Odd things in server logs

[HaLo2FrEeEk]

I'm not sure this has to do with PHP directly, but the page in question is a PHP one, so if this is in the wrong place could a mod please move it.

I was going through my server logs and I have been frequently seeing more and more pages with this URL, or one like it, in my "Failed Referrers":

http://www.infectionist.com/forum/index.php+++++++++++++++++++++++++++Result:+%E8%F1%EF%EE%EB%FC%E7%EE%E2%E0%ED+%ED%E8%EA%ED%E5%E9%EC+%22abrawnloxTrow%22

I urldecode()'d the string and it doesn't come out to anything readable. I'm getting worried about it because I just found two files in my template directory that were both exploits:

eval(gzinflate( base64_decode(" ...")));

With the "..." being a VERY long string that decoded to a PHP page that would be eval()'d and give someone complete access to my server, including searching for config files, htpasswd files, executing shell commands...the works.

Does anyone have any idea what this strange URL means? I know it was in the failed referrer section, but still...

[JKing]

Is it a malformed link coming from another website?

[HaLo2FrEeEk]

Not that I can tell, it definitely looks like an exploit attempt, but it aso looks like it failed since it's in the failed referrers section.

[JKing]

Is it consider a failed referrer because it has a query string attached or because it has come from another site?