4 ms·

Most people wouldn't realise they can't recover their TOTP codes. But the hacker would still need to know your password surely

• poincaredisk 2y ago
  ...so you agree that this is missing the '2' in 2FA?
  • buran77 2y ago
    For "something you have" to be true to its purpose it has to be something that has one and only one copy - so either only you have it, or you don't, but nothing in between. The second you have "cloud backup", or activate an additional device, or "transfer to a new device" then you turn the attack into "phishing with extra steps".
    • kibwen 2y ago
      You can support transferring to a new device without increasing the phishing risk, the transferral just needs to be done via a physical cable rather than via the cloud.
      • buran77 2y ago
        I'll grant you that it's a better option but by no means good if you want to stand on the 2FA hill and put security first (only?). That "just" does a lot of heavy lifting. The only time I'd consider transferring a secret like this is secure is within an HSM cluster. But these are exceptionally hardened devices, operating in very secure environments, managed by professionals. Your TOTP seed on the other hand is stored on any of the thousands of types of phones, most of which can be (and are) outdated and about as secure as a sieve. These devices also have no standard protocol to transfer. Allowing the extraction via cable is still allowing the extraction, the cable "helps" with the transfer. Once you have the option to extract, as I said, you add some extra steps to an attack. Many if not most attacks would maybe be thwarted but a motivated attacker (and a potential payoff in the millions is a hell of a motivator) will find ways to exfiltrate the copy of the keys from the device even without a cable. This is plain security vs. convenience. The backup to cloud exists because people lose/destroy the phones and with that their access to everything. The contactless transfer exists because there's no interoperability between phones, they used different connectors, etc. No access to the phone is a more pressing risk than phishing for most people, hence the convenience over security.
        • plagiarist 2y ago
          I don't understand the existence of an HSM cluster. I thought HSM was meant to be a very "chain-of-custody" object, enabling scenarios like: cryptographically guarantee one can only publish firmware updates via the company processes.
          • buran77 2y ago
            The HSM is more generic than that - a Hardware Security Module. It's just a hardware (usually, software... Hardware security modules exist...) device that securely stores your secret cryptographic material, like certificate private keys. The devices are exceptionally hardened both physically and the running software. In theory any attempts to attack them (physically open, or even turn them upside down to investigate them, or leave them unpowered for longer than some hours, attempt too many wrong passwords, etc.) results in the permanent deletion of all the cryptographic material inside. These can be server sized, or pocket sized, the concept is the same. Their point is to ensure the private keys cannot be extracted, not even by the owner. So when you need to sign that firmware update, or log into a system, or decrypt something, you don't use a certificate (private key) file lying around that someone can just copy, you have the HSM safely handling that for you without the key ever leaving the HSM. You can already guess the point of a cluster now. With only one HSM there's a real risk that a maintenance activity, malfunction, accident, or malicious act will lead to temporary unavailability or permanently losing all the keys. So you have many more HSMs duplicating the functionality and keys. So by design there must be a way to extract a copy and sync it to the other HSMs in the cluster. But again, these are exceptionally hardened HW and SW so this in incomparably more secure than any other transfer mechanism you'd run into day to day.
            • plagiarist 2y ago
              Ah, got it. So in the event someone managed to get access, they are limited to signing things in that moment on that infrastructure. I can see how that would reduce the blast radius of a hack.
        • crote 2y ago
      • crote 2y ago
        Ideally this would destroy the initial copy too - but forcing physical access would indeed be a great start.
        • buran77 2y ago
          Even so, if you have a copy even for a fraction of a second then you can have two copies, or skip the deletion, or keep the temporary copy that was used during the transfer. Even the transfer process could fail and leave a temporary file behind with your secrets.
    • radicality 2y ago
      I quite like Apple’s Advanced Data Protection, I set it up with two physical yubikeys recently. To login to iCloud/Apple on a new device that’s not part of your trusted devices, you must use the hardware token.
  • mavhc 2y ago
    They'd have to know your password, and get you to click your 2FA accept button, that's 2 factors still