Google analytics referral traffic "referral / 4000"

Question

We have noticed an unusually large percentage of traffic coming from sources like "referral / 4000" (it is not actually 4000, the number is more specific but in the 4000's, I don't want to be more specific unless I have to in case it is a breach of confidentiality). Sometimes there are multiple "referral / 4000" with slightly different numbers simultaneously. They account for upwards of 25% of all traffic and always result in 0 conversions. We have several other websites that do not show this traffic source.

I have performed every google search I could come up with and so has the rest of my team.

Has anybody ever encountered a similar situation?

Answer 1

This seems like bot traffic that tries to advertise a site. So the site in the referrer. They expect the analysts to go to the site to investigate, thus, getting traffic.

Unlike what it seems, generating 4000 visits with a specific referrer to a site takes about one second for a front-end script, quickly written in Chrome and launched from an average laptop with an average internet connection. It's even more performant when done through proper backend.

Now throw in a few hundreds of thousands of sites with their GA ids, spread your hit spam equally to all sites so that you still send tens of thousands hits per second, but to different sites, thus simulating organic spread of hits in time (if not the conversions, exits or bounce).

Why do this? Well obviously not everyone knows how analytics spam works, so people new to analytics would go and open the site, which is the only reason for the site to do it.

How to prevent it? There are multiple articles on how to prevent the link spam, but the best start is to ignore it. They normally only do it for newer sites and then stop in a quarter or so. You can also try filtering it out.