Firefox 18.104.22.168 closes ad blocking loopholes · 2007-04-19 00:57 by Wladimir Palant
Adblock Plus has just got a little more useful. Yesterday two patches of mine landed on the Mozilla 1.8 branch which will be used for Firefox 22.214.171.124. What are they good for? They close loopholes that advertisers could use (and some already do use) to initiate requests to their servers without Adblock Plus interfering. One loophole is XMLHttpRequest commonly used by AJAX application, the other are requests created by plugins like Flash — neither of the two went through content policies (meaning Adblock Plus as well) before. I just downloaded the current Mozilla 1.8 nightly and verified that this has changed.
Let’s take the example that brought up this topic originally: Yahoo Maps. The whole user interface including the ads is implemented as one single Flash object. This means that in Firefox 126.96.36.199 you have “all or nothing” choice — either you block the Flash object which effectively locks you out of Yahoo maps or you don’t block anything and have to accept the ads. But if you open the list of blockable items (Ctrl+Shift+B) in Firefox 188.8.131.52 you will see a whole lot more there, lots of addresses with type “other”. That is data requested by the Flash object, some of it displayed and some processed internally. In particular you will see some addresses starting with “http://xml1.maps.yahoo.com/flashAds.xml”, that’s the data used to display ads. Add the filter “|http://xml1.maps.yahoo.com/flashAds.xml?*” to your list and the ads disappear (I hope to see this filter in EasyList soon).
Note that this might not work correctly in Adblock Plus 0.7.2.4, you should upgrade to Adblock Plus 0.7.5 (hopefully released tomorrow, release candidate is here). And of course it will not work in Adblock which ignores type “other”. Finally, Yahoo Maps uses browser sniffing that causes it to behave strangely in Firefox nightlies. To “fix” go to about:config, find the preference general.useragent.extra.firefox and replace “BonEcho” by “Firefox”.
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