On Monday 22 December 2003 08:16 pm, Ken wrote:
> Hello All,
>
> Please be patient with me, I am new to the Linux world and I am not a
> security expert.
>
> I built a uClibc firewall version 2.0 Linux firewall kernel 2.4.20 from the
> image Bering-uClibc_2.0_img_bering-uclibc-1680.exe and I have been
> compromised.  I have included a lot of information here because I need to
> know how the hackers compromised this machine and I want to give you as
> much information as you need to help me figure it how. 

You did a pretty good job of showing the logs of packets that have been
dropped (that never got through the firewall). Believe it or not, it would be
next to impossible to relay spam or send it from a compromised LEAF box.

First of all, you would have to enable some form of login to the outside,
which isn't available unless you opened the firewall to accept such requests.
Second of all, the likely culprit of spewing emails is Outlook/Outlook-Express
on a Win32 machine with a virus which can very easily happen if you use
IM, chat, or P2P applications on the client-side (LEAF doesn't content-filter
traffic).
 
I would check your client machine(s) for possible infection first, then find 
sort of proof that the LEAF firewall was compromised (which likely won't
be found in any logs). Remember, your clients will show the external ip
of the firewall when sending traffic because of the masquerading done by
the firewall. Your local ip's of the client machines will/should never be sent
from the firewall..... which is the entire point of masquerading/NAT.

If your LEAF firewall has actually been compromised, it would be the first
that I know of in memory. 
-- 
~Lynn Avants
Linux Embedded Appliance Firewall Developer
http://leaf.sourceforge.net
http://guitarlynn.homelinux.org:81


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