I was at work today and my virus alert kept blocking every link I clicked in Google, even ones that I knew were valid. I soon noticed that every link in Google was going to www.google.com/go?XXXXXX. The XXXXXX was a different number for each link.
I thought this was a bit odd, so started to do some checking with my co-workers and none were having this same behavior from Google. I then tried IE and at first didn't have the issue, but then a few seconds later, all the links updated to the same suspicious Google URLs. I was now suspecting a virus or malware had made it on to my pc. I went to another pc and did some googling and found that there is a go.google.com malware/trojan that has this behavior. It modifies the host table on the pc to point google.com to an AD server so every google link opens a third party ad. Supposedly it affects Bing, Yahoo, and MSN as well.
To get rid of it, I ran the Malwarebyte's Anti-Malware (Free version, Download Now link), which found 4 infected files, one of which was a replacement host table file.
I'm still not sure how it got on my pc. I haven't installed any new software and usually will kill a browser that has any weird pop-ups. So must have been a windows bug or something. I ran the latest window's update and had them all. My Firefox was a patch behind, so could have been that.
Just wanted to let you all know what I was experiencing in case anyone else was having the issue and how to fix it.