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My server's been hacked EMERGENCY
My site is hacked and I've asked yesterday about this issue.
I've changed the FTP password, the server password. I also have change the location of the server where it use to be in the folder of MAMP now I changed it to somewhere else and it is still happening.
What happen is that all the sites being replace with .htaccess with all the redirection to some random russian site and end up forwarded to baidu.com which is Chinese search engine.
I have the most up to date Wordpress and all the plugin is disabled even I did removed them all.
First I though only one of them is being affected, but it turn out to be all the site in the same server got affected by replace the .htaccess
I don't know which step I should take to solve this problem now. I have also download my site (3.5GB) and did some search with Notepad++ and using command line like grep to find if there is any php file that is doing that kind of replacing the file and nothing really found.
I'm looking to solve this problem since yesterday and lost a lots of traffic of my site to them and I don't know what to do now.
Anyone please give me some suggestion.
I did a lots of researches and nothing really found yet.
I did chmod the .htaccess to permission 400 and they still can replace the file.

chattr -R +i ...all the files (but don't do any cache directories or WP will fail) so even root can't change them (until youchattr -R -i ...them). – Jay Jun 10 '12 at 16:59ls -la(if you have SSH access) of the Web Root (or at least give us the MOD and OWN properties of your home directory, web root, .htaccess file, and wordpress installation folder). This is so we can have a better idea of what the file permissions are of folders, etc. Also assuming that you are using Apache, what version are you running, and whatuser:groupis it running as. – Jason S Jun 10 '12 at 17:07apachefor the group and owner and that is the same for all. – Ali Jun 10 '12 at 17:09-rw-r--r-- 1 Xserve _www 236 Jun 10 22:34 .htaccess– Ali Jun 10 '12 at 17:11drwxrwxrwx 40 _www _www 1360 Jun 10 23:51 wwwthis is the root of the site. – Ali Jun 10 '12 at 17:11apachegroup and owner because for the group and owner ofapacheisXserve:admin– Ali Jun 10 '12 at 17:15wwwis World Writable (the final w in drwxrwxrwx), allowing people to overwrite things such as .htaccess. – Jason S Jun 10 '12 at 17:18chmod 775 www– Jason S Jun 10 '12 at 18:46