Page Trojan problem of principle. . .

Customer's site is often linked to Trojan, is a javascript code,,, src link to another Web page, such as xxx.asp …Well, I would like to know, in general what happens xxx.asp page? How the hacker through xxx .asp page to the client computer to attack it? best to give a detailed code of a simple example …Thank you!

Is to spread Trojan WEB space first, to establish a connection …someone clicks the link they would have got …

When you click on that page, he will address the direct download link to a Trojan! ! ! ! !