Facebook has appeared to have entered a tech war with ad blocking company, Ad Block Plus. The social network recently attempted to bypass ad blockers on its site using what they called “ad preferences”. The idea was to allow users to opt-out of adverts about a certain subject, meaning the blocking software would not be necessary. However, just days' after the changes were put in place, Adblock Plus developed a system that tricked Facebook into thinking the ads were normal posts. Andrew Bosworth, Facebook's advertising chief, wrote on Twitter that his team “plan to address the issue." Adblock Plus meanwhile have said that “for this round of the cat-and-mouse contest, looks like the mouse won." The blocking company have caused controversy in the past due its business plan, which allows ads through if the advertiser pays it a percentage of the revenue.