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RE: security scenario
From: "Trevor Cushen" <Trevor.Cushen () sysnet ie>
Date: Fri, 31 Jan 2003 19:03:36 -0000

What about this for a cat amoung the pigeons!!!

Physical security is in place, root access is via console only (all
previously discussed)

A user can gain access via the lan (as part of their job) and places
netcat (which is most likely already there on most Linux installs
anyway).  They then schedule overnight a dd of the system disk to a disk
in their machine over the network (very easy to do)  What priviledges do
they need??  I must check this but I have a feeling they will have
access to /dev files and also the /bin files where netcat and dd are (or
/sbin).

Now they can bring the newly cloned disk home and in their own time
brute force root passwords, or boot via CDROM to by-pass the password
and gain access to data.

Very much possible and infact quite easy to do (I use it for forensics
investigations where I can't shutdown the machine), clone a machine over
a network connection.

Your physical server room security is useless and also your root at
console only security.  Your bios passwords are useless here too as is
your grub password.

The point I am making here is that you have to match the solution to the
environment so there will never be a true solution for all because all
environments are different.

Trevor Cushen
Sysnet Ltd

www.sysnet.ie
Tel: +353 1 2983000
Fax: +353 1 2960499



-----Original Message-----
From: theog [mailto:theog () theog org] 
Sent: 31 January 2003 00:23
To: Chris Berry; security-basics () securityfocus com
Subject: Re: security scenario


Well , I think that instead of dealing with how many layers one can
install (and taking the time to install them) it is better (IMHO) to
invest the time in making the important layers secure. having more
layers won't increase your security level if you spent all the time in
installing those same layers , whatmore , you have more then CDROM and
Floppy to boot with (USB dev , etc...). I wouldnt use a grub password ,
or a bios password , as forgeting those , will cause more harm then the
security benefit they provide ,writing them down or putting weak
passwords is simply not worth the trouble .


TheOg

----- Original Message -----
From: "Chris Berry" <compjma () hotmail com>
To: <security-basics () securityfocus com>
Sent: Wednesday, January 29, 2003 9:44 PM
Subject: Re: security scenario


From: "theog" <theog () theog org>
I agree , in my opinion , if someone got to the machine's keyboard , 
be it phisically or via a remote console device , he can do virtually

anything, in fact, the simplest thing to do (if I wanted to change 
the root for a machine I dont have the password for) is to boot with 
a linux cd , mount the root partition , then do chroot , and passwd ,

so ..... no point is having a grub password for the machine if you 
have users you dont trust , with access to that machine console.

Physical access will yield root access given time, knowledge, and 
tools. That said, I still disagree, security is not one thing, it is a
compilation
of little things that add up.  No one is hack proof, but by adding 
layer after layer of complications for the attacker, you make yourself

an uninviting target, and become hack resistant.  You have to draw the

line somewhere or your administrative burden will grow greater than 
you can handle, but I believe that a grub password (or requiring root 
password for single user mode) would be a good idea as it's easy to 
setup and maintain, but makes things a little more difficult for the 
attacker (not to mention curious employees messing with things they 
shouldn't be).  I also think
bios
passwords are a good idea, sure any monkey who can open the case can 
pop
the
battery and reset it, but that's one more step they have to do, and 
around most workplaces you'll get quite a bit of unwanted attention if

you start taking your computer apart and you don't work in IT.  On top

of this, removing the CD-ROM drive and Floppy drive from any 
workstation that
doesn't
require it, is a good idea as it slows them down even further, and
requires
more knowledge, and some parts to bypass.  With these three things in
place
they'll need a screwdriver, a linux cd, a cd-rom drive, enough 
knowledge
to
open the case install the cd-rom, set the jumpers on cd-rom and IDE, 
reset the cmos, then boot up and use their linux cd to bypass your 
grub
password.
Can it be done sure, is it hard, not really for a trained person, I 
could probably do it in under 20 minutes, but how many people have 
that level of training, and can get unobserved access to the machine 
for that long? Personally I feel that would stop anything but a 
determined and knowledgeable attacker who has time and physical 
access.  If you have good physical security (locks, alarms etc.) that 
makes it even harder.  If someome is determined enough to get through 
all that there isn't any way you're going to stop him anyways, but I 
consider that a much lower order
of
probability than the kind of people who could get in without having 
those three precautions.

Chris Berry
compjma () hotmail com
Systems Administrator
JM Associates

"For Sys Admins paranoia isn't a mental health problem, its a 
marketable
job
skill."

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