Here are just three of the worrisome changes:
AdBlock 2.6.11 (2013-10-25): The AdBlock feature which sends a unique user ID to the AdBlock server every day (you knew about this one, didn’t you?) has been extended. The server can now decide that the user should see a survey — this one is being opened in a new tab, immediately, no matter what the user is doing right now.
AdBlock 2.6.14 (2013-11-09): AdBlock won’t just send a unique user ID to its server now, it will also transmit user’s setting determining whether Google Search ads are allowed. The changelog message for this release: “Settings measurement.”
AdBlock 2.6.20 (2014-02-11): AdBlock will now send a request to goldenticket.disconnect.me each time it starts up — but not in the first two days after installation. It took a while until people noticed, apparently AdBlock partnered with Disconnect.me and advertises their services to selected users. The Disconnect functionality has been actually bundled with AdBlock and ads in their search were whitelisted. Another interesting addition: the unique user ID mentioned above will be sent to getadblock.com every time an AdBlock user visits that website. Or if an AdBlock user visits getadblock.com.malicious.com. Or any other website that has getadblock.com somewhere in the host name. If I were owning a website relying on ad revenue, I would have inserted a hidden frame into every page and used that bug to track AdBlock users — maybe some websites already had the same idea? And how does the changelog describe these changes? “Beta test for survey” – yes, sure.
If you don’t update how can it send data that it did not do in previous versions? It cannot, so therefore use the older version.