Malvertising

Malvertising↗ is the use of online advertising to distribute malware↗, often by injecting malicious code into legitimate ad networks that display on otherwise trustworthy, high-traffic websites. A user can become infected simply by loading a page with a malicious ad, sometimes without even clicking on it.

Because the surrounding website is often reputable and unaware of the problem, malvertising can spread malware at massive scale before it's caught and removed. Ad blockers, keeping browsers and plugins updated, and avoiding sites that host excessive advertising all reduce exposure to malvertising.