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Would this mean that hypothetically, your SIM could send SMS messages even if your phone is in airplane mode?
by kevingadd 5y ago
Would this mean that hypothetically, your SIM could send SMS messages even if your phone is in airplane mode?
- dboreham 5y agoNo
- striking 5y agoIt doesn't have a radio, so no.
- catlikesshrimp 5y agoUnder normal conditions: no. But a hacked phone may fake going offline and still be connected. The only way to turn off a phone for sure is to remove the battery.
- raldi 5y agoI think that’s the lesson of this article — the SIM can instruct the phone’s radio to send and receive any sort of data (including SMS) without the rest of the phone ever knowing about it.
- judge2020 5y agoMy understanding is that airplane mode does disable the radio entirely - so the SMS card trying to send messages wouldn't work unless the baseband (which, on iOS, is signed by apple and likely not an unknown binary blob to them) turned the radio on, let it connect to the network, sent the message, then turned off the radio, all without informing the OS.
- kevin_thibedeau 5y agoYou're assuming Apple doesn't have a way to bypass airplane mode when they receive a warrant.
- Thorrez 5y agoApple heavily resisted building a backdoor that would only be installed on a phone the FBI already had in their possession. Why would they build a way to bypass airplane mode if they receive a warrant?
- judge2020 5y agoMore so, how would they tell a phone with radios disabled to turn on a radio, besides physical access?
- b112 5y agoBy telling the radio firmware to do so? edit: the sim can tell the radio to turn on, when it wants to send a message. It is a full blown computer, with direct access to the radio firmware, with no OS oversight. The radio firmware can be updated remotely, too, and the OS only knows the modem is on, because the firmware tells it so. The icon on your phone showing signal/on/off is displayed by the OS, after querying the firmware. The OS has no way to know if the radio is on or not.
- vermilingua 5y agoYes but from where is this command originating? Can't be remote because well... the radio is off.
- PeterisP 5y agoIt can be remote but shifted in time. E.g. send a remote command that essentially says "if in airplane mode, every 60 minutes turn radio on and check for new commands".
- lxgr 5y agoDepends a lot on how airplane mode is implemented on a given device, I'd say. To my knowledge, this is not specified by the relevant standards. One way would be to shut down the SIM as soon as it's activated, which would include proactive commands of any kind (like those the SIM uses to request sending an SMS from the phone/baseband). Another would be to keep the baseband and SIM active, but to still deactivate the radio – in this the SIM might still be able to issue proactive commands, but without any network attachment, they would just fail. Of course an implementation could also choose to briefly reattach to the network whenever it receives such a proactive command.