Pass the Passkey: A Novel Attack Surface in Passwordless Authentication

(unit42.paloaltonetworks.com)

23 points | by jchanimal 1 hour ago

5 comments

  • MBCook 16 minutes ago
    Boy I’m so tired of people trying to make clever attack names. They don’t help remember things, there are too many.

    So all 3 “pass-ta-key” attacks are not attacks on passkeys, they’re attacks on the Google vault.

    And if you get access to the vault, then you get everything. OK. And if you get access to a synced traditional password vault, then you get everything.

    So… meh. These are bugs, they will be fixed. Good on them for disclosing them. But this does not prove that passkeys are terrible. This does not make them less secure than random passwords.

    If it wasn’t for the fact that they just happen to be getting passkeys, seems like this wouldn’t be worth a headline or discussing at all. And if they have this level of access, then they also get all the standard password credentials in the vault too, right?

    • nixpulvis 12 minutes ago
      Have we standardized a way to backup and export passkeys yet? Do websites commonly allow multiple passkeys to be registered?
  • tptacek 9 minutes ago
    These are endpoint malware attacks, not attacks on Passkeys per se. This is already a game-over position for an attacker to be in.
  • colemannugent 33 minutes ago
    >4. Using the hash of that handshake, the attacker interacts with the victim’s TPM and uses the extracted identity key to sign the handshake hash together with the assertion request

    Huh? If you have this level of local privileges you can just read session cookies from the browsers store? I guess stealing all the keys is notable, but you can manipulate any password manager with this level of access right?

    What's the threat model here, that synced passkeys should be secure in even in situations involving compromised clients? How?

    • ted_dunning 27 minutes ago
      It's not that simple. The stolen file has no clear text passwords and ideally, these passwords can only be decrypted on the right hardware with user confirmation. Of course, eternal and repeated confirmation requests are an anti pattern all their own, but the cloud attestation service not verifying the hardware sounds like a really glaring omission.
      • colemannugent 14 minutes ago
        It kinda is. If they use Chrome and it's cloud backed password manager, odds are they use GMail. That plus full access to a trusted device (which you have in this scenario) allows you to change their Google account password. Boom, full persistence.

        I can think of at least a dozen easier ways to do nefarious things with this level of access that are at least that simple. As an example, faking user attribution would be trivial.

        How could Google patch this? If the client is compromised and the attacker can manipulate the local TPM or it's equivalent there's no defense.

    • vel0city 25 minutes ago
      At least for accounts you want to keep very secure, session cookies are probably very time-limited. Stealing a passkey ensures persistent access in the future.

      But I largely agree, if they're able to do this on your system you're already hacked and they can do a ton of very bad things.

  • ted_dunning 46 minutes ago
    It is hard to find the content for all of the glitzy ads on this site.
    • ikidd 42 minutes ago
      There's ads?
    • ted_dunning 29 minutes ago
      But when you do, there are glaring holes these people uncovered.
  • Groxx 41 minutes ago
    "You must enable DRM to play some audio or video on this page" pops up in the strangest places...