“Malvertising” comes from a combination of “malware” and “advertising”, and includes taking advantage of online advertisements to spread malware or divert users to malicious websites. It is a type of cyber-attack that injects malicious code into legitimate-looking online advertisements of well-known online publications or even on social media. Believing these to be genuine sites, internet users either load the webpage or click on the ad, which downloads malware onto their devices.
Malvertising is a significant problem worldwide and has acquired increasing prevalence across the web.
How does malvertising work?
The typical strategy for malvertisers begins with purchasing ad space from publishing networks and submitting clean advertisements for a while to gain authenticity. After a few weeks, criminals switch their legitimate ads for ones infected with malware, which get communicated across any number of sites a publisher or network is working with.
These misleading ads can hamper a computer with malware in two ways:
A pre-click malvertisement can be implanted in the main scripts of the page. They can start drive-by-download on visiting the malvertising-loaded site. A drive-by-download is a download in which a user does not need to click on any link and start the download. When a user visits the webpage, the malware begins downloading automatically in the background.
For a post click malvertisement, it infects a computer when a user clicks on the ad to see the advertisement and the user is redirected to a malware-infected website.