security problem - Racialist attack

Hi. Today WE saw that in index.php of all of our websites (w ww.korsansozluk.com , w ww.sinemaa.com and w ww.electroonic.com) that code which is copied below. It was inserted at the bottom of the required codes. We are wondering about whether it is a trojan attack. Because, we are a website which has a political view (democratic view).at recent time The racialists which don't like democrasy have been attacking. We want to know what to be done by us for protecting our websites. Can you please give us infos what must be done step by step. Thank you from now. see you...

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