[tcpm] I-D Action:draft-ietf-tcpm-tcpsecure-12.txt

Internet-Drafts@ietf.org Mon, 14 September 2009 15:30 UTC

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Subject: [tcpm] I-D Action:draft-ietf-tcpm-tcpsecure-12.txt
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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)       : A. Ramaiah, et al.
	Filename        : draft-ietf-tcpm-tcpsecure-12.txt
	Pages           : 26
	Date            : 2009-09-14

TCP has historically been considered protected against spoofed off-
path 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 longer term connections (e.g.  H-323 or
Border Gateway Protocol [RFC4271]) have left modern TCP
implementations more vulnerable to these types of spoofed packet
injection attacks.

Many of these long term TCP applications tend to have predictable IP
addresses and ports which makes it far easier for the 4-tuple
(4-tuple is the same as the socket pair mentioned in [RFC0793]) to be
guessed.  Having guessed the 4-tuple correctly, an attacker can
inject a TCP segment with the RST bit set, the SYN bit set or data
into a TCP connection by systematically guessing the sequence number
of the spoofed segment to be in the current receive window.  This can
cause the connection to abort or cause data corruption.  This
document specifies small modifications to the way TCP handles inbound
segments that can reduce the chances of a successful attack.

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