Adblock Plus offers new Facebook advert filter and strikes on free content sites

[Len]

The game of advert cat-and-mouse continues.

Adblock Plus has struck online advertising another blow by offering a new filter for users who want to block Facebook ads.

Ad-blocking apps, plugins, and software are used to strip the majority of advertising out of website pages, social media networks, and other online services.

While they can prevent malvertising -- fraudulent and malicious ads -- from potentially placing users at risk, they can have a massive knock-on effect for companies that rely on advert-generated revenue to stay afloat and keep offering free content online.

There's no easy option -- although The Pirate Bay has recently turned to visitor CPU cryptocurrency mining as an alternative to ads -- beyond negotiation between vendor and ad-block provider, or making ads more seamless to prevent users from turning to such software in the first place.

Some of the time, a game of cat-and-mouse comes into play, with adblockers on a campaign to block adverts, and vendors changing tactic to stop it occurring.

Adblock Plus and Facebook have been battling for some time now. Every time an ad-blocker introduces ways to remove ads, Facebook plays whack-a-mole and brings ads back to the forefront once more.

This week, Adblock Plus swung again, by announcing the addition of a new filter capable of blocking out likely adverts on the social networking site.

The new filter depends on a new "has" filter -- currently available only on Chrome and Opera -- to "read" Facebook posts and pick out the telltale signs of an advert. If elements which appear to be advertising appear, then the post is blocked.

Adblock Plus says that web elements at the top or parent level are often marked with advertising signals. However, Facebook obfuscated these signals by moving ad signatures below the parent level, rendering ad blockers ineffective.

The new filter allows the blocker to snoop under the top of the sub-elements below it, resulting in potentially some success with removing adverts.

"We're outfoxing Facebook's latest attempt to hide the ads on their site so ad blockers can't block them," Adblock says. "We're reasonably sure that Facebook's IT army will eventually outfox our outfoxing. Just like death and paying taxes, Facebook will continue the cat-and-mouse game, ushering in a fix that will stop ad blockers.

"The difference this time around, versus the back and forth our community shared with Facebook last fall, is that due to our community's hard work, we'll be able to respond more quickly to Facebook's next anti-block volley," the company added.