Blocking Adobe Flash® for Fun and Profit

Blocking Flash elements on a web page not only has performance advantages (page load time, CPU usage, power-battery-heat-fan, etc.), but it is also one of several basic necessities for web privacy.

FlashBlock is an extension for Firefox that replaces each flash element on a page with a click-to-load button. It gives you full control to only load the elements you really want, and has a whitelist to bypass blocking on specific sites.

ClickToFlash is a freeware (donations accepted) WebKit plug-in alternative for Safari on Mac OS X. Is has similar one-click Flash loading and a whitelist, but also has a preference that lets you force YouTube to load h.264 video instead of Flash, with no extra click needed. Be sure to customize the settings, particularly by unclicking the "Automatically load invisible Flash views" box, which will then also block small (< 8x8 pixel) Flash bugs.

FlashBlock and ClickToFlash addresses the performance issues, and to some small extent privacy by limiting the number of Flash elements that can access your hard drive, but more controls are needed to address even basic privacy concerns.

Adobe Flash is nearly ubiquitous on personal computers and very few people are aware of, let alone know how to effectively manage, the extensive and intrusive Local Stored Objects (AKA LSOs, Flash cookies, or Persistent Identification Elements - PIE) it reads and writes on your hard drive. Even Adobe's own (obscure) web-based management tool is incomplete and not effective for all scenarios. Find the Macromedia folder on your system... you may be quite surprised what, and how much, you find there. These files can store large amounts of personalized data, and they can be accessed across browsers (and potentially by other applications too). In other words, a Flash cookie set by a web site you browsed to in Safari can be read by a web site you later browse to in Firefox.

There are a variety of procedures and tools for managing Flash "cookies", but the BetterPrivacy extension for Firefox is one of the easiest and most complete.

BetterPrivacy is a simple tool to manage both Flash cookies and DOM Storage (another kind of obscure but persistent file read and written by web sites). It let's you choose to delete Flash cookies and their directories on browser start-up, exit, and even on a timed interval (as long as the browser is open). Again, be sure to customize the settings.

Unless (or until) web sites better disclose and provide opt-outs and major browsers build in controls for effectively managing these persistent files, I'll continue to use the nuclear option: keeping these and all other kinds of tracking data purged on a regular basis.