After going through Google Analytics in November 2015, I noticed a few domains that I did not recognize. There were normal referrers like Google, Reddit, Anandtech, Hardforum, Ars Technica, various vendor sites and etc. Then at the very tail, there were a few completely indistinguishable sites. I almost clicked on the referring URL in Google Analytics when I decided to try something a bit different. I used a dormant domain name that had not been used in some time. I made a small HTML site with Google Analytics tracking code and waited. To my surprise, it started getting traffic. Here is a bit on Google Analytics spam sites that we learned about in the process.
Getting a Sample of Google Analytics spam Referrers
This was the easy step. We first setup a simple virtual machine running Nginx with a test domain name that I use from time to time for development. Since we are just serving static content, there is no need to install php5-fpm or other additions to the stack. Next, we built a responsive HTML5 site. By built, we just used a development template we had with no real functionality. We setup our DNS record to point to the new server and just sat back and waited for a few days. The important aspect here is that there was no content to scrape, just a landing page to trigger Google Analytics tracking.
What we found
We had a hypothesis that the site would see traffic. So we waited for 40 days to look at the tracking. With no back links a the site that did not show up in the indexes of Google or Bing when searching for the exact domain text string, there was no way for this site to get legitimate traffic. Yet when we looked again after 40 days, there were 305 sessions recorded in the trailing 30 days. Some days even saw in excess of 25 sessions per day.
We saw a number of domains with traffic2cash.xyz and share-buttons.xyz being some of the highest frequency referrers.
So what are sites like traffic2cash.xyz, share-buttons.xyz, and the perhaps more tellingly named build-a-better-business.2your.site? They are sites that script referrals in order to advertise to Google Analytics (and presumably other tracking software) website owners. The hope with this activity is that you see the site in Google Analytics and then click-through to get served ads or whatever else the site is serving to the website owner.
This is certainly one of the more novel advertising methods I have seen. Generate traffic on a site solely to target the webmaster. I remember a former colleague who started a blog, installed Google Analytics and was excited to see traffic. His blog actually had content and was legitimate unlike our test site. Remembering the feeling of being a new webmaster and seeing the first tiny bits of traffic was very exciting. As a new webmaster I probably would have clicked on these links, albeit in a throwaway virtual machine.