Referrer Laundering is a technique frequently used by ill-intentioned websites to redirect traffic on to a second party, while masking the actual origin of the traffic. We see it frequently in affiliate search engine advertising - the user experience typically looks like this:
- User searches for "SampleStore"
- User clicks search ad for SampleStore.com
- The user is taken to a page on AfffilateSite.com
- The page on AffiliateSite.com loads for a split second
- The user is then redirected on to SampleStore.com
SampleStore's referrer logs and affiliate network stats show that the user came from a page on AffiliateSite.com. There is no indication that the user actually came from a search ad and many affiliate managers interpret this traffic as pure affiliate value add.
There are certainly legitimate reasons to redirect users through AffiliateSite.com. Affiliates may be uncomfortable revealing the search terms they are using to buy traffic or may desire to conduct their own ad tracking.
The two primary mechanisms for issuing redirects are server-side 301 and 302 redirects. These are the methods recommended by the W3C for redirection. Both 301 and 302 redirects keep the original referring website intact. Neither of these techniques cause 'Referrer Laundering' so we generally consider them to be 'proper'.
Improper redirects are typically used by unsophisticated webmasters who are unable to code proper redirects or by sophisticated webmasters that are laundering referrers. In search engine advertising, the vast majority of improper redirects we discover are intended to launder referrers.
Detecting Referrer Laundering
We've always monitored proper redirects and with our most recent update to PoachMark, BrandVerity is now monitoring improper redirects and is able to detect a substantial percentage of referrer laundering links.