Comment on Does Shuzku / wireless debugging demand a trusted wifi device?
FooBarrington@lemmy.world 4 days ago
- You don’t need to be connected to a network to set Shizuku up. Even while you’re not connected to an external network (through Wifi or mobile data), your phone has a “loopback” network that allows applications on your phone to talk to other applications as if they were connected through an external network. So if you’re scared of giving access to the wrong thing, just turn off wifi & data.
- When Android asks you to approve an external debugging connection, it’s approved for the specific device that’s connecting. Other devices on the network are not allowed to connect. If I use my computer to connect wirelessly to ADB, only my computer can execute commands, not other devices on my network (they’d show another popup).
Hope this helps!
wyfpm@lemdro.id 4 days ago
Perhaps my question had semiconsciously stemmed from this:
Why would Android ask me to authorize a whole network for wireless debugging, if it then proceeds to demand device-permissions anyway?
I understand it is just a second layer of security, or, a relic of times when wifi connections were unencrypted. But if so, then wireless debugging should be just unenanable if elsewhere in Android settings, insecure wifi networks are enabled / if you presently are on one.
(Is adb encrypted anyway, as a protocol itself? If I authorized, say, my laptop, wirelessly, would the modem be able to read my comments? Those aren’t questions for you, btw, just musings. I should probably hit ai / Github for those.)
FooBarrington@lemmy.world 4 days ago
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.
wyfpm@lemdro.id 4 days ago
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.
FooBarrington@lemmy.world 3 days ago
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.