Tuesday 16 August 2016

Adblocking is asymmetric warfare and publishers can't win

For those of us who like to keep an eye on developments in web advertising blocking (adblocking), there was a flurry of excitement last week as Facebook announced that it had designed and released a way to defeat the blockers. Adverts inserted into Facebook's news feeds have been made harder for an adblocker to tell apart from regular posts by your friends. If the blocker can't spot the ad, it can't remove it.

This has been coming. Various companies have been trialling experiments ranging from asking people nicely not to block ads (The Guardian) to attempting to completely prevent access to a site for those running adblockers (CityAM).

The response to Facebook from Adblock Plus has also been coming. Its Open Source community defeated Facebook's new tech in less than 48 hours.

On Thursday, Facebook announced another change.

And Adblock Plus killed that one the following day.


I've been plugging away on Twitter for a while with the opinion that big publishers can't win an arms race with adblockers. In this post, I'd like to explain why.



Adblocking is asymmetric warfare. On one side, you have large companies - publishers and ad-tech suppliers - who deliver adverts. On the other you have a growing population of people, estimated at 12m (pdf) in the UK, who want to block ads and a series of smaller software projects which allow them to do that.

Effective asymmetric or guerrilla warfare is all about harassment, persistence and the ability to adapt quickly against a large and powerful, but much slower opponent. Guerrilla combatants don't win a definitive victory, but eventually their opponent is forced to give up and make a deal, because they're burning through resources and not achieving very much.

In order to deploy its new solution, Facebook had to develop the code, test it and then deploy it onto a system serving 1.2 billion users, without breaking anything. Adblock Plus took less than 48 hours to nullify that solution - twice - and did so for free.

The blockers haven't even really had to get sophisticated yet to remain effective. All most adblockers do, is check against a list of server addresses that deliver adverts and web page elements which contain them and remove those before the page is shown to a user.

For a newspaper or Facebook to show an ad, a bit of code is inserted in the web page that effectively says:

[start advert]
Call ad-server and request an ad!
[end advert]

Facebook made that code more difficult to spot, but apparently not difficult enough.

Let's say Facebook got really clever with hiding their ads and mixing them up so the code for their containers and servers looked exactly the same as your friends' posts. What could blockers do in response?

1. Compare the posts in your news feed to your Facebook friends list and zap anything that doesn't match. It requires more coding than just killing advertising flags on a web page, but it's not really difficult... There are already plugins that have this functionality.

2. Use the legal requirement that adverts are clearly labelled as being adverts, as a way for blockers to find and remove them. You've got to write "ad" in the corner of an advert to obey the law. This stuff really isn't that hard.

3. Start training machine learning models to use the content of adverts to identify and remove them. A Gmail spam filter for the whole internet. Are you sure you want to start this fight?

None of those even touch on the idea of weaponised adblock, which it's not unusual to see suggested on tech forums. Currently, adblockers are passive; they prevent an advert from loading. But they don't have to be. Adblockers could deliberately load and click on ads in the background, thousands and thousands of times - without showing them to the user - to screw up the web's revenue model. I'm absolutely not saying they should, but they could, and the idea isn't new.

Are you really sure you want to start this fight?

This is why the advertising industry must acknowledge - whatever its position on the morality of adblocking - that it can't win an arms race with the blockers. Adblocking counter-measures are slow and expensive to roll out and industry wide, will need the cooperation of a huge number of participants.



Blockers can rely on a passionate community of skilled programmers who iterate and deploy new solutions quickly. The blockers don't have to win every time or force a dramatic surrender, they just have to make life difficult and expensive for the ad industry until it eventually gives up.

Advertisers, agencies and publishers must acknowledge three key facts:

1. Adblock penetration is growing rapidly and this is a problem

2. Publishers cannot win an arms race with adblockers

3. A large and growing section section of the population is on the side of the adblockers and so is the law.


It is imperative that the advertising industry identifies the reasons for the rapid growth of adblocking, in order to work towards an alternative to the current situation, where over 20% of people in the UK consume all non-paywalled internet content entirely for free.

This alternative is likely to encompass a model where adverts are no longer a vector for malware, are significantly less irritating to users and provide for much better privacy.

(no, this chart doesn't follow my data vis best practice)

As I've written previously, our new world may well be a much nicer place for large publishers delivering quality journalism. Their audiences won't be trackable onto thousands of tiny websites, so large publishers will be in a much better position to charge a premium for advertising space.

For better or worse, this new world is coming. If you target younger, tech savvy audiences, it is already here. It can't be fought so we must work out how to be effective within it.