[Milad]

1- Everyone knows that this hack adds credits in the footer, and is free to remove them.
2- How can you make such an accusation? My website (Syrian Medical Society) is reputable website, and have never been as a distribution for malwares.
Here are what google says about it:
safe browsing
unmask parasites says: This page seems to be <suspicious> because of the following line:

document.write('<marquee onmouseover="this.stop()" onmouseout="this.start()" direction="right" scrollamount="3" scrolldelay="20" class="smallfont">آخر ما نُشر لدينا&nbsp;&nbsp;&nbsp;??&nbsp;&nbsp;&nbsp;<a href="http://www.syrianmeds.net/forum/topic12165-newpost.html" target="_blank" class="smallfont">الفيزيولوجيا المرضية</a>&nbsp;&nbsp;&nbsp;??&nbsp;&nbsp;&nbsp;<a href="http://www.syrianmeds.net/forum/topic12162-newpost.html" target="_blank" class="smallfont">جراحة 3</a>&nbsp;&nbsp;&nbsp;??&nbsp;&nbsp;&nbsp;<a href="http://www.syrianmeds.net/forum/topic12160-newpost.html" target="_blank" class="smallfont">دوري علامات الطب سنة تانية</a>&nbsp;&nbsp;&nbsp;??&nbsp;&nbsp;&nbsp;<a href="http://www.syrianmeds.net/forum/topic12159-newpost.html" target="_blank" class="smallfont">داخلية 4</a>&nbsp;&nbsp;&nbsp;??&nbsp;&nbsp;&nbsp;<a href="http://www.syrianmeds.net/forum/topic12158-newpost.html" target="_blank" class="smallfont">داخلية 2</a>&nbsp;&nbsp;&nbsp;??&nbsp;&nbsp;&nbsp;<a href="http://www.syrianmeds.net/forum/topic12157-newpost.html" target="_blank" class="smallfont">التشريح المرضي العام</a>&nbsp;&nbsp;&nbsp;??&nbsp;&nbsp;&nbsp;<a href="http://www.syrianmeds.net/forum/topic12156-newpost.html" target="_blank" class="smallfont">أدوية 1</a>&nbsp;&nbsp;&nbsp;??&nbsp;&nbsp;&nbsp;<a href="http://www.syrianmeds.net/forum/topic12155-newpost.html" target="_blank" class="smallfont">تشريح 2</a>&nbsp;&nbsp;&nbsp;??&nbsp;&nbsp;&nbsp;<a href="http://www.syrianmeds.net/forum/topic12149-newpost.html" target="_blank" class="smallfont">الصحة تطلب من الصيادلة سحب عدد من المستحضرات الدوائية لمخالفتها للمواصفات</a>&nbsp;&nbsp;&nbsp;??&nbsp;&nbsp;&nbsp;<a href="http://www.syrianmeds.net/forum/topic12147-newpost.html" target="_blank" class="smallfont">ألم شديد في القدم</a></marquee>');

Which prints the marquee section, without causing the page to fail in the XHTML validation.

So please, before you make such an accusation, have the evidence that supports your claim.