RE: OT: the detection of illegal gateways

["Ward, Jon" <Jon_Ward () syntelinc com>]

I like the traffic analysis idea mentioned below.  It's not enough to
conclusively determine that there is no additional connection there, but
it could certainly give you some places to begin investigation.

If it were me, I'd start with gathering complete network inventory
information.  It's easily attainable and once you have a complete
inventory, you can analyze the information in many different ways.  A
complete inventory is great launch pad for additional information
gathering.

1.) Get the MAC address of each node on the network.  The first half of
each MAC address is vendor specific.  These could give you clues.  If
you see a Cisco NIC, for example, where you know that your organization
uses 3Com NICs in your systems, that might be a good place to look.  If
you can connect to each of your organization's switches, these will
readily available, and reliable.  If it's not in your switch's MAC
table, it's probably not getting any frames.  Perhaps a quick shell
script to loop through an IP address range and ARP each would give you
what you need.  Keep in mind that you'll need to launch the arp command
from a node on the target subnet.  If not, everything will point to your
next hop router.  If you're in a windows environment, try nbtstat.

2.) nmap has some features that could help.  The standard "nmap -sS -v
-O 172.16.0.0/16" CL will give you lots of info to weed out the majority
of PCs, servers and printers.   Maybe use -PO to scan for IP addresses
that have certain protocols enabled that most hosts do not
(http://nmap.org/svn/nmap-protocols).  Check out other capabilities that
could point out differences between hosts.

3.) Remember that almost any host on a network could have routing
capability, so don't eliminate them as possible offenders too early.
The connection that you seek may be on the other side of a windows or
*nix machine.  It may prove beneficial to retrieve the routing table
from each host.  (eg: "ROUTE PRINT" at a windows CL will show the
interfaces and routes for that host)

4.) If these pathways are being established covertly, they may be more
difficult to detect as they may not be physical devices or connections.
It is pretty easy to set up an encrypted tunnel through a proxy server
and firewall and use a virtual interface that routes through this
tunnel.  You could retrieve processes from each host and examine/scan
each list.  It might be easier to generate a packet that will be routed
to an internet IP (send spoofed packets to every internal host that will
be responded to via the internet).

My suggestion is to gather as much information as possible and let your
analytic creativity run wild.

Don't forget to consider your goal in finding these gateways, because
the amount you can spend on this defense is limited by what/how much
your organization could potentially lose.  Are you trying to manage
traffic and network costs?  Are you trying to eliminate paths for bad
guys to get in?  Are you trying to eliminate paths for information to
get out unchecked?  Trying to keep employees from looking at porn?  The
implication is that some methods are easier than others, and some are
more thorough and effective.  Some are more expensive and
time-consuming.  How far do you want to go?  How much is it worth to
you?





Jon Ward, CEPT, CISA
Vulnerability Testing Technical Lead
Syntel, Inc.
Jon_Ward () syntelinc com
Cell: (773) 680-8090
Office: (901) 748-3625
 





-----Original Message-----
From: listbounce () securityfocus com [mailto:listbounce () securityfocus com]
On Behalf Of Lee
Sent: Saturday, May 22, 2010 9:43 AM
To: J Hein
Cc: pen-test () securityfocus com
Subject: Re: OT: the detection of illegal gateways

There's been a lot of good suggestions for finding 'illegal' routers.
The two I like the best are:
> 5) talk with purchasing dept and give them 'keywords' that they can
use to
> look through purchases to see where an internet connection may have
been
> purchased with a corporate credit card
>   ...
> 7) if all internet traffic is supposed to pass through an internet
firewall
> or proxy, look for "lack of traffic" from IP blocks on your WAN.  Even
a
> regular windows machine sitting at rest is sending out queries to
windows
> update, NTP, DNS, etc.

What I haven't seen mentioned yet is using Netflow to report on layer 2
traffic.

If you're ok with writing your own software & the customer has the
right hardware you could try modifying he cisco TCL Portscanner
(http://www.packetlevel.ch/html/cisco/ciscotcl.html) to loop thru all
addresses on the user subnet doing a
  ip route $internetWebServer 255.255.255.255 $host
  connect $internetWebServer 80
  no ip route $internetWebServer 255.255.255.255 $host
to find the 'illegal' routers.

Regards,
Lee


On 5/17/10, J Hein <j.hein () ymail com> wrote:
> hi all,
> this post might be somewhat off-topic, so please accept my apologies
first.
> I have a somewhat difficult problem to crack - there is a large
corporate
> network which covers several Nordic countries, and unfortunately there
have
> been cases in the past where a device with routing capability has been
> plugged into the network (for creating a "faster" connection to the
internet
> for a branch office). Because this violates corporate policies and
creates
> "invisible" entry points to the internal network, I have been given a
task
> to find a suitable software for finding such kind of illegal routers.
>
> Are there any good products for detecting illegally installed boxes
with a
> routing capability? One of my fellow consultants suggested IP Sonar
(by
> Lumeta) for this purpose which (as he claims) has been successfully
used by
> BT in the past. From the product description I've got an impression
that IP
> Sonar cleverly uses traceroute for detecting routers that illegally
exchange
> information between internal networks and the internet (so called
"network
> leaks").
>
> I understand that router detection is a complex issue, and in order to
> address this problem fully, one needs to analyze traffic that flows
through
> all key routers and switches in the whole corporate network.
Unfortunately,
> since the deployment of such monitoring system takes a lot of time,
I'd like
> to begin with a relatively simple solution which attempts to locate
network
> leaks by polling the network from few points only (like IP Sonar does,
using
> traceroute for that purpose).
>
> Can anyone recommend any such commercial or open source tools? (open
source
> utilities would actually be my preference :)  Also, what is your
experience
> with IP Sonar -- is it really a good stuff?
>
> Thanks in advance :)
> --
> jhein
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This list is sponsored by: Information Assurance Certification Review
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Prove to peers and potential employers without a doubt that you can
actually do a proper penetration test. IACRB CPT and CEPT certs require
a full practical examination in order to become certified. 

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This list is sponsored by: Information Assurance Certification Review Board

Prove to peers and potential employers without a doubt that you can actually do a proper penetration test. IACRB CPT 
and CEPT certs require a full practical examination in order to become certified.

http://www.iacertification.org
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