[RaisingSpear]

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]

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]

> 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]

> 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]

> 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?

[smw]

Doesn't work for FIDO-based tokens, they auth the site as well, so won't send anything to phishing site.

[RaisingSpear]

From my understanding, FIDO isn't MFA though (the authenticator may present its own local challenge, but I don't think the remote party can mandate it).

There's also the issue of how many sites actually use it, as well as how it handles the loss of or inability to access private keys etc. I generally see stuff like 'recovery keys' being a solution, but now you're just back to a password, just with extra steps.

[mr_mitm]

The phisher will not receive a valid token, though, because you sign something that contains the domain you are authenticating to.

[RaisingSpear]

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.