Hundreds of weird entries in apache2's access log

Question

I have just noticed hundreds of strange entries in my access.log in /var/log/apache2, they all look like this:

173.193.233.143 - - [26/Jun/2011:13:50:24 +0400] "GET http://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/www.bing.comhttp://www.bing.com/search?q=from+%2findex.php?showuser%3d+%22Comments%22+6&filt=all&first=41&FORM=PORE HTTP/1.0" 200 42542 "http://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/google.comhttp://google.com/www.bing.comhttp://www.bing.com/search?q=from+%2findex.php?showuser%3d+%22Comments%22+6&filt=all&first=41&FORM=PORE" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322; XMPP Tiscali Communicator v.10.0.2; .NET CLR 2.0.50727)"

Anyone has an explanation for this strange behaviour?

Answer 1

That will be infected machines scanning to see if your machine is vulnerable to the security fault used to infect those machines, so they can spread the infection to you.

If you are patched up-to-date then you probably have nothing to worry about - this sort of thing is seen all the time (I still occasionally see attempts to scan for ancient flaws in PHP and IIS+ASP, even to machien not running those servers/services).

The "200", if that field is the response code rather than something else like the request size, implies that you server send something other than an error back in response to the request, so it might be worth requesting that URL yourself to see what response you get.