It took over 5 hours of surfing DCUM (I know, hard work, but someone has to do it), but I finally got redirected and captured all the traffic. I am going to put all of my findings here, not so much for the edification of our users, but to help any other website admins that might be Googling this issue:
First, despite all of the traffic I have captured and all of my efforts, there is a missing link. That is the link between Google and the beginning of the chain that I can document. So, we sort of enter this adventure in progress. I worked backward to get to where I am starting.
Somehow, my browser sent a HTTP request to
http://ad.turn.com/server/ads.js with a bunch of parameters attacked to that URL. When ad.turn.com responded, its response included an iframe (invisible HTML frame) that loaded content from
http://www.mobileadhost.com.
That caused my browser to send a HTTP request to www.mobileadhost.com. The response to that request contained another iframe that loaded more data from
http://www.mobileadhost.com.
This caused my browser to make a second HTTP request to www.mobileadhost.com. The response to that request redirected my browser to
https://sevmob.com/.
Somehow, I am not sure how, my browser also made a HTTP request to
http://ads.glispa.com. The response to the second mobileadhost.com request above did not say anything about glispa.com. However, the request to glispa.com contained the complete URL from the second mobileadhost.com request as it "referrer" in the header of the request.
The glispa.com request contained a redirect to
http://hastrk2.com/.
The response from hastrk2.com contained redirects to the Apple Appstore:
https://itunes.apple.com/ca/app/dragon-city-mobile which attempted to load Dragon City in the iTunes store. However, that failed because I wasn't really using an iPhone.
At this point, I have blocked hastrk2.com, glispa.com, mobileadhost.com, and turn.com from serving ads to us. Turn.com is a huge service and it appears that many other services use Turn in some manner. So, I don't know what the impact of blocking Turn will be. It could have a significant on our entire ad serving function. Also, blocking it might not solve the problem. I guess we just have to wait and see.