Site hacked

Just installed wordpress 3.4.2 for http://www.kedahtimes.net, within a week the site already hacked.

We Are Surabayahacker , We Come To Test Your Security , We Are Not Cracker So Not Data Deleted, Please Patch Your Site
Thanks To : Brian Kamikaze
Katon A.k.a Gembel Elite
Om Jin
Egar [ 0m Ch0c0]
BlueFrozen A.k.a Anu
Trisna A.k.a Gembel Ningrat
Mas Andy A.k.a Meninbox
Hilmi A.k.a Drevo
Ihsan Ardiansyah
And All Surabayahacker Member
Regards : Surabayahacker Team & I am Brian Kamikaze

Any idea which patch i did not update?