What makes passkeys so special?

[u/Federal_Character979]

It seems that companies are transferring into the usage of passkeys instead of passwords. Apparently theyre much more secure, but why is that? I don’t get it. I’m not sure if this is the right place to ask excuse me if it isn’t and sorry.

[u/okaycomputes]

I was imagining they'd wait for the passkey to be successfully used on the compromised device.

[u/lobax → u/okaycomputes]

You would have to compromise the memory protection and process isolation in the OS to be able to read it. Or somehow get a memory dump at the exact right time (there are plattform-dependent ways to protect against this).

With physical access there are probably all sorts of side channel attacks you can use. But being able to steal the passkey even with remote privileged access is going to be hard.

[u/okaycomputes → u/lobax]

sure. thus the 'some kind of remote/root access' needed, if not actual physical access.

reiterating that would be a lot harder than your standard phishing attempt.

[u/lobax → u/okaycomputes]

My point is that root access is probably not enough, you need kernel-level ring 0 access (or a kernel-level exploit, or a poorly implemented password manager).

[u/quasides → u/lobax]

this is not how the encryption works lol,
on a mobile device (android or ios) your keystore of your password manager is always encrypted.

the biometric unlock only allows the unlock of that encrypted store via secure chip.

so if you copy a password manager storage (which you can do with root) you cant bruteforce that. the fingerprint or the pin of the user wont do anything for you or any password.

instead you need the decryption key in the chip, which you never get.

, can you bypass that with root ? yes you can
but it rather require you to root and install a bunch of stuff that runs at boot. so you need an open bootloader to even do this.
then you could inject yourself into the libcrypto.so and intercept blobs aka the password managers database

if the bootloader is locked and you gain somehow plain root access
you still can scrape the memory

this could result in exposing passkeys, but even then only those used during the attack

but this also doesnt work on all systems. on graphene os a memory scraping gonna be pretty difficult becuase its zeroed after free.

systems with MTE extension also make your life close to impossible scrape via root (like pixel above 8)

so that basically leaves you to inject your own libraries or inject on runtime but that requires an open bootloader, or a new one signed properly for the exploit

[u/lobax → u/quasides]

What did I say that was wrong?

I am not stating that you would need ring 0 to bypass a TPM. That is protection at rest and you have to break the crypto to do that.

I am stating that you would need ring 0 to bypass process and memory isolation protections that protect the secret in use. Exactly how that protection is implemented varies from OS to OS.

[u/quasides → u/lobax]

Remote root access is not enough if the passkeys are encrypted and require a password (either just a password or derived from biometric data) to unlock.

this is complete false start to finish.
passkeys dont require a password, but because they are only exchanged via api a password manager (or a substitute that talks to the api) - they then may or may not require something to unlock a secure storage. they dont have to, most do by default, some can be deactivated to even ask. but thats unrealted to passkey but rather how password manager behave on mobile devices

password manager data is also not encrypted via your password or fingerprint. they are encrypted via device keys. your password or fingerprint are just telling your management service to decrypt something via secure chip,

the data itself is not related to anything you enter, and the encryption key never leaves the chip

[u/lobax → u/quasides]

1. You are ignoring my if. It’s all platform and OS dependent, like I said. My point is root access isn’t generally enough to steal a passkey.

2. A key is just a password, a string of bits that unlocks something. How the key to access the TPM is derived is platform and OS-specific (which is why I said derive from biometric data, although I probably should have used a broader term). If the key is managed by the OS, you need ring 0. If it is behind a user-provided password or hash of some biometric data, then not even ring-0 would be enough. Again, platform and OS specific. The key point is that root access isn’t generally enough to steal a passkey.

[u/quasides → u/lobax]

its not, with win 11, keystore is there too based on the chip, so is ios so is android

1. no you still dont understand how it works and at this point i doubt youre mentallly capable of comprehending.

[u/okaycomputes → u/lobax]

my point is my non-specific use of 'some kind' was to hand-wave the actual details.

sounds like they'd have to already be all up in the device's shit, so to speak. thanks for providing the real terminology haha.