Security Basics mailing list archives

Re: Nmap Scan Output - PIX firewall shows ports open even when disabled?


From: "erisk" <erisk () iinet net au>
Date: Thu, 30 Oct 2003 14:24:59 +0800

Yes there is a cisco border router (12.x) in front of it PIX is a 6.2(x)
version...

Scanning this router there is still the same ports open, which is wierd
becuase it is more upstream then the PIX...

Telneting to them opens a connection as well... And your right internal
scans only show what "should" be open...

Thoughts? Although the nmap version wont fix anything or change the results
becasue you can still make a manul connection.

----- Original Message ----- 
From: "Dan Duplito" <danduplito () techie com>
To: <security-basics () securityfocus com>
Sent: Wednesday, October 29, 2003 9:52 AM
Subject: Re: Nmap Scan Output - PIX firewall shows ports open even when
disabled?



were you scanning PIX directly from an L2 switch or from behind a router?
with the latter, i get a similar output when scanning a target system
(protected by PIX) behind a (Cisco) router that i believe was configured
weirdly. the scan show the exact same open ports for all systems behind that
"funny" router, in addition to the open ports of the target system.

i get the "expected" scan results of the system when i internally scan PIX
directly.

regards,
dan

PS

i recommend you upgrade/recompile your nmap version to the latest V3.48 -- 
the database is much more extensive and Fyodor finally incorporated "service
scanning" feature (which i used to get only from THC's amap scanner).


erisk wrote:
Hi all,

I have had this on a few instances and I was wondring if anyone can
verify
if this is something other people have found when scanning PIX's or
web
servers in the DMZ..

Firstly I scanned using the normal sS routine and ports were found
closed.
Following that I preceded to scan without pinging the host and the
output is
below:

nmap -P0 XXX.XXX.XXX.XX

Starting nmap V. 3.00 ( www.insecure.org/nmap/ )
Interesting ports on XXXX (X.X.X.X):
(The 1596 ports scanned but not shown below are in state: filtered)
Port       State       Service
389/tcp    open        ldap
1002/tcp   open        unknown
1720/tcp   open        H.323/Q.931

I have confirmed with the rulebase and the none of the ports that are
open
are defined in the rule base and everything elese is still explictly
denied
(even though PIX does it by default) by a deny IP rule. Also the
majority of
fixup protocols have been disbaled (except HTTP, SMTP).

Also when I scan web servers behind the firewall with this option it
still
has the same ports open + HTTP and HTTPS...

This is the third time I have had this output when using this no ping
host
option, so has anyone found the similar outputs? Could this be a
common way
to commonly identify PIX firewalls? Is there an advisory for this? And
are
there any workarounds so these ports are not shown on the no ping
scan?

Regards,
Trev

-- 
Francisco Andrades Grassi
www.nextj.com
Tlf: +58-414-125-7415



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---------------------------------------------------------------------------
Forum Systems PRESIDIO: PGP / XML GATEWAY APPLIANCE
The Presidio integrates PGP data encryption and XML Web Services security to 
simplify the management and deployment of PGP and reduce overall PGP costs 
by up to 80%.
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