Re: Help please

[Chris Wilkes <cwilkes () ladro com>]

On Sat, Feb 02, 2002 at 02:41:05PM -0500, Ryan Hairyes wrote:
> Hello all.
>
> I am having some trouble and would like to know if someone can help me out.
> Right now my mailserver (RedHat 7.2) is being used by unwanted guest to 
> attack adult sites via port 80 (Apache 1.3.20).  When I run a netstat -an
> on my system I can "see" them connected to my machine.  I have snort and 
> have run that as well and sure  enough they are there.  It seems as though
> they are using my apache to do brute force password cracking on these adult
> sites.  Thanks in advance.

What I've done to avoid the possibility of this is to have a web proxy
server (see http://www.squid-cache.org/ for one) installed on the
network that all outbound port 80 traffic has to go through in order to
get outside my network.

But instead of following the examples in the iptables (the linux
firewall / nat software) of making it a transparent proxy where all
traffic is forceably routed through it I've instead elected to put in
the proxy server settings on my programs manually.  I then drop all
outbound port 80 traffic except that coming from the proxy server.

This should be able to stop most virus / cracker programs that do a
simple outbound HTTP request as they probably aren't proxy server aware.

As for your immediate course of action I would take that computer off
your network, plugging the ethernet cable out is the easiest way, and
work on getting a secondary mail server up and running so that you can
at least get email.

Also what you have is probably a program that is acting as a web
browser, as a web server like Apache can't really launch an attack.  Can
you block all outgoing traffic from the mail server except for port 25,
SMTP (mail) traffic?

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