In this post, i am trying to explain how to detect virus in the site. Most of the sites attacked with small script is append at end of page and before body tag. Another type virus is add iframes in the code. This virus mostly attacked for blogs and forums.
If you are using firefox, try to install firebug addon. If we installed addon, run the firebug tool it represent the red marked url will display in the toolbar. Once check the below image complete information: