On one of my DNN 5 sites I have noticed there is some HTML being generated that shouldnt be there - whilst the output it isn't visible other than on Chrome there is a series of links to an unknown site in the HTML

The HTML is appearing across both the templates that are being used and after looking at the templates I cannot see the HTML anywhere.

Googling the URLs in question I can find hundreds of sites with the same links across PHP, ASP, .Net etc and so evidently this is some form of injected code but how do I best go about finding it and eliminating it from the site?

It is on shared hosting running medium trust so only access to the server is via Helm and FTP.

The links are to fake designer goods and I know the owner of the hosting company and it certainly isnt his style. I've also looked at our other sites that are installed on the same web host but different instance of DNN and they are all fine.

I cannot see any extensions that have been added recently, all those that are there are also on the other installations of DNN which are all clean.

I dont know when these were inserted though. They dont actually display visably other than in the latest version of Chrome where they appear as a single dot which is well below the page footer so they could have been there for ages and just not noticed as I havent looked at the source.

What is the best way to find where these are coming from and delete them?

I have looked at the two skins in questions and there is no trace of the HTML that is appearing on the site.