[tcpm] I-D ACTION:draft-ietf-tcpm-tcpsecure-04.txt

A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the TCP Maintenance and Minor Extensions Working Group of the IETF.

	Title		: Improving TCP's Robustness to Blind In-Window Attacks
	Author(s)	: R. Stewart, M. Dalal
	Filename	: draft-ietf-tcpm-tcpsecure-04.txt
	Pages		: 27
	Date		: 2006-2-15

A recent study indicates that some types of TCP connections have an
   increased vulnerability to spoofed packet injection attacks than
   previously believed [SITW].  TCP has historically been considered
   protected against spoofed packet injection attacks by relying on the
   fact that it is difficult to guess the 4-tuple (the source and
   destination IP addresses and the source and destination ports) in
   combination with the 32 bit sequence number(s).  A combination of
   increasing window sizes and applications using a longer term
   connections (e.g.  H-323 or Border Gateway Protocol [RFC1771]) have
   left modern TCP implementation more vulnerable to these types of
   spoofed packet injection attacks.

   Note: Both [SITW] and [DTASA] provide charts which can give the
   reader an idea as to the time it takes to penetrate an unprotected
   system.

   Many of these long term TCP applications tend to have predictable IP
   addresses and ports which makes it far easier for the 4-tuple to be
   guessed.  Having guessed the 4-tuple correctly, an attacker can
   inject a RST, SYN or DATA segment into a TCP connection by carefly
   crafting the sequence number of the spoofed segment to be in the
   current receive window.  This can cause the connection to either
   abort or possibly cause data corruption.  This document proposes
   small modifications to the way TCP handles inbound segments that can
   reduce the probability of such an attack.

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