Recalling actual trends in online advertizement, researchers at the University of Washington found out that already one percent of all web pages requested by users are changed in content during their transit from web server to the user, sometimes with harmful content. The study has been executed with 50.000 clients and discovered the mentioned altering phenomena, including ad injections and problematic security features like ad-blocking that sometimes were even increasing trouble than eliminitating it. In their study, the authors present an alternative to switching to https, what would be a costly solution to prevent ad injections. Whether web tripwire is the measurement of choice is yet to be seen. (Source)