Problem URL's containing "Hidden-Referrer"
Some visits to your site will display an invalid referring URL that contains "Hidden-Referrer".
This happens when the visitor is using Zone Alarm Pro. This is a "personal privacy" product that is installed on the client computer. A built-in proxy server modifies all web requests, replacing the true referring URL with the string "Hidden-Referrer". Because of the way this is implemented, the referring URL is often logged by AXS as the URL folder following by that string, i.e. "http://www.xav.com/perl/Hidden-Referrer".
It has been reported that Symantec's Norton Internet Security does the same thing.
There are no work-arounds at this time. When visited by a site using this cloaking tool, much of the information about this visit will be false, such the referrer and browser name. In most cases, though, the local page visited, the time, and the fact that the visit took place will be accurate.
"Problem URL's containing "Hidden-Referrer"" https://www.xav.com/scripts/axs/help/1514.html