Just a few thoughts about an interesting behavior of a black-hat SEO doorway.
Typically hackers create doorways on compromised sites to make search engines rank them for certain keywords and then, when searchers click on the links in search results, those doorways redirect them further to a site that hackers really promote. Sometime that redirect may go through some TDS (traffic directing service) but the whole scheme remains pretty much the same:
Search results -> doorway -> beneficiary site
Today, when doing a backlink research of one of such pharma doorways, I encountered a different scheme — a one with a loop.