5 ms·

> he new YubiKeys support an on-device PIN that isn't shared with the server Doesn't this PIN become a master password for all the websites at that point?

• not_that_noob 8y ago
  That’s really the flaw of single sign-on and Webauthn - that one key now unlocks the kingdom.
  • zaarn 8y ago
    I don't see that as a flaw really. It's not different to having a password manager, with proper WebAuthn atleast. What you do is you take this key that unlocks the kingdom. And then you keep it safe. Unlike before there isn't 20 keys that unlock parts of the kingdom that might lead to unlocking other kingdoms via roundabout ways. Your attention for security can be focused on a single key. The average users will be much safer if we force them to only have to remember one single password that can be securely used for everything without the usual drawbacks (that's why security people recommend password managers)
    • not_that_noob 8y ago
      The flaw stems from the fact that an attacker can thru social engineeung acquire that root crendential (password or biometric or token). Once they have it, they can clean out all your banking, stock and home equity line accounts in one sweep. You as a user may not know that credential is compromised - maybe it was a key logger, maybe it was social engineering the cell phone provider to port your number and then qualify their phone with an sms token. You don’t know when that happened - you just see empty accounts. With personal password managers, no third party is issuing tokens for access - just you. So it’s unlikley to be chosen for an attack - because it’s too hard for the attacker to acquire the credentials for access without detection.
      • Freak_NL 8y ago
        Whether you use a hardware key, or a password manager, in both cases the attacker needs both authentication factors: your password, and the hardware key or password manager. With a hardware key you gain the advantage of the attackers having to physically gain access to that key.
        • not_that_noob 8y ago
          This is the misunderstanding attackers can exploit. Credentials need to be reissued because people lose them ocassionally. So that process now becomes a pathway for exploits.
          • emlun 8y ago
            No - that process _remains_ a pathway for exploits against the particular website being targeted. The process does not open new pathways for transferring exploits from one site to another - on the contrary, such exploits are made more difficult by the separation of credentials.
            • not_that_noob 8y ago
              See my reply to your other comment and review CTAP in the spec.
      • zaarn 8y ago
        Social Engineering is difficult problem with a solution quite simple; make the hardware resistant to replay attacks and don't give the user anything they can leak. Password managers don't protect against this. People have given attackers their entire password vault, all you need is a convincing story about some security audit and you needing to review all their passwords. Users believe this. The solution there is to take away the things a user can leak (passwords) and replace them with things that can only be stolen (tokens). We can train users to never give away their yubikey. Of course some will still fall for social engineering but for a yubikey/equivalent it's fully acceptable to say "never ever never give to anyone, no matter what they say".
  • StavrosK 8y ago
    It's not, you're misunderstanding and spreading misinformation. The "key to the kingdom" is a random asymmetric keypair. The PIN is only there as a second factor to this key to prevent physically stolen keys being used to authenticate. If you enter the PIN wrong five times, the device can just lock itself. There might be a way to steal the PIN if the user enters it on a compromised machine, but you can't do anything with the PIN. You need the physical device as well.
    • not_that_noob 8y ago
      I think you misunderstand how the CTAP portion of Webauthn works - once the root credential authenticates the user, they no longer have to use passwords for the user’s various accounts. The simple point is that if this credential became compromised for whatever reason, then all associated accounts are by definition compromised.
      • StavrosK 8y ago
        Yes, certainly. And in order to compromise that root credential, you'd have to physically steal the key, and either decap the chip and read the bits somehow, or find a vulnerability that allowed you to read the private keys through USB. Needless to say, this is much, much harder than stealing someone's password.
        • not_that_noob 8y ago
          Credential reissue (lost token) would be a much easier path for an attacker. The weakest point is always the point of compromise. For the smart attacker therefore, they have been handed the whole set of accounts. So yes the original point stands - attackers will find it more lucrative to do account compromise in the Webauthn world.
          • StavrosK 8y ago
            How would an attack without having the hardware key work?
  • emlun 8y ago
    To be more precise, the PIN is the key that unlocks the keyring (the hardware token) that contains the keys (asymmetic keypairs) to the various kingdoms (websites). WebAuthn is not a single sign-on framework, and there's no "root credential" that's used everywhere.
• emlun 8y ago
  In a sense, yes, but the keyword is "on-device". It's not shared with the server, so it can't be remotely intercepted - but it _can_ be changed in a single place (the YubiKey) should it ever be compromised.
  • emlun 8y ago
    Oh, maybe I didn't get the entire question. There's no global identity or "root credential" used for all websites. A separate keypair is created for each website, and a keypair for site A is not usable on site B even if site B somehow has the public key.