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Hash collision in Apple NeuralHash model

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Re: Hash collision in Apple NeuralHash model

#351

Post by snowwrestler »

ethbr0 wrote: post #248
sandworm101 wrote: post #201

Earlier quoted context omitted.

>> there is no law who requires them to "scan" on device. There is. Apple must comply with warrant requests. If they have a system for scanning files on customer devices they must, if presented with a warrant, allow police access to that system. We can quibble about jurisdictions and constitutional protections, but if the FBI shows up with a federal warrant demanding that Apple remotely scan Sandworm101's phone for a…

That's an incomplete statement. Currently, they must comply with warranty requests by scanning if they have the ability to scan . If they have no such ability (say, because they designed their phones from a privacy-first perspective), the law makes no requirement that they create such a capability. And that's what pisses people off about this.

If Apple launches a system for comparing iCloud uploads to a third-party hash list, then adding the ability to do targeted scans for arbitrary additional law-enforcement-provided hashes would also be a form of creating capability.

The people getting pissed off about this have not, so far as I’ve seen, demonstrated why the law would require Apple to add the capability for targeted scans of arbitrary hashes.

Police can use a warrant to ask you for a video file they suspect you have. They can’t use a warrant to force you to videotape someone—even if you already own a video camera. The same principle applies to Apple.

Re: Hash collision in Apple NeuralHash model

#352

Post by jtmarl1n »

dylan604 wrote: post #232
Grustaf wrote: post #204

Earlier quoted context omitted.

Do you think Apple might perhaps halt the system if the script get wide publication?

I've only seen Apple admit defeat once, and that was regarding the trashcan MacPro. Otherwise, it's "you're holding it wrong" type of victim blaming as they quietly revise the issue on the next version. Can anyone else think of times where Apple has admitted to something bad on their end and then reversed/walked away from whatever it was?

The Apple AirPower mat comes to mind although there are rumors they haven't abandoned the effort completely. Butterfly keyboard seems to finally be acknowledged as a bad idea and took several years to get there.

The next Macbook refresh will be interesting as there are rumors they are bring back several I/O ports that were removed when switching to all USB-C.

I agree with your overall point, just some things that came to mind when reading your question.

Re: Hash collision in Apple NeuralHash model

#353

Post by bo1024 »

magpi3 wrote: post #155
bo1024 wrote: post #152

Earlier quoted context omitted.

Not complete answers but background: apple’s system works by having your device create a hash of each image you have. The hash (a short hexadecimal string) is compared to a list of known CP image hashes, and if it matches, then your image is uploaded to Apple for further investigation. A devastating scenario for such a system is if an attacker knows how to look at a hash and generate some image that matches the hash,…

But how would the attacker get the generated image on a person's phone?

I didn't mean to suggest a targeted attack. If the goal is to just overwhelm Apple's system, the attacker doesn't need to target a particular phone, they just need to distribute lots of colliding images to some phones. Even their own phones, since the colliding images wouldn't be illegal.

Re: Hash collision in Apple NeuralHash model

#354

Post by short_sells_poo »

JKCalhoun wrote: post #332
fsloth wrote: post #70

Earlier quoted context omitted.

"How can you use it for targeted attacks?" Just insert a known CSAM image on target's device. Done. I presume this could be used against a rival political party to ruin their reputation - insert bunch of CSAM images on their devices. "Party X is revealed as an abuse ring". This goes oh-so-very-nicely with Qanon conspiracy theories which even don't require any evidence to propagate widely. Wait for Apple to find the i…

> Just insert a known CSAM image on target's device. Or maybe thirty. You have to surpass the threshold. Also, if Twitter, Google, Microsoft are already deploying CSAM scanning in their services .... why are we not hearing about all the "swatting"?

Who cares that Bad Company XYZ already well known for not caring about customer privacy does it? Wouldn't you want to push back against even more increasing surveillance? Apply was beating the drum of privacy while it was convenient, wouldn't you want to hold their feet to the fire now that they seemed to do a U-turn?

Re: Hash collision in Apple NeuralHash model

#355

Post by [deleted] »

[deleted] wrote: post #252
sandworm101 wrote: post #201

Earlier quoted context omitted.

>> there is no law who requires them to "scan" on device. There is. Apple must comply with warrant requests. If they have a system for scanning files on customer devices they must, if presented with a warrant, allow police access to that system. We can quibble about jurisdictions and constitutional protections, but if the FBI shows up with a federal warrant demanding that Apple remotely scan Sandworm101's phone for a…

[deleted]

[deleted]

Re: Hash collision in Apple NeuralHash model

#356

Post by bo1024 »

rollinggoron wrote: post #293
bo1024 wrote: post #152

Earlier quoted context omitted.

Not complete answers but background: apple’s system works by having your device create a hash of each image you have. The hash (a short hexadecimal string) is compared to a list of known CP image hashes, and if it matches, then your image is uploaded to Apple for further investigation. A devastating scenario for such a system is if an attacker knows how to look at a hash and generate some image that matches the hash,…

But how does this exact attack and scenario not also apply to Google, Facebook, Microsoft etc... who are also doing the same thing on their clouds servers?

I don't know what those companies do, hopefully someone who does know will chime in and answer.

Re: Hash collision in Apple NeuralHash model

#357

Post by floatingatoll »

Grustaf wrote: post #200
nbzso wrote: post #106

Earlier quoted context omitted.

Don't feel bad at all. I dumped macOS entirely from production workflow. I cannot work on computer knowing that something is "scanning" me and I am glad that my "paranoid" feeling stopped me to upgrade all office macs. Billionaires at (Apple) don't give a flying f*ck about users privacy. It is all vertical integration in the name of world domination. How removed from reality they are. This is week after Pegasus/NSO a…

How likely is it that you will have enough colliding images in your photo library to even trigger a review? I'm guessing you need at least 5 images, perhaps much more, to trigger it. In any case, 1 image is definitely not enough.

I saw 30 mentioned somewhere, and I think that’s a more likely guess than 5. When men have a porn collection, it rarely has less than a hundred images, and so the threshold for CSAM detections can be set quite high in quantity, and enjoy a near-zero false positive rate aside from malicious hackers.

(And yes, 90% of CSAM abusers are men, so y’all will have to find some other way to weaken my argument.)

Re: Hash collision in Apple NeuralHash model

#358

Post by falcolas »

robertoandred wrote: post #335
mannerheim wrote: post #184

Earlier quoted context omitted.

You don't need to do that, just use images that collide with the hashes.

How will you know something collides?

Because the algorithm and list will be on your phone, and can (has, per TFA) be extracted.

Re: Hash collision in Apple NeuralHash model

#359

Post by falcolas »

floatingatoll wrote: post #291
shapefrog wrote: post #120

Earlier quoted context omitted.

I have seen it suggested that everyone should flood the system with flagged images to overwhelm it in protest to this move by apple. Sounds pretty stupid to me to fill your phone with kiddie porn in protest, but you do you internet people.

It’s incredibly stupid because your Apple ID will get terminated for abusing Apple services.

There are applications which automatically save images sent to you to your camera roll (such as Whatsapp, IIRC). How can Apple prove you put them there intentionally?

Granted, they most likely won't care, but it's a legitimate attack vector.

Re: Hash collision in Apple NeuralHash model

#360

Post by robertoandred »

falcolas wrote: post #358
robertoandred wrote: post #335

Earlier quoted context omitted.

How will you know something collides?

Because the algorithm and list will be on your phone, and can (has, per TFA) be extracted.

You cannot extract or reverse the CSAM hashes. They've been encrypted and blinded using server-side-only keys. If TFA said that, it's lying.
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