CrunchBang Linux

fhsm

#! Junkie

From: New Hampshire, USA

Registered: 2009-01-05

Posts: 443

Simple Flash local shared object protection

I suspect everyone is up on the privacy ramifications of HTTP cookies.  I personally have FF set to not accept 3rd party cookies and dump all but a small white list of first party cookies when FF closes.  That said I only recently learned about Flash cookies.  Long story short, Flash stores persistent storage objects that serve a cookie function.  You can read more here or here. 

After reading up on flash cookie privacy I found an addon to help manage flash cookies in firefox called BetterPrivacy.  It has been working well for me.  The problem is I use other browsers (Midori, Opera, Kazehakase) in addition to FF.  So I needed a plan B: a cron job that dumps the the flash junk from the day in the middle of the night. 

1) Find the target Look in ~/.macromedia/Flash_Player/#SharedObjects, I have two system and they have different setups in this directory.  Setup one, directories with the names of domains I visit (ex: /youtube.com).  If your like this go on to step two.  Setup two, a lone directory with a random name like "ZKAEK53N" open that directory and confirm it holds directories with the domain names of sites you visit.  Make a note of that directory name, I'll call it <YOUR_DIR> moving froward.

2) Write the cronjob Make a new text file ~/cron_cookies.txt.  If you had setup one put the following in ~/cron_cookies.txt:

 15 4  * * * rm -rf ~/.macromedia/Flash_Player/#SharedObjects/* && rm -rf ~/.macromedia/Flash_Player/macromedia.com/support/flashplayer/sys/* 

If you had setup two put the following in ~/cron_cookies.txt, replacing <YOUR_DIR> with the name of the single directory noted in step 1:

 15 4  * * * rm -rf ~/.macromedia/Flash_Player/#SharedObjects/<YOUR_DIR>/* && rm -rf ~/.macromedia/Flash_Player/macromedia.com/support/flashplayer/sys/* 

If you don't know what this means you can get the flavor here.  The key think to know is that the 4 is 4AM and the 15 is 15 mins after the hour.  You may want to change those times.

3) Apply the cronjob Open a terminal apply this job by running:

crontab ~/cron_cookies.txt

That's it, your flash junk should get dumped at 4:15 each morning.

Few notes
A) I didn't have any cronjobs so this isn't a problem but that approach will overwrite your crontab if you've already got something in there.  If you need to append use crontab -e and type the job in there.
B) The second directory ~/.macromedia/Flash_Player/macromedia.com/support/flashplayer/sys may or may not be necessary.  I think that directory may just caching players but I haven't been able to find a clear source on this and haven't had any problems dumping it.

Last edited by fhsm (2009-04-18 02:56:03)

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FHSM: avoid vowels and exotic consonants and you'll get your handle every time.  identi.ca