Local Shared Object - Storage

Storage

Local shared objects contain data stored by individual websites. With the default settings, the Flash Player does not seek the user's permission to store local shared objects on the hard disk. By default, a SWF application running in Flash Player from version 9 to 11 (as of Sept 1, 2011) may store up to 100 kB of data to user's hard drive. If the application attempts to store more data than the allotted default, the user is shown a dialog to allow or deny the request for more storage space.

Adobe Flash Player does not allow 3rd-party local shared objects to be shared across domains. For example, a local shared object from "www.example.com" cannot be read by the domain "www.example2.com". However, the first party website can always pass data to a third party via some settings found in the dedicated XML file and passing the data in the request to the third party. Also, third party LSOs are allowed to store data by default. By default LSO data is shared across browsers on the same machine. As an example:

• A visitor accesses a site using their Firefox browser, then views a page displaying a specific product, then closes the Firefox browser, the information about that product can be stored in the LSO.
• If that same visitor, using the same machine now opens an Internet Explorer browser and visits any page from the site viewed in Firefox, the site can read the LSO value(s) in the Internet Explorer browser, and display dynamic content or otherwise target the visitor.

This is unique from cookies which have directory isolated storage paths for saved cookies while LSOs use a common directory path for all browsers on a single machine.