Local Shared Object

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A Local Shared Object (LSO) is a collection of cookie-like data stored as a file on a user's PC. LSOs are used by all versions of Adobe Flash Player and Version 6 and above of Macromedia's now-obsolete Flash MX Player.[1]


[edit] Privacy concerns

Flash Players use a sandbox security model. With the default settings, Adobe Flash Player does not seek the user's permission to store LSO files on the hard disk. LSO's contain cookie-like data stored by individual web sites or domains. Any kind of text data can be stored, some of which may be cause for privacy concerns. Indeed, as with cookies, online banks, merchants or advertisers may use LSOs for tracking purposes.[2]

However, in order to respect people's privacy and for security purposes, the current version of Flash does not allow LSOs to be shared across domains. For example, an LSO from "www.example.com" cannot read an LSO created by the domain "www.example2.com".[3]

[edit] User control

Local Shared Objects are not temporary files. Users can opt-out of them on a per-site basis by right-clicking and selecting 'Settings', or can opt-out globally by using the Global Storage Settings panel[4] of the online Settings Manager at Adobe's website.

Adobe's Website Storage Settings panel was created to let users view and delete LSOs on a per-domain basis. It is also possible to completely disallow LSOs from a specific domain by setting the storage space to "0 KB"[5] Add-on extensions have also been created for the Firefox Web browser, called Objection[6] and Better Privacy that allow the user to view and delete LSOs.[7]

[edit] File locations

The default storage location for LSO files is operating system-dependent. LSO files are typically stored with a ".SOL" extension, within each User's directory. Note that for self-executing flash applications run on the local machine will show up as being run on a website, in the folder localhost.

  • Windows XP and Vista:
    • For Web sites: %APPDATA%\Macromedia\Flash Player\#SharedObjects\<random code>\<domain>\<path>\<object name>.sol
    • For AIR Applications, %APPDATA%\<AIR Application Reverse Domain Name>\Local Store\#SharedObjects\<flash filename>.swf\<object name>.sol
  • Mac OS X:
    • For Web sites, ~/Library/Preferences/Macromedia/Flash Player/#SharedObjects/<random code>/<domain>/<path from webserver>/<object name>.sol
    • For AIR Applications, ~/Library/Preferences/<AIR Application Name>/Local Store/#SharedObjects/<flash filename>.swf/<object name>.sol
  • Linux/Unix:
    • ~/.macromedia/Flash_Player/#SharedObjects/<domain>/<path>/<flash filename>.swf/<object name>.sol

[edit] Programming

The Flash Player allows Web content to read and write LSO data to the computer's local drive on a per-domain basis;[8] such data may preserve session state and record user data and behavior.[9]

A Flash application may store up to 100kb of data to user's hard drive (browser cookies have a limit of just 4kb).[8] The defined storage sizes are 0kb, 10kb, 100kb, 1Mb, 10Mb, and Unlimited.[10] If the current limit is exceeded, the user is shown a dialog requesting storage space of the next size. The user may override the amount manually by clicking the Flash application with right mouse button and selecting Settings; however, this applies only to the domain of the Flash movie. If the selected setting is smaller than the current data size, the data is deleted.

Global LSO settings may be amended by the user, by browsing Adobe's Web page that invokes Adobe's "Global Settings Manager" control panel.[10][11]

[edit] Editors and toolkits

Software Website Developer First public release Latest stable version Cost (USD) Open source License Programming language
SolVE SolVE Darron Schall 2004-09 0.2 (2004-10-15) Free Yes CPL Java
.sol Editor .sol Editor Alexis Isaac 2005-02 (2005-02-21) Free Yes MPL ActionScript, Delphi/Kylix
Dojo Toolkit Dojo Toolkit Dojo Foundation 2004 1.0.2 (2007-12-19) Free Yes BSD, AFL JavaScript
MAXA Cookie Manager MAXA Cookie Manager Maxa Research  ? 3.2 (2009-02-02) 35 No proprietary  ?
PyAMF PyAMF Nick Joyce 2007-10-07 0.4 (2009-01-18) Free Yes MIT Python
SOLReader SOLReader Alessandro Crugnola  ?  ? Free No  ? C#, PHP [12]
s2x s2x Aral Balkan  ?  ? Free Yes  ? Python [13]
.minerva coursevector.com Gabriel Mariani  ? 2.0 (2008-10-06) Free Yes  ? AIR

[edit] Operating system support

Software Windows Mac OS X Linux BSD Unix
SolVE Yes Yes No No No
.sol Editor Yes No Yes[14] Yes[14] Yes[14]
Dojo Toolkit Yes Yes Yes Yes Yes
MAXA Cookie Manager Yes No No No No
PyAMF Yes Yes Yes Yes Yes

[edit] References

  1. ^ "What are local shared objects?". Adobe. http://www.adobe.com/products/flashplayer/articles/lso/. Retrieved on 2007-12-05. 
  2. ^ "Flash Player Worries Privacy Advocates". InformationWeek. http://www.informationweek.com/news/showArticle.jhtml?articleID=160901743. Retrieved on 2007-12-05. 
  3. ^ "Flash Player : What Is a Local Shared Object?". Adobe. http://www.adobe.com/products/flashplayer/articles/lso/. Retrieved on 2009-03-27. 
  4. ^ "Adobe - Flash Player : Settings Manager - Global Storage Settings Panel". Macromedia.com. http://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager03.html. Retrieved on 2009-03-27. 
  5. ^ "Adobe - Flash Player : Settings Manager - Website Storage Settings panel". Macromedia.com. http://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager07.html. Retrieved on 2009-03-27. 
  6. ^ "Objection web site". http://objection.mozdev.org/. Retrieved on 2007-12-05. 
  7. ^ BetterPrivacy 1.24. "BetterPrivacy :: Firefox Add-ons". Addons.mozilla.org. https://addons.mozilla.org/en-US/firefox/addon/6623. Retrieved on 2009-03-27. 
  8. ^ a b "Macromedia Flash MX Security". Adobe. 2002-03-01. http://download.macromedia.com/pub/flash/whitepapers/security.pdf. Retrieved on 2007-12-05. 
  9. ^ "Local Shared Objects -Flash Cookies". Electronic Privacy Information Center. 2005-07-21. http://www.epic.org/privacy/cookies/flash.html. Retrieved on 2007-12-05. 
  10. ^ a b "Global settings manager". Adobe. http://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager.html. Retrieved on 2007-12-05. 
  11. ^ "TechNote: How to manage and delete local shared objects?". Adobe. http://www.adobe.com/go/52697ee8. Retrieved on 2007-12-05. 
  12. ^ "PHP example with source code". Alessandro Crugnola. http://www.sephiroth.it/assets/utils/SolReader.phps. Retrieved on 2007-12-18. 
  13. ^ "Web demo written in Python". Aral Balkan. http://icube.freezope.org/temp/util/s2x. Retrieved on 2007-12-18. 
  14. ^ a b c Originally written for Microsoft Windows, but will run on Unix-like systems using Wine

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