RE: Cisco PIX embryonic state machine 1b data DoS



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Cisco Response
==============

This is Cisco PSIRT's response to the statements made by Arhont Ltd.-
Information Security in their messages:
"Cisco PIX embryonic state machine 1b data DoS"
and
"Cisco PIX embryonic state machine TTL(n-1) DoS"
both posted on March 7, 2006.

Attached is a cleartext, PGP signed version of this same email.

The original emails are available at:
http://www.securityfocus.com/archive/1/426989/30/0/threaded
and
http://www.securityfocus.com/archive/1/426991/30/0/threaded

These issues have the same root cause that was documented in Arhont
Ltd.- Information Security's message:
"[Full-disclosure] Cisco PIX TCP Connection Prevention",
posted on November 22, 2005 at:
http://lists.grok.org.uk/pipermail/full-disclosure/2005-November/038971.
html

As detailed in our reply also dated November 22, 2005, this issue is
being tracked by two Cisco Bug ID's:


* CSCsc14915 -- PIX 6.3 Spoofed TCP SYN packets can block
legitimate TCP connections
This Bug ID tracks the issue for PIX software version 6.3 and
older. This DDTS is resolved and available in PIX software
version 6.3(5.106). There are workarounds available to mitigate
the issue.


* CSCsc16014 -- PIX 7.0 Spoofed TCP SYN packets can block
legitimate TCP connections
This Bug ID tracks the issue for PIX/ASA software version 7.0.
This DDTS is resolved and available in PIX/ASA software versions
7.0(4.005) and 7.1(1). Additional mitigations and workarounds
exist to limit or eliminate the issue.


Our November 22, 2005 reply is available at:
http://www.cisco.com/warp/public/707/cisco-response-20051122-pix.shtml

We would like to thank Arhont Ltd.- Information Security for ensuring
that these issues were previously addressed as well.

We greatly appreciate the opportunity to work with researchers on
security vulnerabilities, and welcome the opportunity to review and
assist in product reports.


Additional Information
======================

There have been updates to the information available for these two
Bug ID's since November 22, 2005. The updated Release Note Enclosures
are available at:


CSCsc14915 -- PIX 6.3 Spoofed TCP SYN packets can block legitimate
TCP connections

http://www.cisco.com/pcgi-bin/Support/Bugtool/onebug.pl?bugid=CSCsc14915
(registered customers only:
http://tools.cisco.com/RPF/register/register.do)


CSCsc16014 -- PIX 7.0 Spoofed TCP SYN packets can block legitimate
TCP connections

http://www.cisco.com/pcgi-bin/Support/Bugtool/onebug.pl?bugid=CSCsc16014
(registered customers only:
http://tools.cisco.com/RPF/register/register.do)


Cisco Security Procedures
=========================

Complete information on reporting security vulnerabilities in Cisco
products, obtaining assistance with security incidents, and
registering to receive security information from Cisco, is available
on Cisco's worldwide website at
http://www.cisco.com/en/US/products/products_security_vulnerability_poli
cy.html
This includes instructions for press inquiries regarding Cisco
security notices. All Cisco security advisories are available at
http://www.cisco.com/go/psirt


Regards,
Randy

Randy Ivener
Product Security Incident Response Team (PSIRT)
Cisco Systems, Inc.
rivener@xxxxxxxxx
http://www.cisco.com/go/psirt
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