RE: VPN's - Firewall's and Security

["Christopher Joles" <CJoles () proteabhs com>]

Here is what we did to solve our delima

On the PIX we had an access list associated with the outside interface,
we turned off sysopt connection permit ipsec and then added the
following to the outside access-list:

access-list 102 permit tcp 192.168.18.0 255.255.255.0 192.168.0.0
255.255.255.0 eq smtp 
access-list 102 permit tcp 192.168.18.0 255.255.255.0 192.168.0.0
255.255.255.0 eq pop3 
access-list 102 permit tcp 192.168.18.0 255.255.255.0 192.168.0.0
255.255.255.0 eq 3389 
access-list 102 permit tcp 192.168.18.0 255.255.255.0 192.168.0.0
255.255.255.0 eq www 
access-list 102 permit tcp 192.168.18.0 255.255.255.0 192.168.254.0
255.255.255.0 eq www 
access-list 102 permit tcp 192.168.18.0 255.255.255.0 192.168.254.0
255.255.255.0 eq 3389 
access-list 102 permit tcp 192.168.18.0 255.255.255.0 192.168.254.0
255.255.255.0 eq pop3 
access-list 102 permit tcp 192.168.18.0 255.255.255.0 192.168.254.0
255.255.255.0 eq smtp 
access-list 102 permit ip 192.168.18.0 255.255.255.0 host 192.168.0.222 

My original goal was to only allow ports 3389, 25, 110, and 80 over the
VPN connections.  What you see above does exactly that, along with the
last line allowing dns and wins too.

Reading through the access list, 192.168.18.x is the subnet assigned to
any outside VPN connection, 192.168.0.x is the private network and
192.168.254.x is the DMZ nework.

I'd like to thank everyone for their help and assistance.



Christopher J. Joles
Chief Information Officer


-----Original Message-----
From: HOULE, FRANCIS [mailto:francis.houle () bell ca] 
Sent: Wednesday, September 03, 2003 1:06 PM
To: 'Shota Gedenidze'; Christopher Joles;
security-basics () securityfocus com
Subject: RE: VPN's - Firewall's and Security


You cannot use map [mapname] match address [access-list name] for VPN
clients.  Only for static crypto maps...

VPN clients uses dynamic crypto map and you cannot match traffic through
access-list in those crypto's!!!!

Like I said, and this is confirmed by multiple SE's at cisco's, the only
way to filter traffic from vpn clients is with X-auth...

--
Francis Houle
(514) 870-0388


-----Original Message-----
From: Shota Gedenidze [mailto:security () tub ge] 
Sent: Wednesday, August 27, 2003 2:53 AM
To: 'Christopher Joles'; security-basics () securityfocus com
Subject: RE: VPN's - Firewall's and Security


Hi there,

Since you have vpn it is not firewalled!

You had configured that vpn users access internal network, You need to
modify your PIX Config, you have configured "crypto map [mapname] match
address [access-list name]"

You should modify that access-list and prohibit there following traffic:

Tcp/udp 135, 137, 139, 445

These ports are commonly used by rpc service.

Also block tftp protocol , tcp port 4444- this port is opened by
blaster.


My advise:

Block everything and then allow ONLY important protocols you use.

In access-lists use permit tcp, permit udp, permit icmp rather than
permit ip which is less specific.


Sincerely,
Shota Gedenidze.


-----Original Message-----
From: Christopher Joles [mailto:CJoles () proteabhs com] 
Sent: Tuesday, August 26, 2003 7:09 PM
To: security-basics () securityfocus com
Subject: VPN's - Firewall's and Security

Good Day All!

I'm looking for design advice.

Currently, I have a network that is protected by a Cisco PIX 515 =
firewall.  We have it configured to protect our internal network along =
with supplying access to our DMZ which holds our email and web servers.

My concern arises from the spread of the blaster worm.  Currently we =
give a couple employees (the boss, the CFO and myself) VPN access from =
home.  In this scenario, the bosses home computer was compromised by the
= blaster worm and luckily for me, he was on vacation in Germany at the
= time.  If he wasn't, he most assuridly would have made a VPN
connection = and the lovely blaster worm would have gotten through our
defenses.  = Keep in mind, I had applied the MS patch to our servers and
= workstations, however, it would have still gotten "inside".  How can I
= redesign my network to either firewall the VPN connections or at a =
minimum filter them.

Thanx for your opinions in advance!

Christopher J. Joles
Chief Information Officer

PROTEA Behavioral Health Services
187 Exchange St.
Bangor, ME 04401
Phone: (207)992-7010 Ext: 245  Fax:(207)992-7011



------------------------------------------------------------------------
---
Attend Black Hat Briefings & Training Federal, September 29-30
(Training), 
October 1-2 (Briefings) in Tysons Corner, VA; the world's premier 
technical IT security event.  Modeled after the famous Black Hat event
in 
Las Vegas! 6 tracks, 12 training sessions, top speakers and sponsors.  
Symantec is the Diamond sponsor.  Early-bird registration ends September
6.Visit us: www.blackhat.com
------------------------------------------------------------------------
----


------------------------------------------------------------------------
---
Attend Black Hat Briefings & Training Federal, September 29-30
(Training), 
October 1-2 (Briefings) in Tysons Corner, VA; the world's premier 
technical IT security event.  Modeled after the famous Black Hat event
in 
Las Vegas! 6 tracks, 12 training sessions, top speakers and sponsors.  
Symantec is the Diamond sponsor.  Early-bird registration ends September
6.Visit us: www.blackhat.com
------------------------------------------------------------------------
----






------------------------------------------------------------------------
---
Attend Black Hat Briefings & Training Federal, September 29-30
(Training), 
October 1-2 (Briefings) in Tysons Corner, VA; the world's premier 
technical IT security event.  Modeled after the famous Black Hat event
in 
Las Vegas! 6 tracks, 12 training sessions, top speakers and sponsors.  
Symantec is the Diamond sponsor.  Early-bird registration ends September
6.Visit us: www.blackhat.com
------------------------------------------------------------------------
----


---------------------------------------------------------------------------
Captus Networks
Are you prepared for the next Sobig & Blaster?
 - Instantly Stop DoS/DDoS Attacks, Worms & Port Scans
 - Precisely Define and Implement Network Security
 - Automatically Control P2P, IM and Spam Traffic
FIND OUT NOW -  FREE Vulnerability Assessment Toolkit
http://www.captusnetworks.com/ads/42.htm
----------------------------------------------------------------------------