You use the app Spotify on your Mac or PC (with Windows or Ubuntu)? So be careful!
As one user reported on the Spotify Community (kind of official forum for the service), there is something very strange about player his official. Apparently the advertisements that are shown in the software (for those who are not subscribers) are making the system's default browser visit some sites automatically; such URLs, then, are responsible for disseminating malware regardless of the user's wishes and this, as I said, on macOS, Windows or Linux.
PSA: uninstall Spotify free, their ads are plagued with malware right now. pic.twitter.com/DUOqDrnDUZ
– Volp (@VolpRS) October 5, 2016
Delete Spotify free, his ads are infested with malware at the time.
In short: if your browser is behaving in a strange way, good to be suspicious. If everything is still normal by now, don't take any chances and try to delete the Spotify app until everything is resolved by the company she has already stated that she is investigating the matter.
It is worth noting that this is not the first time that something like this has happened. A few years ago, certain advertisements installed fake antivirus software on the affected computers (at that time, however, the problem only happened on Windows PCs).