There’s been numerous reports of websites receiving mystery traffic that includes RK= and RS= directories that don’t exist on the website.
For example, if a page was www.domain.com/folder/article
You would see
in the logs, which of course is a 404 – page not found.
Is the traffic malicious?
To date there has been no reason to believe this traffic is related to malicious activities such as hacking, DDOS etc.
What is causing this traffic?
The best explanation is it is come from either web-scrapers or search engine spiders incorrectly using Yahoo! Search result.
Is there a problem with my website?
The only problem could be all the 404 traffic you will see in your logs and analytic.
What can I do to stop it?
You can’t stop it, anyone is free to request what ever pages they want from your website – whether they exist or not.
But you can redirect the traffic to the correct path. This can be done using the following in your htaccess file
RewriteEngine On RewriteRule ^(.*)RK=0/RS= /$1 [L,NC,R=301] RewriteRule ^(.*)RS=^ /$1 [L,NC,R=301]
Stack Exchange Webmasters: http://webmasters.stackexchange.com/questions/58871/strange-entry-in-access-log-containing-rs/68072#68072