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Comment by mirimir | Hacker News Reader

Because phones are totally insecure.

The only secure option is using an external WiFi or cellular data router for Internet connectivity. The router can of course be geolocated. And adversaries may gain some access. But it should be possible to prevent access through it to the phone. That is, it's a firewall.

Then do end-to-end encrypted Internet stuff, messaging and VoIP. And by using some mix of VPNs and Tor, adversaries won't even see most metadata. Except for communication timing, of course.

See https://blog.torproject.org/mission-improbable-hardening-and...

Edit: But this still doesn't protect from some third party with root rights on the phone. For Android, the Copperhead OS might be enough. But I don't know enough to know. And for iOS, I suspect that you're stuck trusting Apple.

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Belated edit: I forgot to mention that you must also prevent cellular and WiFi connectivity on the phone itself. The Tor Project article recommends airplane mode on Android. But it mentions the option of wiping baseband firmware. Which apparently also takes out GPS. Probably risky, though.

iOS's only security issue is users not updating and being vulnerable to well known vulnerabilities. Neither iOS nor Android will survive a truly targeted nation state attack, but for most people 0-days aren't worth protecting against.

The only exception to this is the checkm8 vulnerability, which can be performed on an A11 and older chips (so iPhone XR/XS/XS+ and 11/11 pro/11 pro max aren't vulnerable) from DFU mode, which doesn't need the device passcode.

Right. I guess that phones can't update without direct cellular or WiFi connectivity. But I don't know.

Is that true?

Could one somehow enable updates through pure TCP/IP?

Carrier updates might have some power i'm not aware of on iOS (they pop up saying "do you want to update carrier settings" with simple yes/no options), but regular iOS software updates do require connection to Apple servers and the firmware itself also has to be signed by Apple.

The carrier setting thing hasn't ever been use for a jailbreak exploit AFAIK so chances are it's not a good attack vector.

From your other comment:

> But it mentions the option of wiping baseband firmware

iOS also has signature verification for its baseband, since trying to load an incompatible one during a downgrade[0] breaks Face ID / Touch ID.

But ya, this is all "trust apple to not do anything". They've made a good stance with refusing the FBI request[1], but the FBI got into the phone anyways[2].

0: https://github.com/tihmstar/futurerestore

1: https://news.ycombinator.com/item?id=11116274

2: https://venturebeat.com/2016/03/28/u-s-government-gains-acce...

I guess that a key question is whether one can trust iOS airplane mode to fully take the phone offline.

And under what circumstances does the phone leave airplane mode, and go back online.

But even if that were solid, you'd still be ~unable to install apps that Apple doesn't provide. Unless you play the developer game, and I gather that's limited in app number, and how long they'll stay functional.

> whether one can trust iOS airplane mode to fully take the phone offline.

I mean, if Apple says airplane mode turns off the cell radio, that’s a falsifiable claim, so you don’t have to take it entirely on faith. It might be possible to hide it in the UI, but you can’t hide a radio signal.

Right, but I was most curious about the persistence of the setting.

Say you set airplane mode. And then the phone sleeps. Will it still be in airplane mode after you wake it?

Or say you shut the phone off, and restart it. Is it still in airplane mode?

That's an issue because, as soon as it's not in airplane mode, it knows where it is.

And that reminds me, does airplane mode disable GPS? Because if it doesn't, it's more or less pointless, from a geolocation perspective.

>Say you set airplane mode. And then the phone sleeps. Will it still be in airplane mode after you wake it?

>Or say you shut the phone off, and restart it. Is it still in airplane mode?

Yes.

>And that reminds me, does airplane mode disable GPS? Because if it doesn't, it's more or less pointless, from a geolocation perspective.

Why does that matter? You can turn location services off. Moreover, GPS functions passively. Turning it on doesn't transmit your location to anyone.

OK, that's good about airplane mode.

> Why does that [GPS] matter?

GPS matters because it's important that the phone doesn't know where it is. I mean, if it doesn't know where it is, there's no need to worry that adversaries will access the information.

> You can turn location services off.

Off entirely? Even for the OS? Or for rogue apps?

> Turning it on doesn't transmit your location to anyone.

No, but it generates location information that could leak. And if the phone uses WiFi to supplement GPS, it necessarily communicates with some remote server.

>GPS matters because it's important that the phone doesn't know where it is. I mean, if it doesn't know where it is, there's no need to worry that adversaries will access the information.

So your threat model is that you can't trust the device itself? If that's your threat model, you'd probably need a phone with hardware kill switches. Also, if you can't trust the device itself, why would you be carrying the device around? What would you use it for?

>No, but it generates location information that could leak. And if the phone uses WiFi to supplement GPS, it necessarily communicates with some remote server.

On android you can explicitly disable that ("device only" in location settings). There's no such option on ios, although you could still disable wifi/bluetooth and still have working gps.

> So your threat model is that you can't trust the device itself?

Yes. I don't trust a phone OS where I lack root privileges. And I entirely don't trust the baseband.

> If that's your threat model, you'd probably need a phone with hardware kill switches.

Yes. Or with disabled GPS, baseband and WiFi. And with Internet connectivity via external WiFi router, or cellular modem/router.

> Also, if you can't trust the device itself, why would you be carrying the device around? What would you use it for?

I'd use it as a phone. Albeit just using VoIP.

And if I had all the iffy stuff in a separate device, connected via USB, I could trust the phone as much as I trust the host machine I'm using now.

I mean, I'm working in a Debian VM that hits the Internet through a nested VPN chain. And the Debian host has no access to GPS or WiFi. So I'd want to replicate that on a phone.

You can update iOS devices through iTunes via USB, or buy an ethernet adapter.

But your computer does need internet, see https://support.apple.com/en-us/HT201442

> If your computer can’t communicate with Apple's software update server, you might see one of these messages.

But at least I have more control over what my computer does when it connects to the internet than I do over what my phone does.

Cool. So you could take the phone/tablet totally offline, except for external router via USB.

Maybe same for Android?

Except that you'd arguably want to update it locally with the Copperhead OS.

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