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Flash Player can store information on your computer much like your browser stores cookies. We'll look at the risk, and how to manage the settings.

I had a problem installing a program on my computer. After 20 minutes with tech support we found the problem was my Macromedia Flashplayer settings. Sometime in the past when Flashplayer asked if it could store stuff on my computer I had changed the memory setting to NONE. Changing the setting to allow Flashplayer to save stuff on my computer solved the problem.

What are the benefits/dangers of allowing Flashplayer to store stuff on my computer. What are your thoughts on these settings, and what the best/safest setting should be?

Macromedia Flash (long since purchased by Adobe) has exploded in the web as the platform-independent dynamic content player of choice. If you've ever watched a video on YouTube (and who hasn't?), you used the Flash Player to do it.

What many people don't realize is that, yes, Flash can store information in on your computer for the site you're visiting.

You've heard of "cookies", as used by your internet web browser? There's a new term in town: flash cookies.

The problem with information stored by flash player is not only do most people not realize that the information is stored at all, but it's also not obvious how to clear it, or prevent it.

"Clearing your browser's cache, cookies or other information will not clear the information stored by Flash."

While the information stored by Flash Player is very much like browser cookies - the information is made available to the site that put it there in the first place - it's not related to your browser in any way. Clearing your browser's cache, cookies or other information will not clear the information stored by Flash.

You can control Flash Player's behaviour with respect to the data it stored by visiting the Flash Settings Manager, which is not surprisingly a Flash application on the Macromedia/Adobe web site. There you can visit the "Global Storage Settings Panel" to control how Flash should deal with local storage:

Adobe Flash Player Global Storage Settings Panel

Here you can control how much space is used, or whether applications are even allowed to store information on your computer at all. (It's worth visiting the other tabs in the Setting Manager. They'll let you control content on a site by site basis, as well as other privacy and security settings.)

So, what's the risk?

In my opinion the risk is very similar to browser cookies - in other words, not much.

There's little to no security risk, as stored information is just that, stored information and nothing more. Barring unpatched vulnerabilities in Flash or your system, this stored data cannot be used to spread malware or infect your system.

The risk, to the extent that it exists, is one of privacy. Much like browser cookies, Flash information can be used to remember the sites you've visited (if they, or their advertising networks use Flash), and perhaps even what you've done while on that site. (Typically, again like browser cookies, the stored Flash information is really just used to remember your settings and choices for you.)

I don't see this as a huge issue. As I've said repeatedly, you, as an individual, just aren't that interesting. No one cares what you do. What they care about, perhaps, is finding out that 1,000 people like this site, and 2,000 like this other site, and other types of "aggregate" information. Exactly who those 1,000 or 2,000 people are is lost when the information is collected.

But of course not everyone feels the same way.

The other side of the issue is that, as you've seen, some applications simply require the ability to store information and won't work if they can't. That's simply a decision you'll need to make as you visit sites that use Flash.

Article C3790 - June 26, 2009 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

June 26, 2009 2:16 PM

I'm using the BetterPrivacy add-on for FF which clears Flash cookies when I close the browser. I have it set to prompt me, but it will also do so automatically.

June 30, 2009 9:44 AM

Many utility cleaners will have a setting to clear flash cookies. I like Crap Cleaner or CCleaner for short. Another is free internet window washer 2.5 Bye

June 30, 2009 1:40 PM

THANK you for the Flash manager link! Hugely useful.

I understand that all things don't work the same in all situations....but I tried CCleaner once. Result was a complete reformat/reload of my PC!

ANY advertised registry 'cleaner'or 'fixer'is something to be extremely wary of, imo.

July 13, 2009 11:53 PM

where store web cam recorded .FLV FILE BY adobe flash player IN WEB APPLICATION IN ASP.NET WITH C#

July 20, 2009 12:15 AM

Admitted: I'd never heard of flash cookies until reading this.

I have used the great program CCleaner for many years. (I run it numerous times a day!) Yet I don't see anything about or settings for cleaning flash cookies. Are they automatically cleaned with other browser cookies? (CCleaner v. 2.21.940)

October 2, 2011 3:24 AM

i m using adobe flash player
i stored an flash game i played it and completed it
where the files of it stored

October 28, 2011 11:58 AM

When I stopped allowing Flash to store info on my computer my 6 year old computer really got a lot faster. Just a coincidence? Probably not!

June 27, 2012 1:41 PM

cCleaner works for flash cookies and stored file removal. I us it on all my windows machines but I will warn people to only use the functions that you understand.
If the check box is in the advanced section, know what it is before you check it.
Do not check your anti virus as it will remove your updates.
Check, all of your browser boxes, all Flash player boxes, Windows Explorer, temporary files, clipboard, recycling bin, memory dumps, log files, and all multimedia.
I recommend that you only use the “Cleaner” option in the program/ the one that shows a brush.
This should keep your computer clean of hundreds of files that would otherwise be stored in your computer and in some cases, use quite a bit of HD space.
cCleaner works for me but there are others that do the same thing and work well.
In Linux, I use Bleachbit.

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