I see repeated requests like these in my Apache Access Logs and they have been eating up all my CPU.

I have a normal WordPress installation. All i changed in the Apache Configuration was changing the DocumentRoot from /var/www/html to /var/www for both ssl and the default configuration.

Also, the file referenced in the requests(updatedll.jpeg) does not exist on my server and also isn't referenced in the source code served by any page of the web application.

Could this be a security threat? What are these actually and what can i do to stop them.

I changed the ip address of my server. They still kept coming. Meaning that somebody is actually hitting the domain name and not the ip address.

Why does my server send a 301 for these requests? Shouldn't it be sending a 404? Is it because Wordpress is installed in my root directory and the .htaccess file present for Wordpress is sending a 301 redirect?

My disk access logs also seem to have high peaks intermittently. But nobody is actually accessing the site. I see no access logs except these below.

Also, i see that all the requests seem to be coming from one of the following 5 ip addresses.

201.4.132.43 - - [05/Jun/2014:07:35:08 -0400] "GET /updatedll.jpg HTTP/1.1" 301 465 "-" "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; WOW64; Trident/4.0; BTRS103681; GTB7.5; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; InfoPath.2; OfficeLiveConnector.1.3; OfficeLivePatch.0.0; AskTbATU3/5.15.29.67612; BRI/2)"

187.40.241.48 - - [05/Jun/2014:07:35:08 -0400] "GET /updatedll.jpg HTTP/1.1" 301 465 "-" "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; GTB7.5; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)"

186.56.134.132 - - [05/Jun/2014:07:35:10 -0400] "GET /updatedll.jpg HTTP/1.0" 301 428 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322)"

71.223.252.14 - - [05/Jun/2014:07:35:13 -0400] "GET /updatedll.jpg HTTP/1.1" 301 465 "-" "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; BTRS31756; GTB7.5; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; .NET4.0C; .NET4.0E; InfoPath.2)"

85.245.229.167 - - [05/Jun/2014:07:35:14 -0400] "GET /updatedll.jpg HTTP/1.1" 301 465 "-" "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; Trident/7.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; MAAU; .NET4.0C; BRI/2; .NET4.0E; MAAU)"