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But password managers typically don't send keyboard commands to fill in a password, so a physical device would be useless. > There are plenty of scenarios wher

But password managers typically don't send keyboard commands to fill in a password, so a physical device would be useless. > There are plenty of scenarios where MFA is more secure than just a strong password. And how realistic are they? Or are they just highly specific scenarios where all the stars must align, and are almost never going to happen?

mr_mitm 2y ago
I don't think phishing is such an obscure scenario. The point is also that you as an individual can make choices and assess risk. As a large service provider, you will always have people who reuse passwords, store them unencrypted, fall for phishing, etc. There is a percentage of users that will get their account compromised because of bad password handling which will cost you, and by enforcing MFA you can decrease that percentage, and if you mandate yubikeys or something similar the percentage will go to zero.
- RaisingSpear 2y ago
  > I don't think phishing is such an obscure scenario. For a typical person, maybe, but for a tech-minded individual who understands security, data entropy and what /dev/random is? And I don't see how MFA stops phishing - it can get you to enter a token like it can get you to enter a password. I'm also looking at this from the perspective of an individual, not a service provider, so the activities of the greater percentage of users is of little interest to me.
  - mr_mitm 2y ago
    > And I don't see how MFA stops phishing - it can get you to enter a token like it can get you to enter a password. That's why I qualified it with "certificate-based". The private key never leaves the device, ideally a yubikey-type device.
    - RaisingSpear 2y ago
      > That's why I qualified it with "certificate-based". The private key never leaves the device Except that phishing doesn't require the private key - it just needs to echo back the generated token. And even if that isn't possible, what stops it obtaining the session token that's sent back?
      - mr_mitm 2y ago
        The phisher will not receive a valid token, though, because you sign something that contains the domain you are authenticating to.
        deleted 2y ago
        [deleted]
        RaisingSpear 2y ago
        The phisher can just pass on whatever you sign, and capture the token the server sends back. Sure, you can probably come up with some non-HTTPS scheme that can address this, but I don't see any site actually doing this, so you're back to the unrealistic scenario.
        mr_mitm 2y ago
        No, because the phisher will get a token that is designated for, say, mircos0ft.com which microsoft.com will not accept. It is signed with the user's private key and the attacker cannot forge a signature without it.
        RaisingSpear 2y ago
        I think we're talking past each other a bit here. If I were trying to phish someone, I wouldn't attack the public key crypto part, so how domains come into play during authentication doesn't matter. I'd just grab the "unencrypted" session token at the end of the exchange. Even if you somehow protected the session token (sounds dubious), there's still plenty a phisher could do, since it has full MITM capability.

mr_mitm 2y ago

I don't think phishing is such an obscure scenario. The point is also that you as an individual can make choices and assess risk. As a large service provider, you will always have people who reuse passwords, store them unencrypted, fall for phishing, etc. There is a percentage of users that will get their account compromised because of bad password handling which will cost you, and by enforcing MFA you can decrease that percentage, and if you mandate yubikeys or something similar the percentage will go to zero.

RaisingSpear 2y ago
> I don't think phishing is such an obscure scenario. For a typical person, maybe, but for a tech-minded individual who understands security, data entropy and what /dev/random is? And I don't see how MFA stops phishing - it can get you to enter a token like it can get you to enter a password. I'm also looking at this from the perspective of an individual, not a service provider, so the activities of the greater percentage of users is of little interest to me.
- mr_mitm 2y ago
  > And I don't see how MFA stops phishing - it can get you to enter a token like it can get you to enter a password. That's why I qualified it with "certificate-based". The private key never leaves the device, ideally a yubikey-type device.
  - RaisingSpear 2y ago
    > That's why I qualified it with "certificate-based". The private key never leaves the device Except that phishing doesn't require the private key - it just needs to echo back the generated token. And even if that isn't possible, what stops it obtaining the session token that's sent back?
    - mr_mitm 2y ago
      The phisher will not receive a valid token, though, because you sign something that contains the domain you are authenticating to.
      - deleted 2y ago
        [deleted]
      - RaisingSpear 2y ago
        The phisher can just pass on whatever you sign, and capture the token the server sends back. Sure, you can probably come up with some non-HTTPS scheme that can address this, but I don't see any site actually doing this, so you're back to the unrealistic scenario.
        mr_mitm 2y ago
        No, because the phisher will get a token that is designated for, say, mircos0ft.com which microsoft.com will not accept. It is signed with the user's private key and the attacker cannot forge a signature without it.
        RaisingSpear 2y ago
        I think we're talking past each other a bit here. If I were trying to phish someone, I wouldn't attack the public key crypto part, so how domains come into play during authentication doesn't matter. I'd just grab the "unencrypted" session token at the end of the exchange. Even if you somehow protected the session token (sounds dubious), there's still plenty a phisher could do, since it has full MITM capability.