[azinman2]

There’s a difference between logging into Google via 2FA and having subsequent interactions not require the 2nd factor, and turning off 2FA without a reconfirmation. You don’t want maximum usability in disabling your security mechanisms.

[UncleMeat]

What threat model concerns you here? Anybody who'd be able to disable 2FA already has access to my logged in Google session on a trusted device. The game is over.

[zaroth]

Right. Instead of debating the headline, this is the real question. The current behavior is that "someone on a 2FA authenticated session can disable 2FA". OK, so what?

Google is intentionally leaving this route open to lessen the impact of a lost authenticator. Probably this is a very significant cost savings for them -- although I don't know what their account recovery policy is for "lost" 2FA.

I'd say one risk factor here is that if someone is able to piggyback your session (e.g. CSRF) specifically into the 2FA Settings API, they may be able to get your 2FA disabled in a way that meaningfully exposes your account to a wider attack.

Another risk is similar to why you should require a password to be re-entered in order to change a password. The user is already in an authenticated session, and yet, it's still considered best practice to prompt for the existing password at the same time. This can't merely be as a second layer of CSRF protection, right? If your CSRF is broken, fix your CSRF.

I would assume the theory is to prevent an opportunist attacker with a small time window of access to your session (keyboard) from getting longer term access to your account.

Particularly for accounts that have long-lived sessions that don't have to use 2FA very often because of the cached session, you might not notice for quite some time that 2FA is no longer active.

As with most things in security, it's a double-edged sword.

[bluesign]

"Another risk is similar to why you should require a password to be re-entered in order to change a password."

you know that google asks your password when you want to change your password right?

[unloco]

and he is comparing the two. Why ask for password before changing a password? Why not ask for 2FA before changing your 2FA?

[bluesign]

to be honest I am on the side that thinks asking 2FA to disable 2FA is not necessary, now I read my comment again, it sounds like I was on other side.

on both cases, password change and 2FA disable, it is asking password (but not 2FA)

So I think when you are logged in it is 1st factor, 2nd one is password. No need for 3rd one.

[golem14]

Pragmatically, I believe the threat is that someone has managed to install some malware on your phone/computer/... you are 2FA logged in.

If so, then the bad guys can disable 2FA on your account without you having to prove the 2FA token. [Edit: but nowadays, at least you get emails and device notification that it has happened]

Traditionally, security teams have thrown up their hands and said - with malware installed, all bets are off.

I'm not sure I agree with that assessment these days, with state sponsored 0-days and trojans. I think that OPs sentiment is right, and Google and others should require 2FA reauthentication to remove 2FA, especially for their 'titanium' security tier.

BTW, it's interesting to ask what is the downside of requiring 2FA re-authentication: I believe the reason to not require 2FA is historical: When it was initially rolled out, a bunch of people tried out 2FA because it was the new coolness, got somehow lost and immediately wanted to disable it, but are not able to (lost token, have no idea what the heck they are doing etc) and get stuck. Since 2FA account recovery is very manual and expensive, Google probably doesn't want to take that hit.

[pdpi]

An attacker gaining access is one problem.

An attacker disabling and then promptly re-enabling 2FA (thus locking me out of my own account) is a different problem altogether.

[baby]

Debatable. If you lose your second device but still have access to a logged account you want to be able to disable 2FA.

[azinman2]

This defeats the point of 2FA if you can turn it off without that second factor. In your example, if you don't have that authenticated session then you're still screwed... so you must design for the worst case scenario. The risk of 2FA is losing a device, which is why a proper design has other safety backups, such as backup codes, or leveraging a combination of other accounts that can vouch for you and humans in the loop.

[baby]

> This defeats the point of 2FA

that's not true. You need to think of a threat model. 2FA still successfully prevents attackers that do not yet have a session to connect to your account.

So it is still a clear net benefit.

What it does not prevent, is attackers downgrading your account from a session that already exist. At this point it is easy to argue that if an attacker has this kind of access then the only thing you can do is add 2FA to all critical actions, not just removing 2FA (that would be the least of your issue), but every critical action you can do in the app.

For example if the app is a bank, and wants to protect against these kind of attacks, then they have to prompt 2FA every time you want to want to send money (at least).

[anon102010]

You already have authenticated your computer as the second factor. The article headline implies you can just use a password to remove 2FA. False.

You can use your password AND that authenticated and still valid session or device to do the reset.

Google gives you options with your free account.

1) No 2FA

2) 2FA with insecure methods

3) 2FA with security keys and authenticators.

4) Advanced Protection Program

5) Paid account options with additional options / controls.

[hombre_fatal]

Great counter-point, it's not as black and white as it seems.

Google's own 2FA app (Google Authenticator) doesn't even let you export your keys.

[graton]

Actually the newest version does allow export. For years it was true you couldn't export. But now they allow you to export. Thankfully.

Though I tend to use U2F. With Yubikeys and other U2F keys. I use my Yubikey to store a backup of the TOTP (Authenticator type) codes. I also set a password and touch required to generate the codes.

[mathisonturing]

If you're talking about importing/exporting your list of 2FA codes, I think they've added it

[fasterthanlime]

They have! But only via QR codes (multiple, if needed). It's clearly meant to help migrate your TOTP secrets to a new phone.

[duncanawoods]

Have they? I can't see it on their IOS App version 3.01. It's only had two updates in 4 years for cosmetic stuff.