The Infinite Brief

This is not the first time filters have been used for malicious purposes. In 2018 a list maintainer added a filter for political reasons that blocked various union web sites in Finland that were conducting protests.

With ad blockers having a a user base of over 10 million installs, if malicious scripts were injected it would have a huge impact as they could perform unwanted activity such as stealing cookies, login credentials, causing page redirects, or other unwanted behavior.