Hacked and trying to find the culpret

I was hacked last week ,and now i have recently re-imaged my server but i still have a folder/script trying to brute force another server via my own server. so as you can see this was due to a installed website backup.

My problem is i dont have a clue how to trace the source of the attack. I have installed splunk succesfully to try and make my life easier but i dont know were to start to search and query.

For your information the server that my server is trying to hack is 188.40.55.134.[port]: SIP if this helps

my operating sys is centos 5.5 and i have plesk 9.5 running on my server.

help is needed as soon as possable as my hosting company have given me until tomorrow to sort it or they will block and shut my server.

thanks in advance

can anyone not offer any help?

get your hosting company wipe and rebuild the server.

also you should be able to submit an site backup to them and have them audit the backup before it's put back online

is there any way for me to detect the intrusion now. i just need some advice regardsless if i need to install software on the server as well some common sense steps on how to investigate and isolate the problem.

Please you help would greatly be appreciated.

thanks in advance

Does the backup that you restored include the log files from your previous installation? If the backup is infected, the break-in would have happened before the backup was made, so if the log files are intact in the backup, you might be able to find some traces there. Take a look in your /var/log directory, and see how far back the entries go.

Check the .htaccess file to see if it contains a malicious redirection........

Just reinstall everything.

Disable functions you don't need in PHP. Make sure proftpd is updated. After a few failed logins start dropping the connections with the iptables. Make sure the actual backups aren't viewable via: the web directory. Its petty ante common sense stuff.