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Chrome lets hackers phish even 'Unphishable' Yubikey users
- christefano 9y agoWell, that's ironic. Just yesterday I subscribed to a magazine that offers a Yubikey as a free gift. The magazine? Wired. It looks like this vulnerability is limited to Chrome at the moment. Good to know if using Chrome (or even Epichrome for SSBs) when doing things like online banking.
- crispyporkbites 9y agoThis is the attack: > If a victim logs into a fake Google site, the phishing site passes on their username and password to the real Google login page. Then the spoofed site passes back Google's request for the user's U2F token and collects the Yubikey's unique answer, all via WebUSB. When that answer is then presented to the real Google site, the attackers gain access to the victim's account. So basically they are somehow able to trick the yubikey neo into accepting a challenge from a different domain, by using the webusb API. Reading further: > The technique would only work with U2F keys that offer protocols for connecting to a browser other than the usual way U2F tokens communicate with a computer, known as the Human Interface Device or HID, which isn't vulnerable to the attack. The Yubikey Neo, for instance, can also connect via the CCID interface used by smartcard readers > An assumption was made by Chrome that all U2F is HID, which doesn't hold for the Neo, whereas Yubico made an assumption that USB will never be accessible by web pages directly So: - Don't use a Yubikey Neo anymore - Don't use Chrome - Don't use U2F because FireFox doesn't support it - Never use your yubikey because hardly anything supports it Sigh
- m-p-3 9y agoHopefully better support for U2F devices is on the way at both the browser and website level. I wish more websites offered the option to use it.
- ilikepi 9y agoPresumably you are referring to WebAuthn[1]. I am optimistic that this will lead to better browser support, and consequently better website support. IIRC it's expected to reach Firefox stable in the May release. Hopefully the various sites that currently only support U2F in Chrone will move to this new standard. [1]: https://www.w3.org/Webauthn https://www.w3.org/Webauthn
- SahAssar 9y agoOr disable webusb
- Ajedi32 9y agoOr just don't click "Connect" on the USB access permissions prompt when it pops up. Unfortunately though, as with any phishing attack, this flaw is most likely to be effective against uninformed users, and those users are the least likely to take proactive measures to protect themselves beforehand. Fortunately: > "We will have a short term mitigation in place in the upcoming version of Chrome, and we're working closely with the FIDO Alliance to develop a longer-term solution as well."
- crispyporkbites 9y agoWhat kind of uniformed user uses a YubiKey? I supposed you could trick them by saying that the login process has changed and they need to enable WebUSB to let their YubiKey work
- jessaustin 9y agoThis seems to indicate that DoD uses them. Perhaps it's mostly contractors, but there are probably some liaison-type uniformed people too: https://www.yubico.com/about/reference-customers/department-defense/ https://www.yubico.com/about/reference-customers/department-...
- x0x0 9y agotqbf, pinboard, and zeynep are handing them out to journalists. There is an enormous need for some solution resistant to users who aren't good at identifying legitimate vs phishing sites. U2F as it stands is the only practical and deployed solution to that problem. It's infuriating that chrome broke this security promise to compete with microsoft.
- tedunangst 9y agoUninformed users who have an informed friend looking out for them but not looking over their shoulder every single minute.
- mfontani 9y ago> - Don't use U2F because FireFox doesn't support it It does! Open about:config and switch security.webauth.u2f to true. It'll Just Work. I've in the recent past modified a barebones Perl webapp to try and understand U2F better, see https://u2fdemo.darkpan.com/ https://u2fdemo.darkpan.com/ I've been able to log in / use U2F from: * FF on Windows and OSX * Chrome on Windows, OSX * Chrome on Android using either a OTG cable for a U2F USB key, a Bluetooth U2F key, and a NFC U2F key (works if you install Google Authenticator) * Unfortunately, not FF on Android as I can't find how to enable U2F there yet :/
- crispyporkbites 9y agook scratch that, use firefox then but still hardly anything supports U2f :-(
- Slansitartop 9y agoNot everything supports U2F, but plenty of things do, many of them high value services: http://www.dongleauth.info/ http://www.dongleauth.info/
- mondoshawan 9y agoIt works, but only partially, and is still very very broken, which is why it is disabled in the first place. See also this bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1065729 https://bugzilla.mozilla.org/show_bug.cgi?id=1065729
- phyzome 9y agoNonsense. It works fine on Github, Fastmail, Gandi... it doesn't work on Google because Google uses a different spec. That bug is about making Firefox compatible with the variation that Chrome/Google uses.
- uiri 9y agoThat bug mentions that Facebook is also broken. I am kind of surprised that the sites you mention can implement the spec correctly but Facebook and Google can't.
- skybrian 9y agoMore importantly: "the phishing site would also have to ask the user's permission to enable WebUSB access to their Yubikey, and then tap the physical button on the key." So don't do that. It would be nice to know exactly what this dialog looks like, but it seems low risk?
- pfg 9y agoConvincing users to grant access to a USB device when they're attempting to log in to a service using said USB device sounds like something that would work more often than not. We wouldn't need phishing-resistant authentication methods if humans were good enough at making those kinds of decisions.
- stevehawk 9y agoI have to admit that in all of my use of my Yubikey Neo in Chrome I don't recall ever being asked for permission to access the device. Firefox hasn't asked either.
- pfg 9y agoI'm not saying that you need to grant any kind of permission in order to use U2F tokens, but rather that a user thinking "I want to login to Google" and "I need to use that USB key thingy to do that" is quite likely to accept a prompt that requests access to the U2F device.
- stevehawk 9y agoSorry, I guess what I was getting at is that in hindsight I'm surprised no browser ever explicitly asked me for access to the Yubikey or told me why it needed, I've just blindly trusted it because of the few sites I use it with. On the other hand, it's basically functioning as another keyboard device and not a special USB device so it shouldn't be that surprising, right? (serious question)
- Buge 9y ago>So don't do that. How about you tell users to simply not enter their password into phishing sites? When users want to do something (sign in) and there are instructions on the page telling them to do something (enter password or accept usb) then the users will do it.
- Sir_Cmpwn 9y agoThe existence of WebUSB is awful. Why anyone ever thought it was a good idea to let JavaScript touch your USB devices is beyond me.
- emilfihlman 9y ago...Wat. What you said is wrong on so many levels.
- omni 9y agoThis comment added nothing, in the future please consider offering substantive criticisms.
- Ajedi32 9y agoIt's simple: allowing sandboxed code to request limited access to a USB device is more secure than having users install native, unsandboxed code with access to everything on their PC.
- tedunangst 9y agoAssuming the sandbox works. If the sandbox is porous, the attack surface balloons from apps I choose to install to every link I click.
- Ajedi32 9y agoNot every link you click. Only sites that you grant access to the necessary attack surface. The Web USB API can't be attacked by sites that you haven't granted access to it.
- codedokode 9y agoWhat if that privileged website has XSS vulnerability?
- 9y ago
- ravenstine 9y agoI didn't even realize web USB was a thing now. I remember it being talked about, but I must have missed the HN conversation when Chrome implemented it. So does Chrome ask for permission to allow USB access? Or maybe there's something about this I'm not getting.
- pfg 9y agoThere is a permission prompt, but it's fairly easy to convince users to accept it during a login attempt when they're expecting their USB U2F device to be used.
- Shoothe 9y agoIt's surprising that this works. Last time I checked WebUSB the device would have to have a descriptor allowing its use via web page effectively white listing what can be used on the web.
- Ajedi32 9y agoLooks like they changed it: https://wicg.github.io/webusb/#attacking-a-device https://wicg.github.io/webusb/#attacking-a-device While I understand the reasoning behind that move, I'm not sure I fully agree with it. I don't think users will necessarily understand the implications of granting a site access to a device that wasn't designed with attacks from malicious code as part of its threat model. At the very least, the wording on the permissions dialog should be changed to indicate that the user is granting the site _full control_ over the device they're connecting it to.
- deleted 9y ago[deleted]
- tyler_larson 9y agoIt sounds like the report glossed over a rather important bit of ux: If, when logging in, you see a big modal dialog asking if you want to grant webusb access to the site, then DONT select your yubikey out of the list of connected USB devices and click "Allow". As long as you can convince yourself to avoid taking that particular unusual action, it sounds like you're fine.
- tinus_hn 9y agoIf the user thinks the site is Google it’s not that strange they’d give them access to the key.
- decko 9y agoYou can disable CCID, does that not solve the issue?
- cpburns2009 9y agoIt's almost as if browsers are slowing reinventing Java applets while ignoring all of the security implications that go along with it.
- Santosh83 9y agoThey're slowly inventing operating systems, complete with hypervisor technology, with all the gargantuan complexity that it implies, to please big business that wants the client OS to essentially become obsolete.
- throwaway23424 9y agoThe web browsers are so much more secure than what we had before (just accepting executable binaries from other people), so I look at this as a way forward.
- cpburns2009 9y agoI'm not that confident. Browsers blindly accept and execute whatever they receive. The more features that get added, the larger surface there is to exploit. A case in point: WebUSB as mentioned in the article.
- Ajedi32 9y agoThe nice thing though is that, although the added attack surface is there, its not really accessible to web pages until a user grants the necessary permissions. Not really all that different from telling users to execute a native app in that respect. In this case it's not even an exploit really; more like social engineering. (Tricking users into granting the phishing site unrestricted access to their Yubikey, then using that access to trick the user into authenticating a login session for the phishing site.)
- codedokode 9y agoImageine if there is an USB device with new Chrome WebUSB driver (which has necessary permissions) and then vendor's website gets hacked.
- ewindisch 9y agoThe Yubikey is great and has uses outside of U2F, which I've never had much faith in.
- LethargicStud 9y agoI'm unclear as to how this would work in practice. Chrome supports U2F out of the box, so getting a big weird pop-up asking to access your USB device, you'd at least be suspicious. Upon registration, the server also collects a nonce, which is used for verification[0]. The attackers would need to get that nonce from the site. Hopefully, the site disables CORS so a phishing site cannot request a challenge. Lastly, on Linux (I know, a minority), you need to make an entry in rules.d[1] to even allow Chromium to access USB devices. I can see how this potentially maybe could catch someone, but I don't see it as much of a risk. [0]: https://blog.fastmail.com/2016/07/23/how-u2f-security-keys-work/ https://blog.fastmail.com/2016/07/23/how-u2f-security-keys-w... [1]: https://developers.google.com/web/updates/2016/03/access-usb-devices-on-the-web https://developers.google.com/web/updates/2016/03/access-usb...
- Ajedi32 9y agoPart of the problem is that, assuming you didn't know much about how U2F works, it seems pretty natural for a site to request access to your YubiKey in order to use it to authenticate you. While its obviously not a total solution, I do think that maybe the permissions prompt should be a bit more scary: https://developers.google.com/web/updates/images/2016-03-02-access-usb-devices-on-the-web/usb-device-chooser.png https://developers.google.com/web/updates/images/2016-03-02-... I'd rephrase that to something more along the lines of "example.com wants full control of". Maybe with an option for device manufacturers to opt-in to support for WebUSB, allowing for protocol enhancements to improve security and a less scary permissions prompt.
- Buge 9y agoCORS is irrelevant. >The attackers would need to get that nonce from the site. The attackers have their own machine with a browser running on it that visits the real site and gets the nonce, then hands that nonce to the victim to be signed by their key.
- valkum 9y agohmm. I assumed U2F does not protect you from phishing. It just adds a second layer of protection to your account. Protecting you from credential theft. U2F antiphishing stuff implemented by chrome is just a neat little extra. Is this behaviour of checking the origin in the spec?
- tedunangst 9y agoThe supposed ability to tap the yubikey button even on phishing sites and not actually give up working credentials was like the selling point.
- Ajedi32 9y agoYes, preventing phishing by only sending credentials to the appropriate origins is a very important part of the spec: https://fidoalliance.org/specs/fido-u2f-v1.2-ps-20170411/fido-appid-and-facets-v1.2-ps-20170411.html https://fidoalliance.org/specs/fido-u2f-v1.2-ps-20170411/fid...
- andybak 9y agoDidn't lots of people suggest this kind of thing as a potential issue when WebUSB was first mooted?
- exabrial 9y agoI wish channel bound tokens were mandatory in the u2f spec, or a browser key was part of the auth request to the token, for exactly this reason. U2f is "optionally" unphishable.
- eximius 9y agoFIDO discussed this on their site. It's optional so corporate firewalls that perform MITM can continue to work with U2F.
- Buge 9y agoHow would that help? Couldn't the webusb simply lie to the u2f device about what the channel is?
- exabrial 9y agoGo take a look at token bound channels. It sure could but it'd be completely useless to do so.
- Buge 9y agoI know a bit about token bound channels. But the u2f device only talks to Chrome via usb. So anything that the legitimate chrome could say to the u2f device (negotiating tokens, channels, etc) can now be done by the attacker via webusb. So I would think the attacker can get the u2f device's signature on the attacker's channel. It should be just as if you unplugged your u2f device from your machine and plugged it into the attacker's machine.
- nimbius 9y agoU2F != OTP, which is Yubikey 4. For some reason the FIDO alliance decided they didnt want OTP. Yubikey 4 allows openPGP keys as well as OTP Yubikey functionality, making it half HSM/half token. the FIDO keys offered by Yubi only do asymmetric cryptography.
- Buge 9y ago>For some reason the FIDO alliance decided they didnt want OTP. OTP is regularly phishable, not requiring any webusb. Before this webusb attack, u2f was unphishable.
- codedokode 9y agoWhat is the usecase for WebUSB? Here [1] someone from Google suggests vendors should write device drivers in Chrome HTML and Chrome Javascript. Please don't. Or (my assuption) it might be for devices that cannot work without browser and network connection. [1] https://developers.google.com/web/updates/2016/03/access-usb-devices-on-the-web https://developers.google.com/web/updates/2016/03/access-usb...
- Ecco 9y agoWell, we found it really, really useful! https://www.numworks.com/blog/webusb-firmware-update/ https://www.numworks.com/blog/webusb-firmware-update/
- codedokode 9y agoNext step will be devices that cannot work without Chrome, network connection and "anonymous" "telemetry" for the purpose of "improving customer experience".
- makomk 9y agoYeah, the great thing about WebUSB is that it can easily be used to upgrade devices to new firmware with new features. For example, suppose that some end user's USB device lacks the ability to act like a USB Rubber Ducky and inject malicious keystrokes in order to compromise their machine. WebUSB allows a clean, easy way to fix that remotely. WebUSB terrifies me.
- anfilt 9y agoA website should never access to usb devices with just an allow prompt. Imagine taking control of a usb mouse or keyboard... You could then just take control of the machine...
- basicplus2 9y agoIt seems like i am often reading about reasons why Not to use Chrome.. Are there any good writeups about security of different web browsers? is Chrome a real issue?
- Sylos 9y agoI can't imagine that there would be such a writeup. Even just trying to understand the security framework of one browser is a gargantuan task. As for Chrome being a real issue, some points off the top of my head: - Its extension store breeds out malware in regular intervals (feels like there's headlines about that at least every other month). - Pretty bad autofill exploit that was left unfixed for years: https://github.com/anttiviljami/browser-autofill-phishing https://github.com/anttiviljami/browser-autofill-phishing (Might've been fixed in the past year, I haven't checked, but I doubt it.) - Chrome Sync is not end-to-end-encrypted without the use of a second password, which effectively means that it is unencrypted for 99.9% of Chrome users. Google also actively uses this data, weaving your browsing history into the profile that they keep of you. So, if they ever have a data leak, a lot of data is going to come from people using Chrome, too. The NSA/CIA/FBI also tap into this data, possibly using it for cyber war attacks, so if you live in a country other than the USA, you're making yourself a prime target and an easy target by inputting this data through Chrome.
- ezoe 9y agoAt this rate, you should rather write down the passwords in the paper and stick it to the computer. Sure, it's vulnerable to the man behind your back. But if such threat exists, you shouldn't type your password anyway.
- vanadium 9y agoThe Ledger Nano S also uses WebUSB to sign into the Stellar (Crypto) dashboard and can be used as a U2F authentication device. I'm curious (assuming even) that it could be subject to this exploit?