Full Disclosure mailing list archives
Re: NAT router inbound network traffic subversion
From: Bart.Lansing () kohls com
Date: Fri, 28 Jan 2005 12:48:15 -0600
Actually...if you bothered to read the whole work, and did not just skim it, you would see that the team at Columbia very specificially states that their analytic techniques can be easily confused, and that there are basic steps for NAT use/configuration that render their techniques basically useless. Also, as intranet traffic fogs their results considerably, they state that this technique is not at all valid where such traffic occurs. There are more caveats, such as proximity to the source NAT device, etc...as well as the process missing multiple machines...in the paper, but enough...you get my point. No offense, but their work does not say what you said it says. Bart Lansing Manager, Desktop Services/Lotus Notes Kohl's IT full-disclosure-bounces () lists netsys com wrote on 01/28/2005 10:26:40 AM:
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Check it here -> http://www1.cs.columbia.edu/~smb/papers/fnat.pdf This should help clarify why NAT can not be considered a security feature. On Thu, 27 Jan 2005 22:12:19 -0800 Kristian Hermansen <khermansen () ht-technology com> wrote:I have Googled around and asked a highly-respected Professor at my University whether it is possible to direct packets behind a NAT router without the internal 192.168.x.x clients first requesting a connection to the specific host outside. The answer I received is "not possible". I also asked if this can be thought of as a security feature, to which the reply was again "yes". Now, I wouldn't place all my bets on his answer and I am calling on someone out there to clear up my question. If NAT really does only allow inbound connections with a preliminary request as he suggests, it seems that the only way to get an "unauthorized" packet behind the router is by some flaw in the firmware of the device. How about if the client has requested a connection to Google.com from behind his Linksys home NAT router: would it be possible for an outside attacker to spoof packets from Google's IP to get packets into the network? Or do we need to know the sequence numbers as well? Or is there an even more devious way to get packets on the inside without a client's initiative? Has there been any research into this? Are there statistics on worm propagation and exploited network hosts in relation to those individuals that did not own routers (and instead connected directly to their modem)? If *all* home users on the Internet had NAT routers during the summer of 2003, would we have significantly slowed the spread of Blaster? I believe these all to be very important questions and the security aspects of the ability to route packets behind NAT really interests me...maybe some of you can elaborate :-) -- Kristian Hermansen <khermansen () ht-technology com>-----BEGIN PGP SIGNATURE----- Note: This signature can be verified at https://www.hushtools.com/verify Version: Hush 2.4 wkYEARECAAYFAkH6Z/UACgkQ1kZ6e0Djf6zn3wCgiIb4yUWKP82hge9Oml7Qp75lOR0A oK4bjNPHtARambOFA4IallqA/b8C =Z8vB -----END PGP SIGNATURE----- Concerned about your privacy? Follow this link to get secure FREE email: http://www.hushmail.com/?l=2 Free, ultra-private instant messaging with Hush Messenger http://www.hushmail.com/services-messenger?l=434 Promote security and make money with the Hushmail Affiliate Program: http://www.hushmail.com/about-affiliate?l=427 _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.netsys.com/full-disclosure-charter.html
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Current thread:
- NAT router inbound network traffic subversion Kristian Hermansen (Jan 28)
- Re: NAT router inbound network traffic subversion morning_wood (Jan 28)
- Re: NAT router inbound network traffic subversion Joe (Jan 28)
- Re: NAT router inbound network traffic subversion Darren Bounds (Jan 28)
- <Possible follow-ups>
- Re: NAT router inbound network traffic subversion Kristian Hermansen (Jan 28)
- Re: NAT router inbound network traffic subversion bart2k (Jan 28)
- Re: NAT router inbound network traffic subversion Bart . Lansing (Jan 28)
- RE: NAT router inbound network traffic subversion Mark Senior (Jan 28)
- Re: NAT router inbound network traffic subversion raize (Jan 28)