Adblockers are the new AntiVirus

Back in November I wrote a blog entry about good browsing habits being insufficient to protect you from malware.  Here is an update.  This week I had three brushes with malware, all three having to do with news aggregators.  One came through Microsoft’s News app (previously called the MSN News app), one through the Flipboard app on Windows, and one through Yahoo’s web portal.  Both the Microsoft and Yahoo cases were attempts to get me to install a Fake AV.  The one that came through Flipboard was worse, it was a drive-by download (meaning it downloaded a file to my computer without my being prompted to allow that).  Fortunately Windows Defender Antivirus caught and quarantined the drive-by file.  And this happened despite my having tightened up my browsing habits further, by absolutely refusing to click on sponsored links in news aggregators.

First a word on sponsored links (particularly in news aggregators): JUST SAY NO to clicking on these links.  These are enticing socially engineered stories designed to pull you in to a website that is all about serving ads.  You recognize it, usually a slide show with a single slide per page and numerous (even dozens of) ads around it.  You have to click-through the slide show, with each slide resulting in numerous additional ads being displayed.  The pages are even designed so that elements display later, moving the “Next” button after a few seconds.  If you try to click next before the page has fully rendered you end up clicking on an ad instead.  These are evil pages, but the news aggregators love to include links to them because they are paid to include them.  Actually calling the sponsored links evil may be a little too harsh.  The content can be useful, or at least entertaining, but it comes at a high price.  That price is enabling malware distribution.

The real culprit here are ad-serving networks.  The ad-serving networks appear to have very poor control over their customers including malware in ads they submit for distribution.  Someone wants to pay them to display an ad 5000/times a day, no problem!  So amongst the tens or hundreds of thousands, or millions, of legitimate ads they serve up on websites each day occasionally one with malware shows up as well.  And these ad-serving networks are being used everywhere, from little mom and pop websites, to large news organization websites, to our lovable sponsored slide shows.  The more ads you see, the higher the odds a malicious ad will be displayed as well.  Some you might have to click to have a malicious result, but just like that (evil!) auto-play video others pose a threat just by being loaded.  My two brushes with Fake AV are perfect examples.  I went to a legitimate mainstream website and the scary Fake AV window displayed with no further action on my part.  Yes it would have taken overt action to actually download malware, but the whole point of Fake AV is to scare the user into performing the download.  It works all too often.

What makes the sponsored links pages so dangerous is the sheer number of ads they serve.  One slide show can display hundreds of ads.  Do a couple of slide shows a day and you are seeing many thousands of ads a week.  Under those conditions, hitting an ad distributing malware is going to happen with some regularity.

But I was hit this week without going through a sponsored link.  In fact I looked at the claimed source in the news aggregator.  In all three cases it looked like a news site I was familiar with.  In the Flipboard case I now believe it wasn’t; more on that later.  What is true is that in all three cases I was operating without ad blocking software.

Recall that browsers are really made up of webpage rendering engines that turn HTML, CSS, and JavaScript into the pages that we view and interact with.  Those engines can be invoked independent of the environment around them that we know of as “The Browser”.  It is The Browser (Edge, Chrome, Firefox, etc.) that we are using with direct browsing that provides capabilities such as invoking ad blocking extensions.  The engines themselves neither perform (general) ad blocking nor invoke extensions.  So when an app such as Microsoft News renders a web page, it does so without the ad blocking extension you’ve installed in your browser of choice.  And in something related, when you use the InPrivate (Incognito, etc.) modes of the browser the extensions are disabled.  This explains why most of the ad-carrying malware I see comes from news aggregators.  Even my Yahoo example turned out to be an InPrivate window I’d launched to log in to a website with an ID other than the one I normally use.  I’d just forgotten to kill it when I was done with that one task, and used it for general browsing.  InPrivate disables extensions because they might leak information you are trying to keep private, so I was caught without my usual protection.

That brings me to the main point.  In the beginning there was Antivirus software.  Then we discovered software, such as browser toolbars, that were tracking us and stealing information from our machines, so we created Anti-Spyware.  We created Firewalls to block undesirable network access, intrusion detection and prevention systems, various white listing solutions (app stores, SmartScreen, AppLocker, etc.) to limit the running of bad code, etc.  But there is one more tool needed for security, Ad Blocking software.

Historically Ad Blocking has been more about convenience (i.e., ads are annoying) and performance (lots more to download to display the ads).  Since ad personalization is a driver behind many intrusions on our privacy, and a channel for distributing malware, we need to treat them as malicious.  Ad blocking software prevents the ads themselves, as well as other web page elements used to track us (presumably for ad personalization) from being rendered on a web page.  Today you have to use a browser extension, but ad blocking as a default feature in web browsers is just around the corner.  Though I suspect that will still leave us with the problem that it is a browser feature, not a core engine feature, and thus not always available when pages are rendered.

I have not yet gone the route of a paid system-wide ad blocker like Adguard for Windows, but I’ll likely give it a try.  If that will work for blocking ads in applications like Microsoft News, then it would be worth paying to get the extra protection.  In the meantime on Windows I’m using the free Adguard Adblocker extensions for Edge, Chrome, and Firefox.  I use 1Blocker on iOS.  Well, at least that’s what I do as of this writing.  I’ve tried a number of them on iOS and found very little difference in the user experience.

One comment on Flipboard and the drive-by download.  I originally thought this was ad delivered, but on reflection I may be wrong.  It looked like a story on a mainstream website, but took a long time to load.  The link may actually have been to an intermediate site that first did the download then redirected to the mainstream site.    Looking like, and eventually redirecting to, a mainstream site was the social engineering to get me to click on the story link.  Trusting that Flipboard was being careful to avoid displaying misleading story links was a mistake on my part.  All news aggregators have the problem that in order to give you everything you are looking for they will include stories from the long tail as well as mainstream sites.  If their curation processes can’t identify long tail websites that are compromised or misleading (or simply not careful about content or ad networks), then they make it that much harder to stay safe on the web.  So Flipboard may have been an ad problem, or it may have been something worse.  At this point all I can say for sure is that my trust in Flipboard has been diminished.

The days of the ad-supported “free” Internet appear to be coming to an end.  Privacy concerns with the tracking needed to do extensive ad personalization has moved blocking ads and trackers from a niche to mainstream desirability.  The abuse of ad networks to distribute malware will make an blockers pretty much mandatory, and will soon result in ad blocking being built-in to browsers.  At that point, how do you make money off advertising?  The ad industry may have a window to clean up their act and prevent the industry’s collapse, but that window is small and shrinking fast.




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1 Response to Adblockers are the new AntiVirus

  1. Peter Vogel says:

    Fine article. Thanks.

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