suspicious CGi file

[samibdr]

Hello,
recently someone installed a script on our websites and it seems like it doesnt want to go away. everytime we remove the script from the code it comes back after a few days. we are examining all the files in our websites and found this file:

hostchk.cgi

the file outputs are:

System info
-----------

linux
Linux host248.hostmonster.com 2.6.22-19_1.BHsmp #1 SMP Thu May 22 08:08:32 MDT 2008 x86_64 x86_64 x86_64 GNU/Linux


Perl modules
------------

strict .......................... Ok
Sys::Hostname ................... Ok
POSIX ........................... Ok
Errno ........................... Ok
IO::Socket ...................... Ok
IO::Select ...................... Ok

Local server test
-----------

Ok

DNS client test (194.173.175.100)
-----------

Ok

SMTP Client test (smtp.mail.ru)
-----------

Error > Can't connect > Connection refused



Could someone tell me what is this file?

Thanks

[sowhat-x]

It's spam-related...check this out to get an idea:
http://www.google.com/search?hl=en&q=Direct+Mailer+hostchk.cgi&btnG=Google+Search&aq=f&oq=