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Comment by jpxw | Hacker News Reader

I’ve heard some people taking about using a raspberry pi zero or some other microcomputer to apply the exploit on boot, which sounds quite interesting.

As someone who used to jailbreak back in the day, this news was really exciting. However looking at it in a mature way than I did back then, it’s also slightly worrying that a whole class of iOS devices have a severe and unpatchable security flaw.

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> it’s also slightly worrying that a whole class of iOS devices have a severe and unpatchable security flaw.

"Severe" is a bit over-dramatic. To be accurate, from the article:

Checkm8 requires physical access to the phone. It can't be remotely executed, even if combined with other exploits

The exploit allows only tethered jailbreaks, meaning it lacks persistence. The exploit must be run each time an iDevice boots.

Checkm8 doesn't bypass the protections offered by the Secure Enclave and Touch ID.

> "Severe" is a bit over-dramatic. To be accurate, from the article:

Agreed. The hyperbole yesterday was millions of iPhones now have no security which does not seem to be the case. For the average user nothing has changed. For the paranoid, reboot the phone if it ever leaves your sight.

It's not easy to pull battery out, so we are left with a force-reboot button chord. That feature is probably meant to protect from normal, non-malicious bugs. How sure can the hypothetical paranoid be that the phone has indeed rebooted and not faked it?

The hypothetical user can be certain if they simply do a force reboot by holding power and volume, instead of shutting down using the power button long press and touch screen swipe.

Why? Is there any way to be certain these are done in hardware and can’t be caught in a low level system once the device is rooted? It’s a black box, so no way to know until somebody manages to pull it off.

Yes

Yup - this combination works even if the device is hung.

> Is there any way to be certain these are done in hardware and can’t be caught in a low level system once the device is rooted?

If you suspect your device has been tampered with and need a guaranteed reboot, just let the battery run down and don't use it until it has.

> If you suspect your device has been tampered with and need a guaranteed reboot, just let the battery run down and don't use it until it has.

Just a (overly paranoid) thought: a sophisticated attacker could simulate a drained battery and subsequent reboot, no?

No sophisticated attacker can make a phone run for five days without recharging. Just leave it on for five days and you should be fine.

I can implant a tiny microchip into your phone that will intercept every disc read/write and transmit it. Is that something it makes sense to check for, though?

These days, it's easier to thwart the Evil Maid attack, as it's known, by replacing the device, and some recommend doing that when entering/exiting China, attending DefCon, and a few other scenarios where it's credible under a given threat model. Most of us aren't Edward Snowden, but are still cases where thats not so ludicrous. The FBI has installed keyloggers into laptops supposedly fresh from the factory that have been discovered before. It's not just specific person devices, either. Aspersions were cast on Supermicro motherboards installed into Cloud provider data centers, even if nothing was ever found/proven.

I believe the force-reset button combination is a firmware (read-only) routine for that reason.

See: https://support.apple.com/guide/iphone/force-restart-iphone-...

Firmware updates are a thing for other devices. Sure, the force-restart logic should be stored on some separate device that isn't touched by any part of OS other than the firmware updater — but are you sure if it really is or should be read-only?

Nope I am not sure.

Not going to lie: I do place a significant level of trust in Apple's statements regarding their security architecture / model.

I'm inclined to place some trust in Apple too. Is there any statement that force-reboot is a security feature?

It might be patchable, even though it's in ROM. The ARM chip I've been working on has a mechanism to change a few words in ROM by blowing fuses... basically, between the ROM and the CPU sits a device that compares addresses and if matches what's found in the fuses, will replace the data being read. Since it doesn't have to be fast (since ROM code is only used at boot and there isn't a lot of it), they can slow down memory access to get more security.

Apple would've very likely patched it a long time ago if it was patchable, since the newest devices' ROMs don't have the bugs anymore.

Having a completely 100% untouchable ROM is very valuable. Yes, this kind of exploit being permanent is the downside, but then they don't have to worry about the modification fuses being misused in any way ever.

Why is that? I've long been against Apple's stance of not allowing me access to the hardware I own, and this exploit seems the best of both worlds: If you want to make sure you're secure, just reboot the phone.

If you can access using this so can others when you cross borders, are stopped by police, have spying spouse, etc. Those are real and sometimes fatal threat models.

If law enforcement did take your device, it would be useless if you have a passcode. Your data will still be encrypted.

depends on whether exploiting the bootrom allows you bypass the anti-hammering mechanism, or the "wipe data after 10 failed attempts" mechanism. A 6 digit passcode by itself is very easy to crack.

It doesn't. Just reboot the phone and it's secure.

I think you misunderstood the threat model. The concern is that they seized your phone, used the exploit to bypass the "normal" passcode protections, allowing them to bruteforce your 6 digit passcode in hours/days rather than years/decades/never (if you had the wipe after 10 failed attempts enabled).

That is not possible, the key is inside a hardware chip which enforces the number of tries for the PIN.

Now they do. That wasn't always the case though, for those on older devices (Anything older than the 5s, I believe), or older iOS versions.

IIRC from the San Bernardino case, that was the case on the shooter's phone (a 5S I think), but since then it has been built in to the "Secure Enclave" chip which is not affected by the vulnerability. But you could flash a fake iOS that logged the user's code and/or directly exfiltrated the data--the user would have no idea that it was not the stock iOS they were giving their code to. It would leave them which a bricked device the next time they rebooted, which could raise suspicions.

It was a 5c; 5s and later had the SEP.

You don't 'flash' a fake ios; you can use the bootrom exploit to put your modified version of ios into memory, and once you reboot you would get back straight stock ios. They could even make it reboot as soon as the password was harvested, leaving behind no trace. This is scary stuff. You can keep yourself safe by rebooting as soon as you get your phone back from border patrol, but many people would not know to do that.

You can use a numeric sequence passphrase as your passcode; there is no 6 digit limitation; I have a > 6 numeric passcode/passphrase.

You can also use an alphanumeric sequence.

Don't use a 6-digit passcode.

My take is that you’re misinterpreting what you (theoretically) have purchased. You bought an iPhone, not a pile of hardware. Nowhere in the transaction did Apple misrepresent what they offered. Your wish for iPhone shaped hardware that is yours to do whatever you want with doesn’t change the fact that this isn’t what’s for sale.

How do you reconcile the fact that I've bought it with the fact that it's not "mine to do whatever I want with"?

Ownership is the state of exclusive rights and control over property, which I don't have when I buy an Apple device. Either they shouldn't say they're selling it (they can say they're leasing it to me) or they should give me all rights.

World isn’t so black and white. There are restrictions on many things you “own”. Land, certain chemicals, technologies, etc.

I like to think of “owning” in the developed world simply as a right to collect rent from someone else.

> There are restrictions on many things you “own”.

Are any of these restrictions there so a private third party can decide what you do with your property?

Yes, land rights for example. Someone else decides what you're allowed to build and/or dig.

Which private party decides that?

Home Owners Association, Neighborhood Association, Historical Society, etc

The municipal council approves all building plans. Just because you own the land doesn’t mean you have the right to build whatever you want on it without approval.

At least, that’s true in at least one state in the USA.

The neighbor or utility providers have a say if there's an easement, e.g. you can't build as to block their right-of-way access for maintenance purposes, despite your ownership over the land.

Also the developers and architectural controls can make decisions affecting what you build (down to the color you paint outside), before they turn things over to the city.

All subject to local laws of course, so may vary city to city.

Another example is the Visual Artists Rights Act. You may own the painting, sculpture, etc., but you are not allowed to modify or destroy it.

When you buy a car, you don’t get an airplane. Maybe you can figure out how to make it one but don’t cry when you can’t.

This analogy is apt, because I was clearly complaining that my phone wasn't a spaceship.

You knowingly bought one thing while wishing it was something else. Blame the company for that if you want but they didn’t have a gun to your head.

I'm not saying they misrepresented the transaction that occurred. I'm saying I don't own the phone I bought, Apple does. I'm just leasing it from them.

I guess I just don’t understand your definition of ownership or leasing. This just sounds to me like you’re complaining that you’re only leasing your fork because you bought a spoon.

I bought a computer that can't run whatever code I want. That's not ownership. That's buying a fork that hangs on a chain in the manufacturer's house. Yes, I "own" it, yes it's better than no fork, but if I can't eat whatever I want with it, it's not really mine.

I don't know what people aren't getting about this. You bought a computer that can only run code that Apple has explicitly approved. How is this ownership?

this is like saying you don't own a lock because it won't open if you've lost the key

No, it's like saying I don't own a lock because Apple keeps the key and I have to call them and ask them to unlock it for me every time.

If you lost your iPhone or it was stolen it was just a worthless brick for the finder/thief. Think about what a big peace of mind that is! This changed now for older hardware.

It didn't, because the encryption keys are in the secure coprocessor.

Your data is protected, but the iCloud activation lock can be bypassed. Hence it no longer being a brick.

What's the market value of a phone that has to be put into firmware upgrade mode every time it restarts?

TBD. Check out eBay in the coming months, I’m sure a value will be determined soon. It’s definitely higher than what it is now (sold as scrap for parts)

My suggestion is to build it into a battery case. Then you always have the device with you and it's always charged if your phone is, preventing catastrophic dead phone in the desert scenarios.

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