This is generally a symptom of a hacked site using a server side
“referer exploit.” As you have noticed, the redirects occur only when
trying to access the site by way of a search engine result. It does
not occur when you type the URL manually or access the site from a
link from another site. If you use a different search engine, you will
probably see the same thing.
http://groups.google.com/group/Google_Web_Search_Help-Content/browse_thread/thread/2272f51ffa221d9b
An example of the “sattan-extra” codestring in wp-blog-header.php: part-of-sattan-code.txt
This textfile is decoded. You can see the course of events.
