Better Privacy Firefox add-on v1.65
Released 29-July 2011 BetterPrivacy is a Firefox add-on that is able to delete a special kind of cookies: Local Shared Objects in short LSO's (usually known as Flash-cookies) are placed on your computer by a Flash plug-in.
Why are LSO's harmful?
* they are never expiring - staying on your computer for an unlimited time
* by default they offer a storage of 100 KB (compare: Usual cookies 4 KB)
* browsers are not fully aware of LSOs, LSO's often cannot be displayed or managed by browsers
* via Flash they can access and store highly specific personal and technical information (system, user name, ...)
* ability to send the stored information to the appropriate server, without user's permission
* Flash applications do not need to be visible to the user
* there is no easy way to tell which LSO sites are tracking you
* shared folders allow cross-browser tracking, all browsers use the same LSO folder
* the company doesn't provide a user-friendly way to manage LSO's, in fact it's incredible cumbersome
* many domains and tracking companies make extensive use of LSOs
* LSOs are used to re-create data of deleted traditional cookies
Since Flash is a seperate application, running on your system (not under the hood of Firefox) , there is technically no way to prevent it from storing those LSO's on your disk. However they can be deleted at any time but unfortunately most browsers are unable to display or manage LSO's. BetterPrivacy can help here and offers capabilities to list and manage stored LSO's, up to full automatic cleaning, while allowing to define LSO-removal exclusion rules.
Better Privacy:
http://netticat.ath.cx/BetterPrivacy/BetterPrivacy.htm