Visit any website these days and it’s very likely that you will be viewing ads as well. Sometimes these ads can be tempting, with many offering sales, promotions, or freebies to attract more clicks. Ads on certain websites can even be targeted specifically to you based on past browsing history, making you even more likely to click!
Remember this: just because you are on a reputable, well-known website, it does not mean that the ads on the website are safe to click as well.
How adspace can become infected: Advertisers do not sell their ads to websites one at a time. Websites that want to make money sell their advertising space to an ad network. Advertisers sign contracts with that ad network which then displays the ads on the participating websites. The ad network sits in the middle between the advertisers and the websites and manages the traffic and the payments.
Cybercriminals can take advantage of this system by fooling the ad networks into thinking they are a legit advertiser, but the ads which are displayed on major websites can be poisoned. If you browse to a page with a poisoned ad on it, that is enough to run the risk your PC will be encrypted with ransomware, which can hold your computer or your entire network hostage until you pay the cybercriminal a ransom.
Tips to prevent the effect of harmful ads:
- Disable Adobe Flash on your computer - or at least set the Adobe Flash plug-in to "click-to-play" mode - which can block the automatic infections.
- Keep up-to-date with all the security patches and install them as soon as they come out.
- Download and install a reputable ad blocker plug-in for your browser. These prevent the ads from being displayed in your browser to start with. These ad blockers are getting very popular with hundreds of millions of people using them.
Stop Look Think - Don't be fooled
The KnowBe4 Security Team