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RE: wireless security question.
From: "MacFerrin, Ken" <Ken_MacFerrin () csgsystems com>
Date: Thu, 20 Feb 2003 11:38:37 -0600


A company that I previously worked at used WEP 128 with a bi-weekly key update at all their US offices (plus a measure 
of physical security).  The updated key was distributed using an NT authenticated intranet webpage.  This of course was 
backed up with a highly monitored network, strongly enforced security policies, and nearly all internal systems 
requiring additional levels of authentication ranging from NT to PKI once on the network.

To touch on the password thread that's also going on.. This company also enforced a password policy that required an NT 
and voicemail password change every 60 days and used some type of technical tool to enforce strong passwords.  The tool 
required that each password had a minimum length, contained some level of complexity (letters, CAPS, symbols and 
numbers), could not contain any part of the username and could not be significantly similar to a previously used 


-----Original Message-----
From: paul van den bergen [mailto:pvandenbergen () swin edu au]
Sent: Wednesday, February 19, 2003 12:45 AM
To: security-basics () securityfocus com
Subject: wireless security question.

There has been much debate recently in my circle about wireless security, WEP, 
etc. and especially related to the supposed vulnerability of APs to traffic - 
eg. reports that a large % (40%???) do not have WEP enabled. (my arguement is 
that these are likey the smart ones who realise that WEP breaking is routine 
and turn it off as a waste of time...)

as far as I can see, it breaks down like this. You can have wireless sites 
that have WEP off and they cover three basic types

1) Folks who rely on other security measures - IPsec being the most obvious

2) folks who want unrestricted public access - eg. public wireless 
communities, isolated PCs/LANs with no further connectivity. (really a subset 
of 1 I suppose - security not needed because physically isolated, or in some 
other way limited - eg. bandwidth limited)

3) people who have no clue. (and obstrefication is no security at all - SSID 
as security feature? come on!)

with WEP on, I figure that there are 3 classes of sites

4) see three

5) 128 bit WEP on as deterent.  is it worth the effort - low security 
requirements.  somewhat 404 (see 3), but not too bad if you know what you are 

6) 128 WEP + regular key update.  with or without IPsec.

My questions relates to scenario 1 and 6, to me the interesting ones.

In the case of 1) how would one stop external users using the APs as private 
network bridges? 

In the case of 6) how does one distribute the WEP keys at each update?  

Dr Paul van den Bergen
Centre for Advanced Internet Architectures
pvandenbergen () swin edu au
It's a book. Non-volatile storage media. Everyone should have one.

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