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Flash Cookies, a Little-Known Privacy Threat
Wiini recommends a blog posting exploring Flash cookies, a little-known threat to privacy, and how you can get control of them. 98% of browsers have Macromedia Flash Player installed, and the cookies it enables have some interesting properties. They have no expiration date; they store 100 KB of data by default, with an unlimited maximum; they can't be deleted by your browser; and they send previous visit information and history, by default, without your permission. I was amazed at some of the sites, not visited in a year or more, that still had Flash cookies on my machine. Here's the user-unfriendly GUI for deleting them, one at a time, each one requiring confirmation.
1. Flash supports local shared objects, not "cookies". Cookies are submitted back to the server. Shared Objects are bits of storage available to movies from a particular domain. They must explicitly submit the information back to cause an information leak.
2. Using shared objects to save browsing history is dumb. If you wanted to do evil Flash tracking, use a unique id that you can look up on the server side.
3. You can delete and/or restrict the contents from inside a Flash movie. Use the right-click menu in Flash to access settings and set the storage level to 0 bytes. That will wipe everything out. It will also force Flash to prompt you every time it wishes to save something to disk.
4. This was added in Flash 6, which was released back in 2002. Since then, it has been used by a variety of Flash applications. Many of which you probably use every day. From saving your progress in your favorite Flash game to remembering the volume settings in that Youtube video, Local Shared Objects have been shown to be a valuable feature.
5. If you're worried about this, just wait until you guys see the Storage APIs in HTML5. You're going to freak.
Javascript + Nintendo DSi = DSiCade
I flashed my cookies once and did a weekend in the slammer.
See my journal for slashdot ID's by year. Mine created in 2005. http://slashdot.org/journal/289875/slashdot-ids-by-year
I don't allow any site to store any information on my machine, except when it is beneficial to me. That means, Slashdot can store cookies (session only), RevLeft can store cookies for ever, and various email places can store session only cookies.
However, every other site is blocked by default (Firefox plugin called CookieSafe). With Flash, yes I'm using Macromedia's shit plugin, but even then the default (and I'm not going to change it) is to not allow any site to save any information.
Of course, I also use NoScript and AdBlock... Yada yada.
I'm on the web for my benefit, not for the benefit of advertisers and other scum.
I've also heard about a trick to delete the folder where the Macromedia plugin stores the stuff and replace it with a read only blank file of the same name. Look into that if you don't trust Adobe as far as you can kick them...
I wank in the shower.
"Here's the user-unfriendly GUI for deleting them, one at a time, each one requiring confirmation."
Except there's a button to delete them all at once.
Seriously, get flashblock from the Firefox addons site. You need it. Badly. The number of sites with the equivalent of the pixel.gif tracking or the Google Analytics type JavaScript tracking, but as a small Flash plugin are growing astronomically, and Adobe has no reason to favor your privacy over their customer's demands. These little apps aren't there to serve your needs or improve you're browsing experience, and they just should never run. If you want to run a Flash app, that's fine: click on it to run it.
I use Flashblock and I've been watching Hulu and YouTube and enjoying all sorts of sites that use Flash. I'm also instantly aware of any site that's too lazy to present a standard Web page when I see a giant "click to run" button over the whole page, and I find another site. This is part of the process, and is an important way that neophyte Web developers learn that they can't just throw up Flash and not worry about Web standards.
My specific comment to this news article and your response is that third party objects always reduce security as they increase features and that is a constant and yes that is not new.
A slight side-note...
You must be new here. Welcome to Slashdot.org where you can get news of many varieties. Some is stale dated, some is duplicated but it's all kinda interesting to talk about and that is why most of us like it here.
Because even if the news is old, the discussion at Slashdot is always new! (well at least the higher rated discussions)
And a quick follow up to that post. What happens if I hit a site that requires cookies (for no apparent reason)? I leave. The most common website is lyrics websites, and considering the number of them there are, I don't care if I miss out on one more.
The same with JavaScript, there are only a few websites that I've enabled JS by default (Slashdot is one). But for all the rest, unless they have an obvious use for it (and can't provide alternative content), I leave if it's required.
Screw them. I've got better things to do with my time then fuck around with websites that can't degrade gracefully.
I wank in the shower.
This is why I don't install flash on my machines.
Way too much junk and irritating sites. A site which requires flash will be left and promptly forgotten about. If you can't provide an interface to your site without Flash, I don't care what your site has in it.
Cheers
Lost at C:>. Found at C.
On Windows, presumably the shared objects are the files stored in %USERPROFILE%\Application Data\Macromedia\Flash Player\#SharedObjects (usually c:\Documents And Settings\%USERNAME%\Application Data\... ) - can you not just delete the files directly?
I did this and it seems to work: rm -r .macromedia
ln -s /dev/null ~/.macromedia
YMMV.
I have left slashdot and am now on Soylent News. FUCK YOU DICE.
Or... a simple batchfile for neutering the little bastards completely. ... assuming they haven't changed anything.
Go to This site
1.) Go to Website Storage settings -> Delete all sites
2.) Go to Global Storage settings -> allow 0 kb of storage
3.) ????? 4.) Profit! (and/or continue going to porn sites...)
Yes, I do that on Linux regularly.
Just add this to your crontab:
0 * * * * rm -rf ~/.macromedia ~/.adobe
(If you actually use their other products, you might want to be more specific, like ~/.adobe/Flash_Player)
Use my userscript to add story images to Slashdot. There's no going back.
I can understand if there's a bug that lets one site read or write another site's cookies. But how are properly functioning cookies any threat to privacy? They are indeed a threat to anonymity, only because they let a site ID a browser (or a Flash player or some other client) as "the same as that other time". But what private info other than that you are the same person (or maybe not, on a shared machine) is threatened? The remote site could just store on its server any info about your transactions. It could require that you login to verify that you're that same returning visitor. And even without cookies, a remote site could send any info it got from your transactions over to any other site without notifying you. Cookies have nothing to do with it.
Of course, any info stored on my machine should have a usable UI to manage it. But an inconvenient one isn't really a "privacy threat". After all, what is the threat? What goes wrong when it's abused?
--
make install -not war
Mod parent "OldManOnPorchWithShotgun"
Can you point to a source, please?
Because the front page of FlashBlocks site says something different:
Flashblock is an extension for the Mozilla, Firefox, and Netscape browsers that takes a pessimistic approach to dealing with Macromedia Flash content on a webpage and blocks ALL Flash content from loading. It then leaves placeholders on the webpage that allow you to click to download and then view the Flash content.
(Emphasis taken from source)
What?
"... all your cookies are belong to us..."
- the Cookie Monster.
Shouldn't that be Adobe Flash now?
... and then they built the supercollider.
So, tell me... How is it that a flash application available on-line (from adobe) is able to delete and assign space to those very elements? You are telling me that it is not, in turn, able to access those very items? And, if it can access those items, is this not a far worse security issue than browser cookies?
Just wondering.
Now, add to this (the configuration panel for flash storage being available on-line, accessible without the need of a password) to the actual (closed source) implementation of flash -- aren't alarm bells going off in your head?
Just another "Cubible(sic) Joe" 2 17 3061
ffs, there are plenty of irritating html sites as well...
I'm over this repetitive anti-flash argument. (Honesty disclaimer, yes, I develop quite a bit in flash. No, not banner ads, and no, not fully-flash online banking applications either.)
flash != junk
people making junk with flash == junk
(and you can replace 'flash' with plenty of other technologies as well - regexp not supplied.)
If you don't install flash then that's fine and it's your choice, but you can't blame adobe or flash for webcrap. Blame the mofo's making the junk. Same applies for html+javascript badness - you don't blame the w3c and javascript interpreter writers... (or maybe you do, I don't know.)
If you don't want advertising, adblock/whatever the sites hosting it. If you don't like sites that are full of rubbish made in flash, simply don't visit them again etc. If they're pushing what you don't want then why are you there? If they're pushing what you want in a format you don't like then consider letting them know.
Sites that want to deliver rich media experiences, (increasingly) cross-platform interactive experiences, games, video, etc. will continue to use software like flash to deliver their products, messages and services until something better comes along. I don't know much about silverlight, but most articles I've read on slashdot don't exactly endorse it. Anyway, something better will come along and developers will be all over it, web standards or not unfortunately.
And yes, sure, you can jump up and down and complain that your favourite cross-browser javascript api+libraries can deliver what flash can, but currently that's not true in some or even a lot of situations, depending on what you're building. I accept that this statement is pretty broad, everything looks like a hammer or a nail or whatever analogy you prefer...
So, fitness for purpose. I'm sure most of us wish that more developers (ourselves included) used technologies appropriately, but not everyone has the same skills, audience, timeframes, etc. and certainly never the same morals.
Webcrap will continue to be made, no doubt - but I guess my point is that crap is technology agnostic.
With Flashblock loaded and active, watching hidden the Macromedia directories, visiting a page with Flash objects created objects in the Macromedia\Flash Player\#SharedObjects and Macromedia\Flash Player\macromedia.com\support\sys directories, without running any of the visible Flash objects.
That would indicate to me that some part of Flash is being activated, despite the presence of Flashblock...
Who should I contact?
Is this a serious problem?
I read about this sometime ago, so keep in mind that it may no longer be correct. As I understand it, Flashblock works by analyzing the DOM as it's loaded and anytime it sees Flash content it removes it and inserts its own Flashblock placeholder. What this means is that it is possible for Flash to execute before it is removed, however given the delay before the SWF in question is downloaded it's very unlikely that it would begin executing before Flashblock is able to remove it.
You and the GP AC are correct. Try running FlashBlock on a very slow PC and you'll see the first frame of the Flash application display... but this was witnessed by me over 6 months ago, I have not been back on my old, slow PC in a while.
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