[unisog] VPN Protection of Wireless Networks

Harris, Michael C. HarrisMC at health.missouri.edu
Fri Dec 14 14:25:35 GMT 2001


we are side stepping the issue by only allowing Citrix (terminal server)
connectivity to and from the wireless LAN segment and on the wireless
devices. using 128b encryption within both the wireless cards&hub and again
with the Citrix ICA client.  Forcing registration of the mac address at the
wireless hub lets us tightly control our user community.  we believe this is
a must for patient identifiable data and the only we can maintain the spirit
if not the letter of HIPAA.  Application access is also very limited on the
Citrix host to protect against app abuses.

Mike

--------------------------------------------------
Michael C Harris
System Security Analyst - Expert
ITS / Research Education and Support
University of Missouri Health Center
Phone: 573-882-3392 

harrismc at health.missouri.edu
--------------------------------------------------
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-----Original Message-----
From: Patrick Darden [mailto:darden at armc.org]
Sent: Friday, December 14, 2001 7:14 AM
To: Gary Flynn
Cc: unisog at sans.org
Subject: Re: [unisog] VPN Protection of Wireless Networks



You can just use a preshared secret (a password) plus a username.  Make
them both big and varied, e.g.

	username:	robertjordansmith
	password:	bobisHISnameforSURE

The man in the middle attach isn't effective against IPSEC, unless you are
using the lowest possible encryption.  The whole process is encrypted.
Passwords, usernames, etc.

WEP is an attempt at a wireless network with built-in vpn for ease of use
in addition to security. It is a first attempt, and has some severe
problems due to the "ease of use" factor.

--
--Patrick Darden                Internetworking Manager             
--                              706.354.3312    darden at armc.org
--                              Athens Regional Medical Center


On Thu, 13 Dec 2001, Gary Flynn wrote:

> 
> In October I asked about vendor lockins on various security options 
> for wireless networks.  VPN protection was mentioned quite often. 
> >From my reading, effective VPN protection would require each individual 
> user to have a unique key or digital certificate. Are people actually 
> doing that? If so, how are you handling the administration of handing 
> out and revoking keys and certificates? What, if anything is done to 
> educate the end user of the importance of keeping them secret?
> 
> >From a Cisco web page:
> 
> "The wildcard pre-shared key feature is vulnerable to IP spoofing, 
>  specifically the man-in-the-middle attack. An attacker can 
>  potentially redirect all traffic between the IPSec peers to go 
>  through an IKE proxy. If an attacker knows the pre-shared key 
>  and can redirect all traffic between the IPSec peers to go through 
>  an IKE proxy, the attacker can read and modify the IPSec-protected 
>  data without detection."
> 
>
http://www.cisco.com/univercd/cc/td/doc/product/iaabu/csvpnc/csvpnsg/icl3enc
r.htm#29351
> 
> One philosophy I've heard about wireless is not to worry about
> securing it more than your wireless network. However, it sounds to
> me like this type of man-in-the-middle attack is different from
> those against SSH and SSL. With the attacks I've seen against SSH or 
> SSL a user gets a warning message about a changed host key or 
> mismatched certificate. The Cisco doc says the MIM attack against
> IKE can be done without detection.
> 
> Without individual keys or certificates, it would seem to me that
> a wireless network depending upon VPN technology is less secure
> than one depending upon WEP. True?
> 
> thanks,
> -- 
> Gary Flynn
> Security Engineer - Technical Services
> James Madison University
> 
> Please R.U.N.S.A.F.E.
> http://www.jmu.edu/computing/runsafe
> 



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