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Comment on Does Shuzku / wireless debugging demand a trusted wifi device?

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.

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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.

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- FooBarrington@lemmy.world ⁨3⁩ ⁨days⁩ ago
  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.
  
  I just tested some scenarios:
  
  I start Shizuku in one wifi network (prompt to trust the network, then I had to enter the pairing code since I hadn’t used it before)
  
  Then switch wifi networks
  
  Shizuku was immediately disconnected
  
  When I press “Start” again in Shizuku, I get prompted to trust the network
  
  Then I switch back
  
  Shizuku stays running
  
  Then I disabled Wifi
  
  Shizuku stays running
  
  Then I disabled mobile data
  
  Shizuku stays running
  
  Then I stop Shizuku & press “Start” again
  
  It asks me to enable wireless debugging, and that enables wifi
  
  So you’re safe as long as you don’t start Shizuku & trust the network while connected to a potentially malicious network.
  
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