5 ms·

> I think you will have a hard time proving beyond speculation that Apple or Microsoft has backdoors to their OS. This statement is absurd -- they don't need t

by ohazi 5y ago

> I think you will have a hard time proving beyond speculation that Apple or Microsoft has backdoors to their OS. This statement is absurd -- they don't need to keep a backdoor around because they control the front door. You do realize that controlling how/whether/when core system software updates are pushed to a device is equivalent to having a backdoor, don't you? The operating system on my phone can be 100% backdoor-free today, but if Apple decides that their next update is going to include backdoor, then tomorrow my phone is going to have a backdoor. Basically all consumer phones (save for a few cobbled together exceptions) implicitly accept arbitrary software updates from their upstream vendor.

rsync 5y ago
"Basically all consumer phones (save for a few cobbled together exceptions) implicitly accept arbitrary software updates from their upstream vendor." Actually ... all phones of all kinds explicitly accept arbitrary updates from the carrier in the form of java code that they can upload, and run, on your SIM card. Your SIM card is a full fledged computer with CPU, RAM and storage and your carrier can upload and run arbitrary code on it.
- ohazi 5y ago
  Yes, this is absolutely also true. However, there are some phones (including several iPhone generations) where the entire baseband/sim subsystem is isolated from the primary application processor and operating system, and essentially appears as something like a dumb USB modem that the OS can control / use / ignore as it pleases. In theory, this would make it difficult for a carrier to issue a baseband update that (for example) hoovers up photos from internal storage. This is the same reason you should prefer a cable modem that's physically separate from your router/wifi/etc. Your cable modem gets firmware updates via DOCSIS from your ISP, and if you have one of those combo boxes, you're essentially letting your ISP onto your internal network.
  - Dah00n 5y ago
    >However, there are some phones (including several iPhone generations) where the entire baseband/sim subsystem is isolated from the primary application processor and operating system Yes, that's what the developer says. Totally unverifiable though unless it is both open source and you built and installed the firmware yourself.. and still there could be hidden firmware running. This is no different than Intel saying we can trust them with the Intel Management Engine.
    - ohazi 5y ago
      I agree with this perspective as well. Assume your carrier is capable of doing anything on your phone until a thorough hardware and software audit has been performed on the device in question (this kind of audit has been performed on several popular phones), but even then, continue to be careful/skeptical. It's also a good idea to at least consider the possibility that the baseband <-> application processor link may be software defined, and that an update from the vendor might theoretically be able to turn a dumb-USB-peripheral link into a has-access-to-kernel-memory PCIe link, thus enabling future control by the carrier.
      - rsync 5y ago
        All points well taken but I would suggest there is one way to have high assurance in this regard ... and that is to buy a non-phone device and add a cellular USB dongle to it, after the fact. Pretty unwieldy but given the economics of secretly throwing in a full-blown baseband processor with a SIM card that can function I think you can have high assurance that your carrier is fairly well segregated from your device ... In fact, there used to be a particular Samsung galaxy "pad" or something that was identical to a phones form factor ... but wifi only. EDIT: Samsung galaxy "player" IIRC ? As long as we're talking about it, I will mention one oft-overlooked downside to running a phone via external modem: in addition to cellular network functions your baseband processor is also responsible for a lot of real-time voice quality corrections and echo cancelling and related functions that are not handled by the application processor. You might, therefore, have voice quality issues with such a setup ...
        5y ago

by ohazi 5y ago

rsync 5y ago

"Basically all consumer phones (save for a few cobbled together exceptions) implicitly accept arbitrary software updates from their upstream vendor." Actually ... all phones of all kinds explicitly accept arbitrary updates from the carrier in the form of java code that they can upload, and run, on your SIM card. Your SIM card is a full fledged computer with CPU, RAM and storage and your carrier can upload and run arbitrary code on it.

ohazi 5y ago
Yes, this is absolutely also true. However, there are some phones (including several iPhone generations) where the entire baseband/sim subsystem is isolated from the primary application processor and operating system, and essentially appears as something like a dumb USB modem that the OS can control / use / ignore as it pleases. In theory, this would make it difficult for a carrier to issue a baseband update that (for example) hoovers up photos from internal storage. This is the same reason you should prefer a cable modem that's physically separate from your router/wifi/etc. Your cable modem gets firmware updates via DOCSIS from your ISP, and if you have one of those combo boxes, you're essentially letting your ISP onto your internal network.
- Dah00n 5y ago
  >However, there are some phones (including several iPhone generations) where the entire baseband/sim subsystem is isolated from the primary application processor and operating system Yes, that's what the developer says. Totally unverifiable though unless it is both open source and you built and installed the firmware yourself.. and still there could be hidden firmware running. This is no different than Intel saying we can trust them with the Intel Management Engine.
  - ohazi 5y ago
    I agree with this perspective as well. Assume your carrier is capable of doing anything on your phone until a thorough hardware and software audit has been performed on the device in question (this kind of audit has been performed on several popular phones), but even then, continue to be careful/skeptical. It's also a good idea to at least consider the possibility that the baseband <-> application processor link may be software defined, and that an update from the vendor might theoretically be able to turn a dumb-USB-peripheral link into a has-access-to-kernel-memory PCIe link, thus enabling future control by the carrier.
    - rsync 5y ago
      All points well taken but I would suggest there is one way to have high assurance in this regard ... and that is to buy a non-phone device and add a cellular USB dongle to it, after the fact. Pretty unwieldy but given the economics of secretly throwing in a full-blown baseband processor with a SIM card that can function I think you can have high assurance that your carrier is fairly well segregated from your device ... In fact, there used to be a particular Samsung galaxy "pad" or something that was identical to a phones form factor ... but wifi only. EDIT: Samsung galaxy "player" IIRC ? As long as we're talking about it, I will mention one oft-overlooked downside to running a phone via external modem: in addition to cellular network functions your baseband processor is also responsible for a lot of real-time voice quality corrections and echo cancelling and related functions that are not handled by the application processor. You might, therefore, have voice quality issues with such a setup ...
      - 5y ago