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I would consider that as a bug, not as a feature. If the login panel behaves differently on a correct password than on a wrong password, that's an information l
by Rygian 4y ago
I would consider that as a bug, not as a feature. If the login panel behaves differently on a correct password than on a wrong password, that's an information leak that must be fixed.
Authentication must be evaluated and rejected only when all factors are already provided, and the rejection error should not disclose which of the factors failed.
So, with a proper login panel, my 2FA being asked does not mean that someone has my password.
Edit: this is, for example, the recommendation from PCI to separate "Multi-Step Authentication" from true "Multi-Factor Authentication": https://www.pcisecuritystandards.org/pdfs/Multi-Factor-Authentication-Guidance-v1.pdf https://www.pcisecuritystandards.org/pdfs/Multi-Factor-Authe...
- Semaphor 4y agoYou make a good point, but does anyone do that? I’ve been using a PW manager so long, I don’t really enter incorrect passwords.
- DangitBobby 4y agoI don't know of anyone who does 2FA this way.
- rexfuzzle 4y agoThis was posted above: https://www.isnic.is/en/site/login https://www.isnic.is/en/site/login First time I've seen it too
- Rygian 4y agoMy employer does it for products requiring PCI certification. Our PCI auditor recommends it even though it's not a formal requirement of PCI v3.
- darkarmani 4y agoThat sounds like a terrible trade-off that makes people more likely to write down passwords on post-it notes or in a clear-text file to cut-n-paste. Especially if you lock accounts after a 10 tries or so (or PCI's ridiculous low number of tries).
- anamexis 4y agoI think the majority of places I use 2FA, the 2FA prompt is on a screen after the password login. This is because the use of 2FA is an account option, so not all accounts will have it active.
- xwx 4y agoIf I've understood the linked post, the login panel doesn't have to behave or look different if someone gets the username and password right. You could still show everyone the 2FA input. It's suggesting that if the username and password are right but 2FA isn't the system should let the account owner know.
- runlevel1 4y agoCorrect. The blog suggests letting them know out-of-band, like via email, not in the login flow.
- Rygian 4y agoI have read the linked post too quickly before sending my initial comment. Indeed, a back-channel notification to the legitimate account owner is probably a good idea. On the other hand, disclosing to the attacker that they got the password right is not acceptable.
- jstanley 4y agoUnless you're an especially high-value target, I'd rather you gave quicker feedback about whether or not I have remembered my password correctly than you make it impossible to determine whether or not a password is correct without also having to input the 2FA token.
- medevacs 4y agoI'm under the impression you misread the original blog post, which by the way does not really do a very good job in terms of explaining how this should be implemented. IMHO, the idea is not to display the info about wrong 2FA code on the login page but to use a separate channel to inform the account owner about this recent, failed login attempt. So, no info on the login page of the website (adversary would still not know that they have a good password but wrong 2FA) but e.g. an email, a text message, a push notification, etc. with this info. I would certainly like to know that someone, somewhere is trying to login to my account and that this adversary is in possession of my actual password.