Re: Unauthorised switchport access

[Kern <timetrap () gmail com>]

Having open switchports near a comfortable sitting place (a WC) is a
major physical security risk.  Your LAN becomes a major target to
anyone who has interest (and seeing that you work for the government,
Lot's of people have an interest).

So I can go over a few ideas that will help you conceptualize the risk.

1. Unauthorized access, imagine the worst.  A contractor or other
non-governmental employ hooks up to your LAN and hits his favorite
kidde porn site.  It does not take much, getting a DHCP address is
very easy, the only hurdle that they may have to overcome is the proxy
server, which if they have any login privileges anyway will probably
already know, from there it may be a simple hop skip and jump to some
other bounce proxy or anonomysing web site.

2. Malicious access, again imagine the worst. ARP poisoning, someone
can site at the switch and posion the ARP cache redirecting all LAN
traffic to itself, resolving DNS queries for localized phishing
schemes, DoS (in the form of a rouge DHCP server, tcp RST packets, or
possible exploits on the switch itself.)

3. The list goes on and on.

And don't be pacified into a false sense of security by VLANs they are
very easy enough to defeat in a lab (or WC) environment.

cisco wrote a GREAT white paper on Layer 2 Security

http://www.cisco.com/warp/public/cc/so/cuso/epso/sqfr/sfblu_wp.pdf

What I would do IMMEDIATELY is this:

1. Lock all non used switchports and enable a "sticky" MAC learning
ability for the ones in current use.

2. Read that cisco paper

3. Look into Network Access Control (NAC), even if you don't want to
use it at least be aware of it

4. In the long run it would be ideal, if you can map all known
switchports to known MAC addresses, but if you have a large network
and small staff this may not be possible.

Network Security in my opinion should follow the OSI Layers from most important;

1. Physical - Lock your doors, shred your papers, educate your users
2. Data Link - Lock your local switchports
3. Network - Lock your ports, filter and monitor your traffic, encrypt
inter agency traffic, IDS
4. Transport - filter and monitor your traffic, IDS
5. Session - filter and monitor, use SSH for local admin purposes NOT telnet
6. Presentation - filter out unwanted or unneeded file types from your
LAN traffic and LAN storage
7. Application - Limit user access, patch, patch, patch


Layer 2 is a fertile ground for all manner and methods of attack.

Defend your Layer 2 like you would the door of your office if someone
were trying to break in.


On 14 Nov 2006 09:36:29 -0000, gary.shaw () dfpni gov uk
<gary.shaw () dfpni gov uk> wrote:
> Guys
>
> I am responsible for several LANs that include sharing WCs with other organisations, and therefore access to my 3750 
> switches in unlocked cabinets.
> I have no port security enabled and the ports are not shut down.
> I would like to know the security implications of having unused switchports available to anyone eg with a laptop & DHCP 
> configured?
> Are there any simple pentests i could complete myself?
> Is my organisation's network a sitting duck??
> Thanks in advance!
>
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--
//jkern//timetrap//

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This list is sponsored by: Norwich University

EARN A MASTER OF SCIENCE IN INFORMATION ASSURANCE - ONLINE
The NSA has designated Norwich University a center of Academic Excellence 
in Information Security. Our program offers unparalleled Infosec management 
education and the case study affords you unmatched consulting experience. 
Using interactive e-Learning technology, you can earn this esteemed degree, 
without disrupting your career or home life.

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