I tapped on one of the cards in Google Now, which took me to breitbart.com. A few seconds later, I got redirected to cinemobi.club and was told that I signed up for a paid subscription to that web site, which was immediately followed by an SMS saying:
FreeMsg:You've subscribed to Cinemobi for £1.99/week.Free for first 24hrs. Unsubscribe? send STOP CINEMOBI to 80206.Need help? Call 08009247988
How is this even possible? I didn't enter my phone number and I'd never entered any personal information in this browser (or Chrome) because I only use Firefox, except when opening a link in Google Now because they don't honour my browser preference by default.
Here's the link I opened originally: http://www.breitbart.com/national-security/2017/04/13/venezuela-socialist-mob-assaults-archbishop-caracas-holy-thursday/
I'm using a Nexus 5X with the latest patches.