Using a Campaign Source Filter is great for blocking spam referrals quickly, but if your looking for something more maintainable you should use valid hostnames. When using campaign filters you will have to block everything one by one and the spam referrals will have already hit your data.
- Go to the admin tab
- Select the view from the drop down you want to filter
- Click on filters
- Add new filter
- Add a filter name to remember the filter
- Filter type custom
- Select exclude
- Filter field as campaign source
- Paste in spam URL for filter pattern
It’s important to remember that these effects will take 24 hours or more to show as it will block referrals from that URL in the future from being added to your data.