The user could also be running the command inline somehow or deleting the file when they log off. Check who was logged onto the server at the time of the attack to narrow down your search. I like the split the users idea, though it could be several iterations to narrow down the culprit. -----Original Message----- From: Ronald Cotoni [mailto:setient@gmail.com] Sent: Tuesday, February 23, 2010 3:20 PM To: Paul Stewart Cc: nanog@nanog.org Subject: Re: Security Guideance Quick suggestion BUT you may want to have Parallels look into it if you can't seem to find it since you pay for the support anyways. You may also want to check to see if it is a cron job that is doing it (if the machine was root kitted, you may have accidentally copied a cron job over. Another suggestion would be simply move half the accounts to one server and half to another and see if it ddoses again and keep doing that until you find the problem account. On Tue, Feb 23, 2010 at 2:46 PM, Paul Stewart <pstewart@nexicomgroup.net> wrote:
Hi folks...
We have a strange series of events going on in the past while.... Brief history here, looking for input from the community - especially some of the security folks on here.
We provide web hosting services - one of our hosting boxes was found a while back with root kits installed, un patched software and lots of other "goodies". With some staff changes in place (don't think I need to elaborate on that) we are trying to clean up several issues including this particular server. A new server was provisioned, patched, and deployed. User data was moved over and now the same issue is coming back....
The problem is that a user on this box appears to be launching high traffic DOS attacks from it towards other sites. These are UDP based floods that move around from time to time - most of these attacks only last a few minutes.
I've done tcpdumps within seconds of the attack starting and to date been unable to find the source of this attack (we know the server, just not sure which customer it is on the server that's been compromised). Several hours of scanning for php, cgi, pl type files have been wasted and come up nowhere...
It's been suggested to dump IDS in front of this box and I know I'll get some feedback positive and negative in that aspect.
What tools/practices do others use to resolve this issue? It's a Centos 5.4 box running latest Plesk control panel.
Typically we have found it easy to track down the offending script or program - this time hasn't been easy at all...
Thanks,
Paul
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