CSS Is Now So Overpowered It Can Deanonymize Facebook Users (bleepingcomputer.com)
An anonymous reader writes: Some of the recent additions to the Cascading Style Sheets (CSS) web standard are so powerful that a security researcher has abused them to deanonymize visitors to a demo site and reveal their Facebook usernames, avatars, and if they liked a particular web page of Facebook. Information leaked via this attack could aid some advertisers linking IP addresses or advertising profiles to real-life persons, posing a serious threat to a user's online privacy. The leak isn't specific to Facebook but affects all sites which allow their content to be embedded on other web pages via iframes.
The actual vulnerability resides in the browser implementation of a CSS feature named "mix-blend-mode," added in 2016 in the CSS3 web standard. Security researchers have proven that by overlaying multiple layers of 1x1px-sized DIV layers on top of iframes, each layer with a different blend mode, they could determine what's displayed inside it and recover the data, to which parent websites cannot regularly access. This attack works in Chrome and Firefox, but has been fixed in recent versions.
The actual vulnerability resides in the browser implementation of a CSS feature named "mix-blend-mode," added in 2016 in the CSS3 web standard. Security researchers have proven that by overlaying multiple layers of 1x1px-sized DIV layers on top of iframes, each layer with a different blend mode, they could determine what's displayed inside it and recover the data, to which parent websites cannot regularly access. This attack works in Chrome and Firefox, but has been fixed in recent versions.
Umm Facebook is soo overpowered that they have soo much information COUPLED with poor coding that permits leaking this infomation...
What's the big deal? CSS isn't the problem, browser's shoddy implementations is/was.
”This attack works in Chrome and Firefox, but has been fixed in recent versions.”
In other words, this is a clever exploit of a bug - not a fundamental issue with CSS. The rest is FUD.
#DeleteChrome
CSS can't magically make AJAX calls to a service API and rewrite the service code to return private information. The devs are probably re-using an API call that returns a ton of data just to pick out 1 or 2 fields to display.
If you send it to the client, it's no longer a secret. One of the mobile carriers would send back this huge JSON object containing everything about you on a simple account details page (name, address, etc). The object contained a ton of "private" information like your credit rating, SSN, type of customer, and even the "comments" field used by Customer Service.
Get it now. Block all CSS across the board.
I have never seen an implementation of iframes that didn't cause problems or just plain suck. Browsers should just stop supporting them.
and if I don't use Facebook?
oh it's fixed too?
clickbait!
The headline should read Facebook security is so underpowered that CSS can deanonymize users.
Another day, another reason to stay away from Facebook.
Mimetics Inc. Twitter
No more adding features to HTML5/CSS/JS. They are only being used for things like tracking, spying, malware and crypto mining.
This attack works in Chrome and Firefox, but has been fixed in recent versions.
So then it _can't_ be used to deanonymize Facebook users.
Why is this a problem then?
this is moronic. if Facebook is leaking private data to the client browser, this is NOT a CSS problem. what an insipid and misleading headline.
i could live a little longer in this prison
That made me laugh.
Even if it was still working, it,s not like I ever gave facebook a single real information. They don't have my real name, picture, phone number, real email, etc...
/. green, too. css needs a nerf, too op.
captcha: styling
And don't use Facebook.
Every day I clear my data. Everything is wiped clean and I start fresh. Yes, advertisers could deduce about me with each daily trek through the Net wilderness, but I also have uMatrix which blocks other forms of advertising and intrusive behavior so they have to work for it.
Regardless, since I don't see whatever it is they're peddling, it's no big deal. It costs them money so I'm happy.
So why is this story blue?
CLI paste? paste.pr0.tips!
Just delete your account already and flush its cookies.
I know it doesn't really delete any as Zuck is confirmed liar, but at least don't give him any excuse to have your data.
Hopefully the EU GDRP is the first step to wipe this obscenity off the face of the earth.
It sounds like this is yet another case of JavaScript having access to a side-channel that should never have been possible - in this case, being able to determine how long it takes the browser to render the page.
Of course, there's also the eternal problem of permitting pages to embed access-controlled content from other domains in the first place (rather than, e.g., tying all cookies to the URL bar domain.)
CSS is indeed overly complicated, and that's a problem too, but let's put the blame where it belongs.
3PRB can block CSS images.
You think this is bad, try a password keylogger implemented purely as CSS (no javascript):
https://css-tricks.com/css-key...
The real vulnerability in both this and the article example is allowing 3rd party code injection. If you can't trust the source of the code, the language being used doesn't really matter. There will be ways to abuse it.
I'm out of my mind right now, but feel free to leave a message.....
So very, very blue!
Are browsers like Opera and Edge still vulnerable then? I can't seem to find anything on that.
Rendering blur effects on fonts and measuring the time to render to guess letters, checking for expected remote case to expose surfing history ... The stuff web hackers can do is pretty amazing. If you're in web development and are looking for a reason to switch to sheep farming just visit a web hacker conference. You'll come home crying.
We suffer more in our imagination than in reality. - Seneca
be a problem if you are using privacy plugins that already block single pixel tracking bugs. The attack ALSO REQUIRES, you guessed it, Javascript. So, it's not a pure CSS attack. See https://github.com/evonide/mis.... These blokes didn't test against a rig with any privacy plugins.
Here's the real question: they're running a timing attack on how long it takes to render a pixel outside the parent element they're providing the style for. They specifically attack an iframe from Facebonk that shouldn't be able to receive styling from their CSS script unless they load at the same priority as Facebonk itself. So, this is a driveby attack that requires the FBonk to maintain your logged in state based on cookies. Otherwise, their little iframe to facebook isn't going to display any information.
So, they can't really hack FB, but it's an interesting attack. Surely a bug.
And one more thing.... this is a timing attack, right? Why are the browsers giving out time accurate to the millisecond? This sort of thing makes timing attacks possible? What possible purpose could there be in handing it out such accurate time to Javascript? Can't we just go with 0.01 (0.0254 metric) seconds resolution?
CSS tracking's nullified via APK Hosts File Engine 2.0++ for Linux. It protects you vs. tracking/ads/malware & speeds you up 2 ways (ad & script blocking) & DNS requestlog tracking via locally resolved favorites (avoids dns security issues too & dns down).
Vs. Script it's faster (kernelmode vs. usermode + starting 1st) than NoScript.
* Linux version's 10x FASTER vs. my Windows model (done in Delphi XE2-4 32/64-bit) via FreePascal + Lazarus 1.8.2 - speed gain's better underlying architecture (non-visible stringlists ONLY, Windows one did a mix of 'em + visible grids (had messagepass overhead I underestimated)).
APK
P.S.=> It's SO fast/accurate I'd race ugly inferior shellscripts (others' code merely USED in script) OR native tty term exes for same purpose (w/ same dataset) & I'd win - my reverse DNS resolution alone = 10x faster (IF scripts even do it, most don't) as ping in Windows/Linux are (& I "do the impossible" PING on Linux MINUS Root)... apk
Millennial alert. It's just a tool, all tools can be utilized To wreak havoc, it doesn't imply inherent 'power'. That's your generation's biggest problem in life: your parents never taught you what real empowerment even looks like. Worse, they taught you to respect its opposite (that would be 'victimhood' for the less savvy members of the class). Give us a break. This isn't the worst aspect of Facebook or other social media, not by a long shot. It seems to me that no matter how old millennials get, everything they observe and share is essentially at root a cry for yet another safe space. Grow the fuck up.
>> CSS ... Can Deanonymize Facebook Users
That's impossible.
Facebook users are not anonymous to begin with.
I've commented to a mathematical friend more than once that computer science is mathematics, plus the assumption that time exists. (This also explains why I'm LISP-boner impotent. LISP is computer science, ++delay, minus the assumption that time exists; the user sees time, while the programmer doesn't—what's not to like?—but I still don't get the happy hardness.)
Moral of the story: fear the clock.
Do not fear napkin Turing-complete, CSS Turing-complete, nor LISP Turing-complete. (Turing-complete happens by accident at least once out of every nine innings of billiard-table HO-gauge NAND-gate pick-up-sticks.)
Perhaps what we need is a degraded system timer.
Ideally, the local mean would wander somewhat slowly on a fractalish time scale, only minimally convex around the extremes so as to stay within a +/- 30 second deviance specification for 99.8% of all samples. Ideally, the estimate of the mean would converge considerably more slowly than sqrt(N). But I don't know my thick-tailed distributions well enough to say what that would look like as an actual thing. You also don't want the difference between step changes to be small, on average; and you don't want the locations of the step changes to occur on precise, minute boundaries, either (duh!) In fact, I think sloppy-clock would return an ascending integer sequence, but the wall-time duration of each distinct integer interval (of minute-ish duration) would be unpredictable, as described.
My math is feeble enough that I can't even prove that my sloppy-clock as roughly stipulated even exists in practice, but let's assume it does.
Then you need to implement a security ring where the best clock available is sloppy-clock—and stuff all foreign scripts in there. Yes, plugging time leaks from the outside world in a sophisticated API is hard. True mathematicians need not apply (i.e. LISP won't help you in this endeavour, not even a little bit).
By avoiding capacitors (condensors) von Neumann's IAS computer could be frozen and single-stepped, or run at any frequency you desired, until the internal bit signals themselves became unstable. (Some of these early designs were actually asynchronous and self-timed.) Effectively uncoupled from the real world, such a machine has no ability to introspect the duration of its own operations—unless you screw up, and give it an actual wall clock or cycle-clock or global operation-count API (the second case is only possible with synchronous designs).
Uncoupled computing (Internet 404) is not popular under the modern CSS paradigm, so you do probably have to at least make a concession for sloppy-clock (which dingbat users can upgrade to precise-clock if it bothers them that their ESPN scoreboard page refreshes aren't entirely concurrent with the real world; it would also suck for implementing chess clocks; but not, strangely, for anticipating when a soccer game will officially end).
Anyways, this whole proposal is a massive research project.
I'm merely pointing out that computer science is merely mathematics—right up until time begins.
Von Neumann's early IAS computer didn't even have (internal) time. (That's because they had more than enough problems to deal with, already, without scoring an own goal.) Interestingly, Turing specified hardware random number generation from the get go, on purely formal reasoning about the space of available computation. Turns out, precisely measurable operational elapsed-time is ultimately more insidious (under promiscuous interconnection) than nondeterminacy. (A promiscuous web page being any web page bearing more than one cookie, or related code artifact.)
Maybe time does not fly like an arrow as described in its early scouting reports—but it certainly does leak (across code-execution trust domains) like a bat out of hell.
In my browser the headline is blue. What does that imply?
THIS IS FACEBOOK!!!
See subject: It's MUCH faster + more efficient now on Linux (rethought part of it). 1st link sheds more light on it https://www.google.com/search?client=ubuntu&channel=fs&q=%22APK+Hosts+File+Engine%22+and+%22start64%22&ie=utf-8&oe=utf-8/ & it gives users of it greater speed/security/reliability, natively, minus "Bolt-on-'MoAr'" ILLOGIC-logic + less complexity (& bugs/security issues) + faster using what you already have in a 45++ yr. PROVEN subsystem in the IP stack itself...
* Soon to be ported to FreeBSD/PC-BSD (trueOS) & Mac OS X too!
(FACT: No SINGLE "so-called 'competitor'" of it does as much for much less natively - period)
APK
P.S.=> If that's not enough? Ask any questions you like, I'll do my best to answer... apk
[TFA] security researcher has abused them
Hey wait. This is a tech site.
How about leveraged them, or even used them?
Imagine non-tech readers. It's a gimmick to trigger one of those "there oughta be a law" responses. THIS is how we get laws against the sale and possession of radio scanners that can tune in unprotected police communications. And instead of forcing police to upgrade their equipment, they get a bonus opportunity during traffic stops to pretend that their K9s 'signalled' the presence of an illegal scanner. Which in turn, encourages farmers to grow smaller potatoes.
<blink>down the rabbit hole</blink>
"The language of the mystic arts is as old as civilization (truthtables behind boolean logic are, foundation of these machines). Sorcerors of antiquity called the use of this language spells but if that offends your modern sensibilities, you can call it a program: We draw energy (information) from other parts of the multiverse to make shields (no weapons> to make MAGIC...
* FROM Dr. Strange ala https://www.youtube.com/watch?v=PN6JFVQfwp8/
APK
P.S.=> In a very REAL sense, that's what I'm up to & I couldn't put it ANY BETTER than that... apk
See subject & You're nothing but a jealous do-nothing "ne'er-do-well" that WISHES he was me. You can't justify stalking me & IF I ever found out who you are + WHERE you are? I'd pound the fucking SHIT out of you, you disgusting waste of life PUSSY projecting your own faults onto me & failing as always (it's all you've ever done - fail).
* ... & you KNOW it + show it...
APK
P.S.=> Why won't you tell me your name, address, and phone number so I can verify WHO you are & come pay you a visit in person, pussy? We all KNOW why (you are a pussy)... apk
See subject: You're just a lazy psychotic do-nothing "ne'er-do-well" loser that stalks me on /. via your unidentifiable anonymous posts - big accomplishment on your part (lmao - not).
* You're a sick in the head little pussy bitch - no questions asked.
APK
P.S.=> Why not meet me face to face & we can settle this by my smashing your teeth out of your jaw - ok? apk