a potential vulnerability?
[+] [-] anfilt|5 years ago|reply
[+] [-] e2le|5 years ago|reply
https://github.com/hexway/apple_bleee/tree/master/hash2phone
[+] [-] random5634|5 years ago|reply
[+] [-] unknown|5 years ago|reply
[deleted]
[+] [-] Black101|5 years ago|reply
[+] [-] hansel_der|5 years ago|reply
the choice is reduced to "how much information do i want my personal communicator to be leaking" (and somewhat "to whom")