Got lots of spam pages, how to clean?

hello,
I just noticed that my blog has got lots of spam pages, for example

domain.com/spam-link.html

I have checked carefully my theme files, it does not contain any base64 code.
However, in the default plugin ‘Hello Dolly’ folder had a file called ‘style.php3’. Its contents are like

<?php eval (chr(101).chr(114)...

I have deleted this file. How can I clean the spam urls from my blog? Are they stored somewhere in the database? Please help me with this. Thanks