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What an attacker gets from Apple devices if they sniff Bluetooth traffic
- vdnkh 7y agoClickbait title: 'If Bluetooth is ON on your Apple device everyone nearby can understand current status of your device, get info about battery, device name, Wi-Fi status, buffer availability, OS version and even get your mobile phone number'
- snarf21 7y agoAgreed. It is weird that they just hash the phone number and don't salt it with something else. Even just appleid+phonenumber would be huge and prevent pre-attacks.
- aidenn0 7y agoIt's what about an hour to calculate the SHA of all 10 digit numbers in the US?
- bristleworm 7y agoI was curious: my Laptop needed 18 minutes.
- aidenn0 7y agohaha, I checked my source and I had the units wrong so I was off by a factor of 1000. Looks like 8x GTX1080s can do almost 3 billion SHA256 hashes per second, so you could just brute force these with no table with the right hardware.
- Operyl 7y agoThen the problem is: “You’re leaking your Apple ID to everyone in your contact list!” or more, depending on how exactly they’d plan to distribute Apple IDs to everybody else. The hash of the phone number thing is to provide the “contacts only” airdrop thing.
- snarf21 7y agoI'm missing what you are saying, sorry. If I know your email already, nothing is getting leaked. If I don't know your apple ID email, I have to brute force all combinations of email concatenated with your phone number to figure it out. If a stranger doesn't know either piece, they'd have to pre-image the entire space which is nigh impossible (all phone #s X all email addresses)
- wool_gather 7y agoYou're right, but they probably have/want to cover the case where you've given someone just your phone number (or just your email).
- Operyl 7y agoIt’s convenient to just have a phone number be the piece both sides know. It’s not as magical if you need to also give your AppleID to every single contact manually, and if you have some sort of Phone Number to AppleID lookup service it’d be abused just as badly is what I’m saying here.
- thedanbob 7y agoAnd for the phone number part, “If Bluetooth is ON on your Apple device AND you’re trying to Airdrop something (which you’d expect to send some identifying information) or connect to a new WiFi network (same)...” To be fair I wouldn’t necessarily expect those actions to send out a hash of my phone number, but the threat indicated by the title is definitely overblown.
- eridius 7y agoAirDrop has to send out a hash of you so that way the surrounding devices that are set to "contacts only" can use it to determine if you're in their contacts list (and therefore that it should respond). I'm not sure why WiFi has to send a hash of your phone number, I thought it just prompted nearby devices to ask if they wanted to share it. Maybe there is some functionality there relating to determining if the sender is in your address book, I'm not sure.
- ilikehurdles 7y agoA part of the problem is that bluetooth is almost always ON on iPhones. The way one typically toggles it from the control center only disables bluetooth for a short period of time (24 hours), after that, it turns on again. One has to go into settings to actually disable bluetooth.
- deleted 7y ago[deleted]
- justwalt 7y agoGotta love the dark pattern. I remember when they made the change, I was pretty frustrated with that.
- millstone 7y ago"Dark pattern" seems too strong. Apple doesn't benefit from your turning Bluetooth on and isn't trying to manipulate you into doing so. It's fixing the annoying issue of today's AirPods failing because of something I did yesterday afternoon which I forgot.
- m463 7y agoApple does benefit from turning bluetooth on. Your phone will locate and report bluetooth ibeacons, and allow apple to update their crowdsourced location databases. The same thing with wifi (which has the same behavior in control panel) It would have been SO SIMPLE to have a nicer pattern. short press to disconnect, long press to turn off.
- ilikehurdles 7y ago>It would have been SO SIMPLE to have a nicer pattern. short press to disconnect, long press to turn off. Indeed, this is exactly what I expected would happen when I long pressed and I was disappointed when it didn’t. There are definitely times like this when Apple’s UX gets more credit than it deserves.
- 7y ago
- mehrdadn 7y agoIs this true on Android too? Can someone just lift your phone number via you merely having your Bluetooth/Wi-Fi/etc. running?
- bri3d 7y agoFirst off, "someone can lift your phone number via you merely having Bluetooth running" is entirely not true of this information leak. The scope of this issue is that an unsalted SHA256 of your phone number is broadcast when you open the Share dialog with AirDrop and Bluetooth active. Your phone number is broadcast to determine whether the sending device is in the receiving device's contacts list. The feature that causes this information leak (AirDrop) has no equivalent on stock Android, but hundreds of horrifyingly insecure apps exist to replicate it. Google are introducing a similar feature (Fast Share) soon and we will see how it fares security wise. This is an interesting cryptography question: how do you allow two mutually untrusted client devices to determine that they share a common secret, without disclosing the secret? And for bonus points, how do you allow this to happen without two-way communication?
- nemosaltat 7y ago>This is an interesting cryptography question Is that a solved problem?
- mehrdadn 7y agoIt sounds impossible for very-low-entropy secrets. Like just imagine if the secret is 1 bit. Anyone can pretend they have that 1 bit (since they can just try both possibilities), which would let them determine that's the same secret the other person has. The only solution would seem to be to stretch the entropy and make a brute-force enumeration slow.
- Thorrez 7y ago> how do you allow two mutually untrusted client devices to determine that they share a common secret, without disclosing the secret? Use a PAKE. Although I think they all require two-way communication. https://en.wikipedia.org/wiki/Password-authenticated_key_agreement https://en.wikipedia.org/wiki/Password-authenticated_key_agr...
- groovybits 7y agoThis article fails to mention that AirDrop is only enabled for Contacts by default. Furthermore, each AirDrop session is a TLS session, where the users exchange iCloud certificates to authenticate each other. See: https://www.apple.com/business/site/docs/iOS_Security_Guide.pdf https://www.apple.com/business/site/docs/iOS_Security_Guide.... (p. 45) The phone is only as secure as the user makes it.
- bri3d 7y agoI believe that this information leak occurs BECAUSE AirDrop is only enabled for Contacts by default - you disclose your own hashed phone number when you open the Share dialog in order to allow nearby phones to decide whether you're on their Contacts list.
- randyrand 7y agoThat doesn't make sense. It's whether they are in my contact list. If visibility is set to everyone then your phone will identify itself using its phone number so people know which device is yours and can click to share with it.
- kube-system 7y agoDoesn't the statement go both ways? How do you tell that a remote phone is in your contact list?
- groovybits 7y agoThe claimed threat vector is loss of anonyminity. There is no anonyminity designed into AirDrop, and nowhere in Apple's documentation do I see the claim for it. You iCloud account is your identity. When you choose to share things directly from your phone, you are choosing to share that identity. How else can another iPhone verify you? There is no information leak. This is a clickbait title combined with a 'Well, duh' moment.
- bri3d 7y ago
- phenomax 7y agoAre there any news from Apple's side?
- bri3d 7y agoHere's the problem space - I'm interested in how HN would design AirDrop without this information leak: How do you allow two mutually untrusted client devices to determine that they share a common 9-digit number, without disclosing the secret? And for bonus points, how do you allow this to happen without two-way communication or access to a central authority?
- drewbug 7y agohttps://en.wikipedia.org/wiki/Socialist_millionaires https://en.wikipedia.org/wiki/Socialist_millionaires ?
- zokier 7y agoSend nonce+hash(phonenumber+nonce)? Then recipient could just iterate over contacts and check if they get same hash for anyone. Expensive but works? OR send (handshake) message encrypted with recipients phone number (put through KDF). Anyone knowing the recipient probably could be able to get your phone number, but that seems like an improvement?
- bri3d 7y agoThe first approach protects against a global lookup table attack but doesn’t help with the root issue that a 10 digit phone number isn’t enough entropy and you could still brute force the number (depending on the hash algorithm) in seconds to hours. The second approach isn’t how AirDrop works as a product: when you open the Share dialog, you see a list of eligible recipients (either people with open permissions OR you in their contacts list). The recipient is the one doing the identity check, so their phone number isn’t known upfront.
- stordoff 7y agoI'm unfamiliar with AirDrop, but is there any reason it _has_ to work with phone numbers? Would sending nonce+hash(AppleID+nonce) work? I suspect an email address would have significantly more entropy than a phone number (36^6 * 4 ~= 10^10, so six alphanumerics plus four common email domains has about the same entropy (assuming random distribution-you could make better guesses)). One downside is that it may be make targeted attacks easier (if you can guess the approximate form of someone's email address, you can easily confirm it), but that doesn't seem like much of a leak if you can already guess sufficiently closely. Sending hash(nonce+AppleID+phone number) might be an option, but that feels more limiting.
- DevKoala 7y agoThe title is a lie. Checking the status of your phone or collecting your phone number is much different of collecting information for “what happens on your iPhone”. I am downvoting this.
- buboard 7y agoMAybe the IT community should be telling people the truth: smartphones are terminals to the worldwide network of hackers. There should be no expectation of real privacy. Encryption can temporarily obscure data, until it becomes obsolete.
- lukifer 7y agoThe legal frameworks surrounding privacy all revolve heavily around "reasonable expectations of privacy". I can't be upset if someone learns salacious information from the street through an open window; but if I close the blinds and someone intentionally peeks through a crack, they are violating my expectation of privacy and potentially breaking a law, even though I failed to secure that privacy properly by covering every square inch of the window. In some cases, it can be possible to use E2E encryption to create a secret that is functionally impossible to discover. But even in cases where digital security is flawed, vulnerable, or outsourced to a third party, it's still valuable to us from a legal standpoint to maintain social expectations of privacy.
- _bxg1 7y agoI mean, fair enough. But all of these are highly local (and most require user interaction), meaning they're less of a privacy concern and more of a security concern for high-value targets. Localized phishing, mostly. Plus you can guard against them by turning off bluetooth. Worth knowing about if you're somebody important, or manage security for someone who is, but pretty far from "Everyone Knows What Happens on Your iPhone".
- dlivingston 7y agoThe edge case would be a someone using these techniques on, say, an attractive woman three seats down on the train. In addition, one (hypothetically) could use iOS state awareness in conjunction with other attack vectors to gain access: i.e., we have an attack vector to gain remote access, but it only works if the target device is unlocked.
- PaulMest 7y agoAny idea why this is flagged? I found the demos and the GitHub repo pretty interesting.
- bri3d 7y agoI didn’t flag but it’s obvious why: the title and introduction paragraph is comically misleading. Without the hyperbole it would be an interesting discovery, with the hyperbole it’s obnoxious fear mongering.
- zeveb 7y ago> Any idea why this is flagged? In my experience, anti-Apple sentiment tends to get either downvoted/flagged to oblivion or upvoted through the stratosphere. I suspect it's due to Apple being a particularly polarising firm: those who like it, love it, while those who dislike it, loathe it.
- est31 7y agoIt got flagged for the title I think: https://news.ycombinator.com/item?id=20529383 https://news.ycombinator.com/item?id=20529383 Few hours later after flagging an admin has changed the title to the current one and un-flagged it. I just copy-pasted the title from the original one in the submisison without thinking much about it. In retrospect, the new title is much better. Also as another commenter hinted, Apple has some very loyal fans.
- newscracker 7y agoThe constant stream of information broadcast on Bluetooth is a concern. But MAC addresses of Apple devices have been randomized for a long time. The device name is something that could be used as a fingerprint for a longer duration if it turns out to be unique. What are the other risks, from a tracking perspective, from this general information broadcast?
- hansdieter1337 7y agomd5 of a 10 digit phone number... classic noob mistake.
- aloer 7y agotechnical problems aside it’s not great to see how many people around us leave leave AirDrop on for everyone. Sitting in a train or plane full of people means there’s usually 3-4 at least in range to randomly annoy with shared pictures or to force open a link in safari works as intended I guess sidenote: anyone know what limits there are on all things short range wireless? How many AirPods can reasonably work in a small area? How many Apple watches can unlock a mac wirelessly? How much AirDrop/short range device discovery can happen simultaneously?
- vegardx 7y agoOn some morning flights I'd bet that close to half of the passengers are using some type of wireless noise cancelling headphones, and I have yet to notice any problems. So the bandwidth or noise doesn't seem to be an issue.