Bad Headers - Malware, Plugin or?

We're seeing a bunch of requests that look like they were altered and not the original request from the client machine. It could be virus software, malware, proxy servers, caching servers on networks - who knows. Hopefully it is not an evil plugin or someone spying on network traffic.

Here are some of the IP addresses that had this weird header issue recently:

11/23/2009 8:57:02 PM 76.104.180.131 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.0.3705; .NET CLR 1.1.4322; Media Center PC 4.0)
11/22/2009 8:32:58 PM 71.234.217.226 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; FunWebProducts; Comcast Install 1.0; GTB6; .NET CLR 1.1.4322)
11/22/2009 7:39:31 AM 63.226.217.184 Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; .NET CLR 1.0.3705; .NET CLR 1.1.4322; Media Center PC 4.0; .NET CLR 2.0.50727; IEMB3;
11/22/2009 7:10:29 AM 173.66.61.177 Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; GTB6; .NET CLR 1.1.4322; InfoPath.1)
11/21/2009 6:57:42 AM 67.40.212.30 Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; .NET CLR 1.0.3705; .NET CLR 1.1.4322; Media Center PC 4.0; .NET CLR 2.0.50727; IEMB3;
11/20/2009 5:11:09 PM 67.161.88.107 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Comcast Install 1.0; GTB6; .NET CLR 1.1.4322)
11/18/2009 4:54:27 PM 209.91.40.80 Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/532.0 (KHTML, like Gecko) Chrome/3.0.195.33 Safari/532.0
11/17/2009 9:02:20 AM 216.254.19.10 Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.15) Gecko/2009101601 Firefox/3.0.15 (.NET CLR 3.5.30729)
11/15/2009 6:11:47 PM 98.247.251.172 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; MathPlayer 2.10; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729;
11/15/2009 10:06:02 AM 76.22.123.218 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; GTB6; .NET CLR 1.1.4322)
11/14/2009 11:45:21 AM 98.174.211.179 Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; .NET CLR 1.0.3705; .NET CLR 1.1.4322; Media Center PC 4.0)
11/14/2009 9:46:00 AM 174.113.26.207 Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.15) Gecko/2009101601 Firefox/3.0.15 GTB5 (.NET CLR 3.5.30729)
11/14/2009 4:06:48 AM 96.18.203.27 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; FunWebProducts; GTB6; .NET CLR 1.1.4322)
11/13/2009 9:16:07 PM 67.171.37.175 Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.1) Gecko/2008070208 Firefox/3.0.1
11/13/2009 8:22:26 PM 24.113.197.5 Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; GTB6; .NET CLR 1.1.4322)
11/11/2009 10:31:57 PM 96.26.232.125 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; GTB6; .NET CLR 1.1.4322)
11/11/2009 12:46:39 PM 98.237.128.105 Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; GTB6; .NET CLR 1.1.4322; .NET CLR 2.0.50727; Zune 3.0; .NET CLR 3.0.4506.2152; .NET CL
11/10/2009 8:52:51 AM 71.37.54.113 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; GTB6; .NET CLR 1.0.3705; .NET CLR 1.1.4322; Media Center PC 3.1)
11/8/2009 7:52:24 PM 75.111.19.240 Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.15) Gecko/2009101601 Firefox/3.0.15
11/7/2009 10:50:38 PM 71.227.255.37 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)
11/7/2009 10:50:12 PM 71.227.255.37 Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.15) Gecko/2009101601 Firefox/3.0.15 (.NET CLR 3.5.30729)
11/7/2009 5:45:34 PM 24.17.66.221 Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; GTB6; .NET CLR 1.0.3705; .NET CLR 1.1.4322; Media Center PC 4.0; Zango 10.3.85.0)
11/7/2009 4:03:05 PM 71.227.155.229 Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.15) Gecko/2009101601 Firefox/3.0.15 (.NET CLR 3.5.30729)
11/7/2009 1:00:12 PM 67.185.148.232 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; GTB6; .NET CLR 1.1.4322; .NET CLR 2.0.50727; Zune 3.0; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)
11/5/2009 10:59:14 PM 67.171.34.181 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; GTB6; .NET CLR 1.0.3705; .NET CLR 1.1.4322; Media Center PC 4.0)
11/5/2009 6:30:41 PM 66.8.185.228 Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)
11/5/2009 4:42:05 PM 67.171.34.181 Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; GTB6; .NET CLR 1.0.3705; .NET CLR 1.1.4322; Media Center PC 4.0)
11/5/2009 4:09:26 PM 67.171.34.181 Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.5) Gecko/20091102 Firefox/3.5.5
11/5/2009 2:09:18 PM 67.171.34.181 Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; GTB6; .NET CLR 1.0.3705; .NET CLR 1.1.4322; Media Center PC 4.0)
11/5/2009 1:55:29 PM 71.194.250.75 Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.15) Gecko/2009101601 Firefox/3.0.15
11/3/2009 5:49:21 PM 24.18.214.26 Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.4) Gecko/20091016 Firefox/3.5.4 (.NET CLR 3.5.30729)
11/3/2009 9:24:01 AM 98.232.12.107 Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 3.5.30729)
11/3/2009 9:21:40 AM 96.26.255.77 Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 3.5.30729)
11/3/2009 9:05:57 AM 24.18.227.177 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; GTB6; .NET CLR 1.1.4322)
11/3/2009 7:07:03 AM 97.113.236.36 Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; GTB6; .NET CLR 1.1.4322)
11/2/2009 5:29:23 PM 207.172.136.97 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.1.4322)
10/30/2009 11:44:14 PM 67.183.56.30 Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; GTB6.3; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30
10/30/2009 11:44:13 PM 67.183.56.30 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; GTB6.3; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30
10/30/2009 11:44:27 AM 131.191.65.125 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; GTB6; .NET CLR 1.1.4322)
10/27/2009 6:28:27 PM 71.112.251.46 Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; GTB6; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.3072
10/27/2009 6:28:27 PM 71.112.251.46 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; GTB6; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.3072
10/25/2009 8:25:20 PM 174.21.95.103 Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 3.5.30729)
10/24/2009 4:36:59 PM 75.92.212.208 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; GTB6; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; Zune 4.0)
10/22/2009 3:25:26 AM 69.85.109.91 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; GTB6; .NET CLR 1.1.4322; .NET CLR 2.0.50727)
10/21/2009 12:55:41 PM 24.16.92.189 Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; GTB6; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)
10/19/2009 5:03:33 PM 76.28.193.198 Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 GTB5
10/17/2009 10:07:48 AM 24.18.214.26 Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 3.5.30729)
10/13/2009 12:39:53 PM 98.225.57.246 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; GTB6; .NET CLR 1.1.4322; WinTSI 10.10.2009)
10/11/2009 10:19:35 AM 209.143.5.210 Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; GTB6; .NET CLR 1.1.4322; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; .NET CLR 2.0.50727)
10/10/2009 1:47:04 PM 64.136.26.227 Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.0.3705; .NET CLR 1.1.4322; Media Center PC 4.0; InfoPath.2; .NET CLR 2.0.50727; .NE
10/6/2009 7:59:57 PM 63.226.219.30 Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; GTB6; .NET CLR 1.0.3705; .NET CLR 1.1.4322; Media Center PC 4.0; .NET CLR 2.0.50727; .
10/6/2009 1:52:07 PM 64.146.149.194 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.1.4322)
10/5/2009 5:20:18 PM 67.160.3.12 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; GTB6; .NET CLR 1.0.3705; .NET CLR 1.1.4322; Media Center PC 3.1; .NET CLR 2.0.50727; .
10/5/2009 4:57:52 PM 98.232.9.64 Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.11) Gecko/2009060215 Firefox/3.0.14
10/4/2009 5:28:20 PM 75.92.211.243 Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; GTB6; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)
10/3/2009 8:40:36 PM 98.117.109.217 Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.14) Gecko/2009082707 Firefox/3.0.14 (.NET CLR 3.5.30729)
10/3/2009 4:45:31 PM 71.227.155.229 Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.14) Gecko/2009082707 Firefox/3.0.14 (.NET CLR 3.5.30729)
10/2/2009 3:56:39 AM 161.53.179.226 Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322)
10/2/2009 3:55:57 AM 161.53.179.232 Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322)
10/1/2009 8:36:55 PM 67.171.39.2 Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.14) Gecko/2009082707 Firefox/3.0.14
10/1/2009 4:49:42 PM 70.193.96.120 Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; GTB6; .NET CLR 1.1.4322; .NET CLR 2.0.50727; InfoPath.2; MS-RTC LM 8)