iFrames are a browser feature that allows websites to deliver content from a remote website within a frame on a page. Theyve become a popular way to dump many varieties of malware onto unsuspecting web surfers. iFrames were the distribution mechanism used to create a large population of machines infected by the form-grabbing malware variant dubbed Gozi. Some entrepreneurs are buying up domains just to host the iFrame code and then hustle to direct traffic to their sites. iFramers also inject their iFrames into legitimate websites that have vulnerabilities which allow it to happen.”]
Source: https://www.csoonline.com/article/2123333/death-by-iframe.html