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Re: Cisco CSS 11000 Series DoS
From: Mike Caudill <mcaudill () cisco com>
Date: Sun, 7 Sep 2003 18:13:08 -0400


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Hello S21Sec,

Apologies for our delay in response, but we have been thoroughly testing 
and investigating this issue to ensure our response is accurate.

Normally, it is not our policy to comment on customer cases, however, since 
this has been posted as a Security Advisory that contains inaccurate 
information, we must respond with the correct details.

It appears that the original customer case was possibly misdiagnosed, 
leading to the incorrect information in your advisory.  Hence the details 
on the mechanics of this attack are incorrect.  We will only correct the 
defect identifier, upgrade information, affected platform information and 
workaround details here.

The upgrade listed in the solution section of the advisory will not provide 
a solution to the problem stated in your advisory.  We have been able to 
reproduce a reload given the instructions in your advisory ONLY on the 
11800 platform with a heavy storm of TCP SYN packets sent to the circuit 
address of the CSS.  This problem has been documented in CSCec01994.  We 
are working on delivering a fix for the specific problem (CSCec01994) into 
the next 5.0 and 6.10 maintenance releases which will be available shortly, 
possibly by the end of the month.

This problem is seen on the 5.0.2.03 and 6.10 Build 4 versions and is 
specific to the 11800 platform.  It does *not* affect the 11150 and 11050 
platforms.

Using ACLs on an upstream router to protect the circuit address is 
recommended as a prevention measure, or workaround.  For example, the command

access-list 116 deny tcp any <circuit address of CSS>

can be used on an upstream router in combination with applying the 
access-group to an outgoing interface to deny TCP to circuit addresses on 
the CSS.

Thanks much for posting this information, although working with the Cisco 
PSIRT in the future on advisories will eliminate this type of confusion and 
inaccurate information.

We do greatly appreciate the opportunity to work with researchers on 
security vulnerabilities, and welcome the opportunity to review and assist 
with Product Security Advisories.  Our ultimate goal is to ensure that 
customers have accurate information on which to base upgrade and workaround 
decisions and we welcome partnership with researchers towards that goal.

Thanks,

- -Mike-


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S21SEC <vul-serv () s21seccom s21sec com> [2003-08-07 18:30] wrote:
###############################################################
ID: S21SEC-025-en
Title: Cisco CSS 11000 Series DoS
Date: 04/07/2003
Status: Solution available
Scope: Interruption of service, high CPU load.
Platforms: All/Chassis CS800.
Author: ecruz, egarcia, jandre
Location: http://www.s21sec.com/en/avisos/s21sec-025-en.txt
Release: External
###############################################################

                              S 2 1 S E C

                         http://www.s21sec.com

                   Cisco CSS 11000 Series Denial of service



Description of vulnerability
----------------------------

A heavy storm of TCP SYN packets directed to the circuit address of the 
CSS 
can cause DoS on it, high cpu load or even sudden reboots.

The issue is known by cisco as the ONDM Ping failure (CSCdz00787). On the 
CS800 chassis the
system controller module (SCM) sends ONDM (online diagnostics monitor) 
pings to each SFP card
in order to see if they are alive, if the SCM doesn't get a response in 
about 30 seconds the
SCM will reboot the CS800 and there will be no core.

By attacking the circuit IP address of the CSS with SYN packets the 
traffic is sent up to the SCM
over the internal MADLAN ethernet interface. If this internal interface 
becomes overloaded
the ONDM ping request and response traffic can be dropped leading this to 
an internal DoS
since no internal comunications are available.

Any attacker could do this externally with a few sessions of NMAP and a 
cable/ADSL internet
connection.


Affected Versions and platforms
-------------------------------

This vulnerability affects the models 11800, 11150 and 11050 with chassis 
CS800.


Solution
--------

Upgrade to software release WebNS 5.00.110s or above.
http://www.cisco.com/en/US/products/hw/contnetw/ps789/prod_release_note0918
6a008014ee04.html

AcL's to protect the circuit address are recomended.


Additional information
----------------------

These vulnerabilities have been found and researched by:

 Eduardo Cruz            ecruz () s21sec com
 Emilin Garcia                 egarcia () s21sec com
 Jordi Andre            jandre () s21sec com

You can find the last version of this warning in:

        http://www.s21sec.com/en/avisos/s21sec-025-en.txt

And other S21SEC warnings in http://www.s21sec.com/en/avisos/

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-- 
----------------------------------------------------------------------------
|      ||        ||       | Mike Caudill           | mcaudill () cisco com    |
|      ||        ||       | PSIRT Incident Manager | +1.919.392.2855       |
|     ||||      ||||      | DSS PGP: 0xEBBD5271    | +1.919.522.4931 (cell)|
| ..:||||||:..:||||||:..  | RSA PGP: 0xF482F607    ------------------------|
| C i s c o S y s t e m s | http://www.cisco.com/go/psirt                  |
----------------------------------------------------------------------------


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