5 ms·

I don’t think banks are deliberately trying to avoid using TOTP, it’s just that they have to cater to the lowest common denominator, you know, the kind for whic

by xienze 1y ago

I don’t think banks are deliberately trying to avoid using TOTP, it’s just that they have to cater to the lowest common denominator, you know, the kind for which anything computer-related is basically black magic. SMS is an easy target because ~everyone has a cell phone and with things like Apple’s verification code auto-complete, the amount of friction is greatly reduced. With standard TOTP, now they have to worry about if the user correctly added the secret information to whatever authenticator app. And write corresponding documentation explaining how to do so, for every major authenticator app. There also has to be a backup flow for when the user loses their authenticator app which is probably just going to be SMS. So why not stick with just SMS in the first place? I hate using SMS for 2FA, but I understand the business decisions around it. I think as engineers we forget, to be frank, just how bad most people are with technology.

xp84 1y ago
This is no excuse for not offering it. And no, SMS must NOT be a backup that’s always available, as the article points out, its availability for use is a security hole. If you can’t access your actual 2FA there should be an option for the bank to have it call that registered number and ask you “Hey this is (Bank). Are you trying to log in right now from Moscow on a Windows 10 PC using Firefox? If so, please call the number on the back of your card, hit 9, put in your SSN, then we’ll turn off 2FA for one login and let you add a new one. Btw if it is not you, your password is definitely compromised.”
- xienze 1y ago
  > “Hey this is (Bank). Are you trying to log in right now from Moscow on a Windows 10 PC using Firefox? If so, please call the number on the back of your card, hit 9, put in your SSN, then we’ll turn off 2FA for one login and let you add a new one. Btw if it is not you, your password is definitely compromised.” Stop, do not pass Go, do not collect $200. Having someone call and ask for your SSN is a non-starter. And in what world is SMS not available but being able to call that same phone is?
  - jacobgkau 1y ago
    > Having someone call and ask for your SSN is a non-starter. That's not what he said. This hypothetical robocall would simply instruct you to call a different (known good, printed on your card) number to authenticate, at which point you know who's on the line. > And in what world is SMS not available but being able to call that same phone is? It's a good point about the robocall notification itself, but I imagine this kind of system wouldn't even need that to work in order to function. What actually unlocks your account is calling the bank's system and inputting your SSN; you could preemptively do it from another phone if you know you lost your 2FA codes and are trying to log in. This person's idea would replace your phone number being your authentication with your phone number simply being used for a notification, shifting the actual authentication to something the bank already knows but that someone who stole your credit card (and maybe your phone along with it) wouldn't inherently have. I got a bad whiff from it at first, but after thinking about it a little more, I think it's a good idea.
- error503 1y ago
  Recovery codes is an option, for one. Since we're talking about a legacy bank here, going to a branch and proving your identity is an option. Worst case, you could always call and speak to a human who will do whatever verification they do if you forgot your password, which is functionally equivalent.
  - aleks224 1y ago
    Do TOTP authentication apps typically provide recovery codes option? Can they squash all of the added TOTP codes you have in the app into one code?
Zak 1y ago
> With standard TOTP, now they have to worry about if the user correctly added the secret The standard flow I usually see for setting up TOTP ends with entering an authentication code. If it's not valid then the setup isn't finished.
- xienze 1y ago
  That's not what I'm talking about. I'm talking about the act of adding the secret to the authenticator app in the first place. There needs to be documentation to the effect of "open Google Authenticator, and if you don't have it, download it on the App Store or Google Play store. Open the app and choose 'new secret', ...". Probably also put in a QR code and link for good measure. Rinse and repeat for all the major authenticator apps. THEN you can have them verify. It adds up to a decent amount of supporting documentation that the bank is responsible for providing.
  - Zak 1y ago
    Outside of services like Github where the average user is expected to know what an RFC is, I usually just see Google Authenticator supported and no mention of the fact that alternatives exist. That seems like an adequate solution.

by xienze 1y ago

xp84 1y ago

This is no excuse for not offering it. And no, SMS must NOT be a backup that’s always available, as the article points out, its availability for use is a security hole. If you can’t access your actual 2FA there should be an option for the bank to have it call that registered number and ask you “Hey this is (Bank). Are you trying to log in right now from Moscow on a Windows 10 PC using Firefox? If so, please call the number on the back of your card, hit 9, put in your SSN, then we’ll turn off 2FA for one login and let you add a new one. Btw if it is not you, your password is definitely compromised.”

xienze 1y ago
> “Hey this is (Bank). Are you trying to log in right now from Moscow on a Windows 10 PC using Firefox? If so, please call the number on the back of your card, hit 9, put in your SSN, then we’ll turn off 2FA for one login and let you add a new one. Btw if it is not you, your password is definitely compromised.” Stop, do not pass Go, do not collect $200. Having someone call and ask for your SSN is a non-starter. And in what world is SMS not available but being able to call that same phone is?
- jacobgkau 1y ago
  > Having someone call and ask for your SSN is a non-starter. That's not what he said. This hypothetical robocall would simply instruct you to call a different (known good, printed on your card) number to authenticate, at which point you know who's on the line. > And in what world is SMS not available but being able to call that same phone is? It's a good point about the robocall notification itself, but I imagine this kind of system wouldn't even need that to work in order to function. What actually unlocks your account is calling the bank's system and inputting your SSN; you could preemptively do it from another phone if you know you lost your 2FA codes and are trying to log in. This person's idea would replace your phone number being your authentication with your phone number simply being used for a notification, shifting the actual authentication to something the bank already knows but that someone who stole your credit card (and maybe your phone along with it) wouldn't inherently have. I got a bad whiff from it at first, but after thinking about it a little more, I think it's a good idea.
error503 1y ago
Recovery codes is an option, for one. Since we're talking about a legacy bank here, going to a branch and proving your identity is an option. Worst case, you could always call and speak to a human who will do whatever verification they do if you forgot your password, which is functionally equivalent.
- aleks224 1y ago
  Do TOTP authentication apps typically provide recovery codes option? Can they squash all of the added TOTP codes you have in the app into one code?

Zak 1y ago

> With standard TOTP, now they have to worry about if the user correctly added the secret The standard flow I usually see for setting up TOTP ends with entering an authentication code. If it's not valid then the setup isn't finished.

xienze 1y ago
That's not what I'm talking about. I'm talking about the act of adding the secret to the authenticator app in the first place. There needs to be documentation to the effect of "open Google Authenticator, and if you don't have it, download it on the App Store or Google Play store. Open the app and choose 'new secret', ...". Probably also put in a QR code and link for good measure. Rinse and repeat for all the major authenticator apps. THEN you can have them verify. It adds up to a decent amount of supporting documentation that the bank is responsible for providing.
- Zak 1y ago
  Outside of services like Github where the average user is expected to know what an RFC is, I usually just see Google Authenticator supported and no mention of the fact that alternatives exist. That seems like an adequate solution.