Hey.
I need a wireless connection to use it, right?
And I can’t use a selfhosted hotspot, right? It must be a second device, like an external hotspot or a modem.
And I authorize that device to adb level, right?
So if my modem is untrustworthy, it could install malware on my phone?
Thank you for clarification.
Ah, sorry, seems like I was wrong on the whole “no network connection needed”, but the reason is the explanation for your question!
The only way for your phone to recognize/authenticate the source of an incoming ADB connection is the MAC address. Basically every device that sends/receives ethernet packets has to have a unique “fingerprint”, so everyone knows it’s still the same device if it disconnects & reconnects etc. Everything else (IP address etc.) can change at any time, so the MAC address is the only fingerprint available.
But devices can spoof (change) their MAC address. That’s a really useful feature in many cases, e.g. phones these days use a random MAC for every new network, so a network provider can’t track you moving through multiple different networks. Also there’s no way to prevent it with our current network design. But this means that a malicious actor could wait for your trusted device to disconnect, then change their MAC to the one from your trusted device, and thus send malicious ADB commands.
Androids solution is to make you trust both the network and the device. So as long as you don’t have malicious actors in your trusted network, you’re safe - even if you connect to a different network with malicious actors, they can’t send ADB commands.
I see, makes sense. Thanks.
Hm, so, even if it is true that Shizuku-pairing directly privileges only the phone itself – that the adb commands never leave the phone – it follows that a malicious wifi modem, knowing all devices’ mac addresses, could, perhaps, feign being the phone, mac-wise. And issue its own commands, which the phone wouldn’t tell aren’t its own.
Unless adb privileges are also identified by the ip address of origin. Unless, the modem could also feign those and multicast them, or something. Could it?
Oh well. This is straying quite far from Android. Thank you regardless.
In any case, I just wish Android provided networkless self-debugging. On one hand, I oughtn’t complain, for I deliberately didn’t root my phone; but on another, I’d like to have a secure “halfroot” of adb at hand.
(Maybe root operations / grantings should have a pending time of 24 hours. Just to make sure the user / I have thought them through. And yes, I know root shall be able to erase that mechanism. The weakest part of all my setups is myself.)
I just tested some scenarios:
So you’re safe as long as you don’t start Shizuku & trust the network while connected to a potentially malicious network.
I agree 100%! It’s definitely possible to add a better API that would allow Android users to trust specific apps with ADB debugging connections. Unfortunately Google is hell-bent on restricting the platform instead of opening it up :(
That is a lovely analysis for this lowly thread of mine. Thanks again.
Thing is, I don’t trust my modem. Just on principle. It’s nonlibre software.
I’ll reread your posts in a while.
Right. The very thing I want adb for is, among other things, to install apps which Google arbitrarily declared obsolete (the api version declaration, I believe it is). I believe many good apps on F-Droid are uninstallable because of that. “This app is incompatible with your device” – no, you declared that it is.
And sadly – though that doesn’t seem to be Google’s fault – it still doesn’t seem possible to compile Android apps on Android, so I can’t just get sources, change the manifest, and recompile them and install them myself, to escape that.
But that’s for another thread.