RE: Dsniff'ng wireless networks

From: R. DuFresne (dufresneat_private)
Date: Thu Jul 12 2001 - 16:08:15 PDT

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    Yes, still, how many of those improvements are currently in use?
    
    
    Thanks,
    
    Ron DuFresne
    
    On Thu, 12 Jul 2001, Kohlenberg, Toby wrote:
    
    > If you haven't done so yet, take a look at the revisions
    > made for the next release of 802.11- specifically 802.11i
    > a number of interesting improvements in the standard with
    > regard to security. It has been significantly developed by
    > Jesse Walker who is definately competent.
    > 
    > Toby
    > 
    > > -----Original Message-----
    > > From: Dragos Ruiu [mailto:drat_private]
    > > Sent: Wednesday, July 11, 2001 5:48 PM
    > > To: Michael H. Warfield; Bourque Daniel
    > > Cc: pen-testat_private
    > > Subject: Re: Dsniff'ng wireless networks
    > > 
    > > 
    > > IMHO the Cisco 350 (not the weaker gain cousin the 340) 
    > > is _the_ card  to get.... if for no other reason than you can 
    > > crank that  transmitter to a rangeful but unhealthy and 
    > > battery frying  three times the normal power rating of 
    > > other typical  cards (30mW vs. 100mW) or right down to 
    > > a less  unhealthy and battery saving 1mW with the 
    > > OpenBSD  drivers (and it works fine for me in an indoor 
    > > residential  setting at this minimal power level).  As 
    > > far as I have tested none of the other cards/chipsets give 
    > > you any useful power controls beyond the mostly lame 
    > > keep the transmitter on for so many milliseconds  
    > > settings which mostly mess up your link without 
    > > much savings. Never mind the fact that you can 
    > > also use this card to break the shamefully bad crypto. :-)
    > > "Who forgot to invite the cryptographers?", indeed.
    > > 
    > > cheers,
    > > --dr
    > > 
    > > 
    > > 
    > > On Tue, 10 Jul 2001, Michael H. Warfield wrote:
    > > > On Tue, Jul 10, 2001 at 11:04:34AM -0400, Bourque Daniel wrote:
    > > > 
    > > > > What about the claim by Cisco that the 350 couple with 
    > > their Cisco Secure
    > > > > Access Control permit to each user to have it's own key 
    > > AND dynamic change
    > > > > of thoses keys?
    > > > 
    > > > 	It's proprietary software on top of their cards.  I'm still
    > > > waiting to see the software in action AND waiting to see 
    > > Linux support.
    > > > Till then, it's still vaporware.  IAC, it's certainly NOT 
    > > what you are
    > > > going to find deployed in the field at this time.
    > > > 
    > > > 	There is also the SLAN project up at SourceForge with 
    > > is intended
    > > > to address the Wireless encryption problem.  That has Linux 
    > > and Windows
    > > > clients and is also suppose to address this, and not just be limited
    > > > to Cisco cards.
    > > > 
    > > > > -----Message d'origine-----
    > > > > De: Michael H. Warfield [mailto:mhwat_private]
    > > > > Date: 9 juillet, 2001 21:08
    > > > > À: ed.rolisonat_private
    > > > > Cc: pen-testat_private
    > > > > Objet: Re: Dsniff'ng wireless networks
    > > > > 
    > > > > 
    > > > > On Mon, Jul 09, 2001 at 09:09:58AM +0100, 
    > > ed.rolisonat_private wrote:
    > > > > 
    > > > > > Correct me if I'm wrong, but IIRC wireless lans are 
    > > effectively switched.
    > > > > 
    > > > > 	You are wrong...  They are broadcast media and one station can
    > > > > sniff another station as long as it can receive the RF.  
    > > Often, one
    > > > > station might not be able to receive another stations RF 
    > > because they
    > > > > are out of range of each other but not out of range of 
    > > the high-gain
    > > > > access point antenna.  But that is a far cry from 
    > > "effectively switched"
    > > > > and is NOT something to rely on for security!
    > > > > 
    > > > > > Each access point-NIC uses a separate encryption key 
    > > (there are weaknesses
    > > > > > but...)
    > > > > 
    > > > > 	You are VERY wrong.  WEP uses a common shared key amongst ALL
    > > > > of the stations.  In order to move between access points within a
    > > > > fully managed 802.11 network (multiple access points operating
    > > > > in cooperation) then all the access points have to have the same
    > > > > Network Name and WEP encryption keys.  Most seem to 
    > > support 4 decryption
    > > > > keys (Rx) and a single encryption key (Tx - One of the 
    > > four Rx keys)
    > > > > but to have everything work uniformly, it would all have 
    > > to be identical
    > > > > and it's ALL shared secrets.
    > > > > 
    > > > > > and thus the NIC only 'sees' traffic being directed at it.
    > > > > 
    > > > > 	If that were true, then the WaveLAN sniffers would not be
    > > > > very effective.  In fact, they are VERY effective.
    > > > > 
    > > > > > It seems also that it's quite hard to get them to enter 
    > > promiscuous mode
    > > > > for
    > > > > > similar reasons - if
    > > > > > it's listening to all the traffic, then the encryption 
    > > breaks down.
    > > > > 
    > > > > 	1) It's a snap to get it into promiscuous mode.  Tcpdump can do
    > > > > it on Linux, no mods necessary.  You see 802.3 (ethernet) 
    > > style frames
    > > > > and encapsulation.  The 802.11 framing is stripped before 
    > > presentation
    > > > > to the application layer.
    > > > > 
    > > > > 	2) It's a little more difficult to get it into RF 
    > > Management/Monitor
    > > > > mode.  In fact, we don't know how to get some cards 
    > > (Lucent, Cabletron, etc)
    > > > > into this mode where we can monitor access point 
    > > management frames.  Other
    > > > > cards (Cisco Aironet 340 and 350) go into RF 
    > > Management/Monitor mode very
    > > > > readily.  I have several.  I've seen them in action.  :-) 
    > >  I prefer the
    > > > > 350.  Better receive gain.  Picks up much better than the 
    > > 340.  Also has
    > > > > better transmit power (but I'm not usually transmitting :-) ).
    > > > > 
    > > > > 	3) On Linux, some driver patches are required to report 
    > > the ENTIRE
    > > > > 802.11 encapsulation to the application layer and then 
    > > you need some
    > > > > modified
    > > > > libpcap libraries to handle them (they are different 
    > > sized than 802.3).
    > > > > Once you have that, you can find out the ESSID, the 
    > > Network Name, various
    > > > > AP parameters (like whether WEP is required or used), 
    > > etc, etc, etc...
    > > > > 
    > > > > 	Driving from home to work along a particular route, I 
    > > know a dude
    > > > > in a certain apartment complex has "Dougnet" while a 
    > > medical office further
    > > > > down the road has one named "toomanysecrets".  It's 
    > > amazing how many
    > > > > have purchased a particular brand with a particular 
    > > default network name
    > > > > and I see "tsunami" showing up all over the map while 
    > > driving around town.
    > > > > 
    > > > > > You might have some joy, but the best I can see for 
    > > collecting the
    > > > > datagrams
    > > > > > would be something like
    > > > > > a scanner (radio) interfaced to a computer. Of course, 
    > > you still have to
    > > > > break
    > > > > > the encryption, but there
    > > > > > was an article posted to one of the securityfocus lists 
    > > regarding
    > > > > 'weaknesses'
    > > > > > in WEP.
    > > > > 
    > > > > 	Yes, there certainly are some "weaknesses" in WEP.  You 
    > > might want
    > > > > to look them over.  They're incredibly lame, like reusing 
    > > the undersized
    > > > > (24 bit) IV and NOT encorporating any station dependent 
    > > information in
    > > > > the IV or cypherstream (so cracking one station using 
    > > known plaintext
    > > > > cracks them all).  Combined that with a simple XOR 
    > > between the plaintext
    > > > > and the cypherstream (making is subject to XOR reduction 
    > > attacks) it's
    > > > > really pretty bad.  "Bag on head" bad...  "Go home in 
    > > shame" bad...
    > > > > "Who forgot to invite the cryptographers to the meetings" bad...
    > > > > 
    > > > > > (this is based on a little research I did into 802.11b YMMV)
    > > > > 
    > > > > > Cheers
    > > > > > Ed
    > > > > 
    > > > > > CONFIDENTIALITY:
    > > > > > This e-mail and any attachments are confidential and 
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    > > > > you
    > > > > > are not a named recipient, please notify the sender 
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    > > > > > disclose the contents to another person, use it for any 
    > > purpose, or store
    > > > > or
    > > > > > copy the information in any medium.
    > > > > 
    > > > > 	Mike
    > > > > -- 
    > > > >  Michael H. Warfield    |  (770) 985-6132   |  mhwat_private
    > > > >   (The Mad Wizard)      |  (678) 463-0932   |  
    > http://www.wittsend.com/mhw/
    > > >   NIC whois:  MHW9      |  An optimist believes we live in the best of
    > all
    > > >  PGP Key: 0xDF1DD471    |  possible worlds.  A pessimist is sure of it!
    > > 
    > > 	Mike
    > > -- 
    > >  Michael H. Warfield    |  (770) 985-6132   |  mhwat_private
    > >   (The Mad Wizard)      |  (678) 463-0932   |
    > http://www.wittsend.com/mhw/
    > >   NIC whois:  MHW9      |  An optimist believes we live in the best of all
    > >  PGP Key: 0xDF1DD471    |  possible worlds.  A pessimist is sure of it!
    > > 
    > > 
    > >
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