“Malvertising” is a portmanteau of “malicious” and “advertising.” It refers to the use of online advertising to spread malware. Malvertisers exploit the online advertising ecosystem to inject malicious advertisements into legitimate web pages and ad networks. When users click on these deceptive ads or sometimes even just view the webpage hosting them, they might inadvertently download malicious software or be directed to fraudulent websites.
There are various forms of malvertising attacks, ranging from those that require user interaction (like clicking an ad) to more sophisticated ones that exploit vulnerabilities in browsers or plugins (often referred to as “drive-by downloads”). See an example here.
To protect against malvertising, it’s essential to keep software, browsers, and plugins up to date, utilize reputable ad-blockers, and maintain updated security software.