6 ms·
But you can essentially perform DoS attack to human checkers, effectively rendering the entire system grind to a halt. The entire system is too reliant on the p
by lifthrasiir 5y ago
But you can essentially perform DoS attack to human checkers, effectively rendering the entire system grind to a halt. The entire system is too reliant on the performance of NeuralHash which can be defaced in many ways. [1]
(Added later:) I should note that the DoS attack is only possible with the preimage attack and not the second preimage attack as the issue seemingly suggests, because you need the original CSAM to perform the second preimage attack. But given the second preimage attack is this easy, I don't have any hope for the preimage resistance anyway.
(Added much later:) And I realized that Apple did think of this possibility and only stores blinded hashes in the device, so the preimage attack doesn't really work as is. But it seems that the hash output is only 96 bits long according to the repository, so this attack might still be possible albeit with much higher computational cost.
[1] To be fair, I don't think that Apple's claim of 1/1,000,000,000,000 false positive rate refers to that of the algorithm. Apple probably tweaked the threshold for manual checking to match that target rate, knowing NeuralHash's false positive rate under the normal circumstances. Of course we know that there is no such thing like the normal circumstances.
- shapefrog 5y agoI 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.
- mannerheim 5y agoYou don't need to do that, just use images that collide with the hashes.
- deleted 5y ago[deleted]
- deleted 5y ago[deleted]
- robertoandred 5y agoHow will you know something collides?
- falcolas 5y agoBecause the algorithm and list will be on your phone, and can (has, per TFA) be extracted.
- robertoandred 5y agoYou 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.
- falcolas 5y agoOne does not need to reverse the CSAM hashes to find a collision with a hash. If the evaluation is being done on the phone, including identifying a hash match, the hashes must also be on the phone.
- mannerheim 5y agoI believe the hash comparisons are made on Apple's end. Then the only way to get hashes will be a data breach on Apple's end (unlikely but not impossible) or generating it from known CSAM material.
- falcolas 5y agoThat's not what Apple's plans state. The comparisons are done on phone, and are only escalated to Apple if there are more than N hash matches, at which point they are supposedly reviewed by Apple employees/contractors. Otherwise, they'd just keep doing it on the material that's actually uploaded.
- mannerheim 5y ago
- floatingatoll 5y agoIt’s incredibly stupid because your Apple ID will get terminated for abusing Apple services.
- falcolas 5y agoThere 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.
- floatingatoll 5y agoYou’re right that it’s a valid attack upon the people Apple pays to review matched images before invoking law enforcement, but no harm comes to the recipient in that model, unless they receive real legitimate CSAM and don’t report it to the authorities themselves. Attempted entrapment and abuse of computing systems, which is an uncomfortable way to phrase the WhatsApp scenario, would be quite sufficient cause for a discovery warrant to have WhatsApp reveal the sender’s identity to Apple. Doesn’t mean they’d be found guilty, but WhatsApp will fold a lot sooner than Apple, especially if the warrant is sealed by the court to prevent the sender from deleting any CSAM in their possession. A hacker would say that’s all contrived nonsense and anyways it’s just SWATting, that’s no big deal. A judge would say that’s a reasonable balance of protecting the sender from being dragged through the mud in the press before being indicted and permitting the abused party (Apple) to pursue a conviction and damages. I am not your lawyer, this is not legal advice, etc.