Adding a security key to Gmail
techsolidarity.org
techsolidarity.org
Google Authenticator stores the TOTP secret in plaintext on your device where the potential exists for it to be stolen. An adversary that exploits your phone can generate TOTP tokens as they like and ignore the fact you have a hardware token. If you are going to use Google Authenticator it is your weakest link and a security token buys you no added security, only ease of use.
The typical goal of a security token is to be able to assert: "No one can log into my account without this physical device or an offline backup token from my safe"
To acheive this consider a device with built-in TOTP support in addition to U2F. All current Yubikeys fit the bill here as as well as some Nitrokey models. Desktop or Android users can use the either USB or NFC devices but it is worth noting that iOS lacks support for either which means you would need a desktop or Android device to fetch TOTP tokens for an iPhone.
You can use the open source "Yubico Authenticator" apps to store your TOTP secrets in your key alongside your U2F secret. Now both methods use the same hardware and your phone/computer only get handed OTP codes from the key if present, but can't generate them itself.
Added bonus is now you can now use security token backed login even on the majority of sites/browsers today that lack U2F support.
Extra bonus is these keys can be used for ssh without any server changes. Security token all the things :)
Simple GPG setup: https://github.com/lrvick/security-token-docs/blob/master/Us...
Advanced GPG setup with backups: https://github.com/lrvick/security-token-docs/blob/master/Us...
SSH Setup: https://github.com/lrvick/security-token-docs/blob/master/Us...
I also will be adding an alternate "quick ssh setup" guide via PKCS#11 flows to just store an existing ssh private key. Still I think GPG is the way to go in general given all the other use cases it opens up.
Please file issues with anything you want to see! I have a lot of unpublished content I can get polished/up if people care.
Security tokens are a nice little bonus for security, and they're a major corrective for the kinds of real-world attacks that screw real people over, like phishing (and dumb passwords). But they're pretty marginal against the kinds of attackers who will target SSH keys. Don't get fetishistic about them; at bottom, for serious systems security, they're mostly cosmetic. It feels good to say that all your SSH keys are held in secure devices, but it doesn't mean much.
I can even do agent fowarding taboos and know an attacker can't go creating new connections on that agent without a physical action from me each and every time.
Compare this to how ssh keys are normally used. You use it once, type in a keyloggable passphrase, and the key is unpacked plaintext into system memory for, in most cases, the rest of the time the system is booted.
You could invalidate the passphrase after every connection but this puts an unreasonable amount of work on the developer.
Simply tapping once for each connection and having no way for an attacker to avoid that is a great middle ground, imo. Particularly for high level production keys.
I am arguing it is not all that marginal. If the only non 0-day way into production is via ssh to a bastion host with a touch-based hardware token then their lives are more than marginally harder than an on-disk key.
Both of course assume you have the secret key on a Yubikey, Nitrokey or similar.
Any app-only TOTP solution has to expose your private key somewhere by design and thus are best avoided in favor of hardware-backed solutions when possible.
We need all the help we can get on that until TOTP is finally phased out.
Security is hard enough when everything is open source. Closing foundational security tools so only a select few biased individuals can deem them secure on a deadline is never a good plan.
Even without root. Just run a backup and extract it from that. You can do it with just adb or helium.
--
I can't quickly find any examples online that don't specifically mention requiring rooting the phone. Just this anecdote: https://community.spiceworks.com/topic/465582-google-authent...
If you do a backup (even if not rooted you can use ADB to backup your apps and data,) then you can simply restore the app and data to your new phone and the codes for the device come with it.
This article appears to contain the most detailed instructions, stating that both Titanium backaup and manual extraction require root: https://www.howtogeek.com/130755/how-to-move-your-google-aut...
If your Android is rooted, you can use Titanium Backup, which we’ve written about before, to take a backup of your Google Authenticator app data. [...] If you have root access to your device, you can actually extract the credentials manually
It was at one point possible to extract from iPhone backups: https://dpron.com/recovering-google-authenticator-keys-from-...
Source: I've tried.
Depending on who you work for, someone might just burn a 0-day on you. It all depends on your threat profile.
Putting the secret in a hardware token gives you easy to reason about assurances a mobile phone OS vendor can't ever offer.
Also this means when you get a new phone, you just install app and tap key. No setup required.
Easier for you, and far more secure. Win/win.
When we work with lawyers, reporters, and NGOs, what we find are people with much more urgent security problems. They're one carefully worded email away from giving their entire email account away to a 25 year old in Estonia. They aren't worried that their phone is about to get owned up --- mostly because that isn't going to happen, but for other reasons too.
Real targets are going to be compromised for 3 reasons:
1. They're going to be phished out of losing their credentials.
2. They're going to share credentials between sites and lose them in a breach of one of those sites.
3. They're going to click on an attachment and lose their whole computer to an attacker.
The U2F/TOTP stack this post recommends nicely addresses (1) and (2), and nothing anyone on this thread is talking about addresses (3). I'm not sure why we're spending so much time considering (13).
That access can be lost because of an attack or by losing the keys. The former is actually much less likely than the latter so mitigating in favor of it instead doesn't make sense in this threat model.
There have been plenty of iOS exploits as well as Android and everything else. Phones have a lot of attack surface and are not a reasonable place to store 2FA of any kind, IMO.
The separate hardware TOTP device never exposes the private key to system memory or disk at all. Even if your phone was rooted by a remote attacker, they could not generate tokens.
Likewise even if someone physically stole your unlocked phone and your pin-protected key... you are still in pretty good shape.
With a hardware TOTP device is just a "viewer" for one code at a time, as generated by the token.
The threat modeling here just doesn't make sense.
You are coming at this from a threat profile of joe individual user. Okay, point taken.
I am talking about the perspective of trying to take every reasonable step to reamin secure while being targeted by skilled adversaries who have a lot to gain if they succeed. It is not that much extra work to reduce attack surface so much further than TOTP-generator-on-a-phone offers, so why not teach anyone best practices that will listen?
Say I have 30+ TOTP secrets in my mobile phone app, and also my password manager. Everyting from Gmail to my AWS root account.
If the TOTP secrets are on my phone and an attacker compromises my phone... they get -everything-. If I am using a hardware token for TOTP and I quickly expire the sessions of all really important things I don't log into often, like AWS... then an attacker only gets a slice of the farm instead of the whole thing.
What this buys is us is damage control and a much clearer picture of what an attacker could of accessed, and what they probably could not of because no cookies or secrets were available to memory or disk at that time. I can assert -maybe- this one token was phished, but that none of the others were at risk.
If the attacker is on a phone with Google Authenticator, they an just generate all the codes they want for every service. We lose the whole farm.
I promise you, my security requirements are as stringent as yours are. My 2FA stack is Hardware U2F, Software TOTP, and physically secured backup codes. That's what I recommend. You keep suggesting that this stack is inferior to yours, and I keep explaining why it isn't and why the threat model suggesting to you that it is is incoherent.
Say we each have TOTP for say 20 accounts and our password managers on our phones with the credentials for them as well. We are system administrators with access to piles of PII. Account password resets require 2FA so email alone is not enough to spider to other accounts.
Both our phones have been rooted and are accessible by a remote attacker because some "coworker" sent us a new beta app that was in fact malware.
In both cases the attacker has all our passwords to all apps via our password managers. That is lost.
We each are logged into 5 of these services and the attacker steals the cookies. Those are lost.
Now what about the remaining 15 services we are not logged into? Things we don't log into super often but some of which ar quite important like AWS root credentials.
In your case, the attacker goes and opens the Google Authenticator sqlite database and gets every TOTP secret you have in plain text. You just lost all 15 remaining accounts.
In my case those secrets exist on a hardware token and can't be accessed at all. If I catch my intruder at this point I can be reasonably sure those remaining accounts were not impacted.
Hopefully this clarifies the wider model I am working from.
This is reasonable when you consider that if your computer --- the least secure device you own --- is compromised, your attacker is virtually certain to get your email account with it, because you'll have (at some near point) a logged-in session.
Meanwhile: the #1 concern that laypeople have about security tokens is that they'll be locked out of their account when they lose the token. Authenticator (or Duo) is a perfectly sane answer to that concern.
Finally, it's worth adding that at least the last time I helped someone set this up, you can't remove your phone number as a factor from your Google account until you have TOTP set up. Your phone number is an extremely insecure login factor.
We use, and recommend, Google Authenticator as a backup login factor.
We do not recommend Yubikey 4 keys for normal users. Nerds on HN might get a kick out of them; I say, go ahead and enjoy yourself. We're trying to solve problems for people who aren't computer experts.
I have never had any problem helping someone that has used google authenticator set this up. Scan barcode and tap.
Also users have a much easier time when they get a new phone. Just tap to new phone and get codes. There is no data to transfer.
As for people getting locked out, that is what the printable backup codes are for, or a secondary key, depending on your threat profile.
In a corporate setting this is a non-issue as an admin can bail you out.
And all this for what real additional security?
If you want to nerd out and get your security key to do pet tricks like handling your TOTP secrets, I do not have a problem with that. But please don't tell ordinary users they're wrong when they don't do that.
The android app is a direct fork of google authenticator and has nearly identical UX.
I tap/plug my key to either of them to get a token.
If you want to make the argument TOTP via hardware token is overkill for most users, that is totally fair. On that note though, there is no point in having hardware token via U2F.
Security is ahout the weakest links. All I am saying is anyone going through the trouble to set up U2F as this guide suggests, might as well spend the extra 10 seconds to store their TOTP secret on the key as well, vs exposing it on the phone.
I assume someone that has a hardware token is getting it for a reason: To have assurances an attacker can't log in as them without that token.
It would not be much of a stretch to say that this U2F guide was written deliberately as a corrective to this mindset.
Your cost/benefit considerations prioritize relatively miniscule security improvements without considering usability costs or diminishing returns. While we're at it, why don't we just use one-time pads? After all, those are impervious to any form of cryptanalysis.
The risk profile for most users does not require a hardware-based auth factor if it results in real world usability sacrifices that end in either 1) accidental misuse or 2) gradual disuse.
You're optimizing for someone compromising the device, great. But the point is that if that risk if on the table, all of this work is essentially meaningless anyway.
I can't agree with this strongly enough. If someone's willing and able to hack your iPhone, then you need more help than a random art major writing a yubikey howto can give you.
I like knowing that if the phones and laptops of someone on my team were compromised, we have some damage control.
With the approach Yubico Authenticator takes an attacker with remote access to your Android Phone and a keylogger on your laptop still can't log in as you remotely.
Granted with more effort that combo can burn you in other ways, but TOTP on a hardware token still gives you some very real reduction in attack surface with no real added user burden. Why not?
This is not the thing to optimize for. Yes, optimize for ease of use, because take PGP as an example of great security vs horrid usability and look where that's got us. If you do the security improvement analysis from a cost/benefit perspective, you do not win by using a hardware key over regular 2fa apps. Users will shoot themselves in the foot, or simply not use it.
It does not store the secrets on the disk/memory of the phone/laptop at all. It just sends over a code. The device only sees one code and nothing else.
This is also why a user can get a new phone and and just tap the key to the new phone and truck on. Magic.
When a user drops their Google Authenticator phone in the toilet however... bad day.
Yes, I'm clear that the attacker in this scenario doesn't get your TOTP secrets. If your primary goal is to protect your TOTP secret, I see your point. My problem is, my goal is to protect my actual account. I kind of don't give a shit about my TOTP secret, because Google will give me as many new TOTP secrets as I ask it for, but I only have the one account. If the device I'm securely generating a TOTP secret for is compromised, I'm going to feel pretty silly doing a security theater dance with my Yubikey as my attacker steals my cookie and locks me out of my Google account.
Not all services do this, and Google does no do it all the time either.
Still, I see no reason not to take the super easy low-hanging fruit to reduce attack surface when you can.
If someone gets remote access to your device it is a very bad day, but you -can- have damage control and a clear picture of what they had access to and what they did not.
If the attacker roots your phone and it has your unlocked password manager on it and google authenticator with all the 2fa secrets... well now they get the entire farm, including for services you don't have active cookies for.
Hardware tokens are not magic, but they are a very useful tool and if we combine enough tools we make the life of an attacker that much harder.
Let me simplify my point: Whether or not the TOTP secret is on the smartphone, encrypted or not, or sent to it from another device, is the wrong attack vector to optimize for.
Getting mainstream users en masse to consistently and correctly use any 2fa is a win.
Furthermore, you're moving the goalposts a bit by using the Yubikey in this scenario. So sure, if someone compromises your phone they don't compromise the Yubikey, but 1) how certain are you that your Yubikey is safer than a modern iPhone or Android model with the crypto and security engineering that entails and 2) how certain are you that accessing your iPhone's filesystem or execution state does not bypass this whole dance entirely?
For you, the minimal security gains might outweigh the usability costs if you know what you're doing. But a hardware token for most people, as the technology currently stands?
By moving secrets to very simple easy to reason about devices we get substantial reduction in attack surface.
Also I have helped deploy these to several dozen people, taught workshops etc. It is no harder than teaching people to use Google Authenticator, but lower attack surface.
Use U2F where you can and when you must fall back to TOTP at least you can promise an attacker does not get a free pass to genreate codes whenever they want which is something.
I think ya might be able to argue that if you're going to add friction (e.g., Yubikey) you're also creating a great senses of seriousness. That sense of seriousness is seriously lacking.
All that said, the UN + PW idea is too weak. We need something that's up to the threat AND is also appropriate to the risk of loss. Best I can tell, as a general mainstream rule, we're not even close to that. It's 2017? Really?
The attacker who gets access to the filesystem of your
phone can almost certainly defeat any "encryption" a TOTP
authenticator would use to protect secrets
[1] https://news.ycombinator.com/user?id=tptacek [2] https://latacora.com/
If you have a need for hardware tokens, use them end to end. Using a hardware token and having a less secure backup method means you are only as secure as that less secure backup method.
So, when you have the token handy, you use it, and you're not exposed to phishing. When you don't, you use the mobile app, and you're exposed to phishing (but not to weak passwords and breaches in sites). It's not complicated, unless you think the token does more than it really does for your overall security.
TOTP is a mess in regard to phishing but if we have tools to avoid some of the problems while we are stuck with it, I feel they are worth mentioning.
Particularly for people savvy enough to purchase hardware tokens for personal use.
One nitpick: the guide says "If you're curious why it's important to not have a phone number on your account, see the security key FAQ", but the linked security FAQ doesn't actually appear to say why it's important.
The answer is that SMS is not a secure second factor (it's easy to hijack and eavesdrop on), and in some cases when you give a service a phone number, it becomes possible to take over the account with just control of the phone number.
It would be a reasonable backup in place of (or in addition to) Google Authenticator.
[0]: https://blog.coinbase.com/on-phone-numbers-and-identity-423d...
How in the world is a random guy supposed to do this sort of thing? Anyone have any tips for people who get into these situations and who aren't already BFFs with C-level executives of phone companies or something like that?
Would be interested in seeing contrasting views though!
The real answer for "why not a smartphone app" is "because code generators are just as phishable as passwords". In the real world, that's how people are being compromised, not by elaborate phone exploit pivots but by phishing pages. It also speaks to why phone authenticators are acceptable backups to tokens.
The real answer for "why not SMS" is "because both teenagers and intelligence services can get a phone number redirected; your phone number is not your phone."
Obviously, you don't PIN-lock a U2F token; the answer to "what if it's stolen" is "whoever stole it probably doesn't have your password, which they'll need in order to use the token, so if your token is stolen remove it from your account and then fish $17.99 out of your couch cushions and buy a new one".
No matter how much you protect the secret though, not getting phished is left to the hopefully paranoid user, which is for sure not ideal, but we are probably years out from TOTP being replaced with U2F for most sites.
TOTP via hardware tokens is a stopgap.
Great comments though. Will update to reflect them.
The idea behind the U2F/TOTP stack is to minimize your exposure to phishing attacks and at the same time minimize (to practically zero) the odds of you being locked out of your account. It accomplishes that nicely, which is why most of the other experts we talk to have U2F/TOTP/backup-codes as their Google 2FA stack.
The only one I can generally suggest for most people right now, in spite of it being closed, is the yubikey 4. Mostly because it can be configured to require a physical touch for each operation. Something a remote attacker can't do.
I started putting some comparisons down here: https://github.com/lrvick/security-token-docs/blob/master/De...
In particular an android phone that might not have the latest version of android on it.
Also for situations where not only do you access your gmail from your phone but also your google authenticator app is installed on it.
I'm actually using Outlook as my e-mail client now. It's surprisingly snappy for my minimal needs. Maybe I should switch to iCloud for e-mail, and aim for the trifecta...
That said, I personally would never own an iPhone and I'm happily bliss on my Note 3 with Android 4.4. But I don't access my mail, bank, or anything else sensitive on the device. For me it is no more than a phone, camera, and Anki interface!
An iPhone is so much more secure than any laptop that it more than makes up for the small drop in second-factor security.
The Yubico are probably the best key chain candidate. No one wants to trust their key to a weak nylon thread.
You can also set up a Google account to use more than one U2F key.
As for Google 2FA, I think Google caused a lot of confusion by how they set up the Google Authenticator app. Always opt for the text generator codes instead of a barcode. You can then use the code to use on a second Google Authenticator app on another device. Google at one time stated that you could only set up 2FA on a single device, which makes most users leary as one could lose his or her phone.
I suppose you could always take a photo of the QR code and then rescan that. Text seems simpler.
edit: Anyone else remember this behavior? Old version? Browser specific?
Edit: maybe I should have explained my position. There are a few security issues with rooting a phone, e.g.:
- rooting usually requires unlocking the bootloader. Once it's unlocked, anyone can flash or boot a custom recovery and modify your system partition. Enrolling your own keys in the recovery and re-locking the bootloader, while possible, is an undocumented and complex process that just about nobody uses, see https://mjg59.dreamwidth.org/31765.html . You're also screwed if a system update replaces the recovery. Once the bootloader is unlocked, anyone with physical access to your phone can mess with your system in malicious ways.
- it circumvents the system's permission model. A malicious app that tricks the user into granting it root rights (maybe for a legitimate reason) could access information it shouldn't have, install a keylogger, etc.
clickable link: https://amzn.com/dp/B00WIX4JMC
>If you're curious why it's important to not have a phone number on your account, see the security key FAQ.
but this is not explained in the FAQ. I've never heard about this before, why is this important?
U2F will be superseded by Web Authentication [0] that includes U2F and will be supported by all major browsers. Edge includes draft spec API that uses TPM to store keys.
https://addons.mozilla.org/en-Us/firefox/addon/u2f-support-a...
As an alternative to a second key as a backup, you can always keep a set of printable backup OTP tokens offline in a safe etc, ideally encrypted.
As for the browsers: Chrome/Chromium works fine. Firefox has an addon that adds security key support[0]. Unfortunately, this addon has a bug which causes high CPU load[1]. Firefox is also working on adding the native support for this, and I think that their ETA is somewhere in the second half of this year to get this thing to work natively. Unfortunately, even with the U2F addon on Firefox, you still won't be able to use it for Gmail, since Google hardcoded its browser to be the only one with U2F support, so you're going to have to change your user agent in order to use it, or default back to your second method of 2FA (Google Authenticator or something of the sorts). I have no knowledge about the U2F status on Safari and Edge.
As far as I was able to discover, the only service that didn't hardcode Chrome as being the only browser at the moment with U2F support is GitHub, and using YubiKeys with Firefox + U2F addon on GitHub works without any issues (other than the occasional high CPU load that I've already mentioned).
I wrote a short article on my blog about Yubikey usefulness for my usual setup about a year ago[2]. Things changed slightly to the better since then, but not by a lot.
[0] https://addons.mozilla.org/en-US/firefox/addon/u2f-support-a...
If you have a phone with USB Type-C and a Yubikey 4c you can just plug it in direct.
WebAuthentication will be supported in all major modern browsers [1], it just takes some time to implement.
[0]: https://bugzilla.mozilla.org/show_bug.cgi?id=1065729#c254
"If you're on a newer mac, you may have to use a USB adapter, like an animal"
Too late, Google now has it and can correlate my profile with other sources. There's literally no other reason why Google doesn't let you enable 2FA without a phone number.
I wish I didn't have to choose between security and privacy.
I'll take the Pepsi challenge with anyone on Google bashing, but I think this one is not fair.
It does hold for Facebook, though :-)