The remote host has a backdoor installed
The remote web server is infected with JS.Scob.Trojan or Download.Ject Trojan. This Trojan installs malicious code on all web pages and infects clients as they browse the server. Specifically, the Trojan's dropper sets it as the document footer for all pages served.
Stop the IIS server and use an Antivirus product to remove the Trojan. Consider re-installing the operating system.