Strange GET requests in logs

I'm getting the following GET requests in my apache logs:

109.230.251.14 - - [29/Mar/2011:16:28:18 +0100] "GET http://209.191.92.114/config/pwtoken_get?login=jackmcphee232&src=ygodgw&passwd=e59e2240415e6f1aba3da72b8f189f4e&challenge=9TbU_9yfZhKmzlHtK9X4OkQlesTH&md5=1 HTTP/1.0" 404 1226 "-" "-"

Any idea what it could be and how is that possibly a get request? That IP address seems to point to Yahoo! I'm very confused.

I had the same issue. After a long search I found this wiki article that explains what's going on pretty well.

http://wiki.apache.org/httpd/ProxyAbuse

Sadly, it's just one of the many automated vulnerability tests constantly peppering web servers these days.