[NEWS] Cisco ONS15454 IP TOS Bit Vulnerability

From: support@securiteam.com
Date: 06/21/02 

From: support@securiteam.com
To: list@securiteam.com
Date: Fri, 21 Jun 2002 21:50:25 +0200 (CEST)

The following security advisory is sent to the securiteam mailing list, and can be found at the SecuriTeam web site: http://www.securiteam.com
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  Cisco ONS15454 IP TOS Bit Vulnerability
------------------------------------------------------------------------

SUMMARY

The Cisco ONS15454 optical transport platform is vulnerable when IP
packets, with the Type Of Service (TOS) bit set, are sent to the Timing
Control Card (TCC) LAN interface. Cisco ONS software releases 3.1.0 to
3.2.0, both inclusive, are vulnerable.

This vulnerability is documented as Cisco bug ID CSCdx48853. There are
workarounds available to mitigate the effects of this vulnerability.

DETAILS

Affected Products:
All Cisco ONS15454 hardware running Cisco ONS release 3.1.0 to 3.2.0, both
inclusive, is affected by this vulnerability.

Hardware not affected includes the Cisco ONS15327 edge optical transport
platform, Cisco ONS15540 extended service platform, ONS15800 series,
ONS15200 series metro DWDM systems and the ONS15194 IP transport
concentrator.

No other Cisco product is currently known to be affected by this
vulnerability.

To determine your software revision, view the help-about window on the
CTC.

Details:
When an IP packet with non-zero TOS bits in its header is received by the
TCC on its LAN interface, this causes software versions 3.1.0 and later to
reset the TCC. When the crafted packets are sent repeatedly, both TCCs
reset leaving no active TCC in the platform.

In order to exploit this vulnerability, an attacker must be able to
establish an IP connection to the TCC's LAN interface.

This vulnerability is documented as Cisco bug ID CSCdx48853, which
requires a CCO account to view, and can be viewed after 2002 June 20 at
1500 UTC.

Impact:
When both TCCs are reset simultaneously, the E100 cards and E1000 cards
stop passing traffic. The G1000 cards traffic would not be affected. TDM
traffic may be compromised because timing is not synchronized anymore. The
protection switching feature is compromised.

Software Versions and Fixes:
This vulnerability is fixed in Cisco ONS software release 3.2.1 and later.

Cisco ONS software release 3.2.1 is the maintenance release fix version
for this vulnerability. Cisco ONS software version 3.3.0 is currently
available as an interim fix release for this vulnerability until Cisco ONS
software version 3.2.1 is released at the end of July 2002.

The procedure to upgrade to the fixed software version on the Cisco ONS
15454 is detailed at:
<http://www.cisco.com/univercd/cc/td/doc/product/ong/15400/r33docs/sftuprgd/index.htm> http://www.cisco.com/univercd/cc/td/doc/product/ong/15400/r33docs/sftuprgd/index.htm.

Obtaining Fixed Software:
Cisco is offering free software upgrades to address this vulnerability for
all affected customers. Customers may only install and expect support for
the feature sets they have purchased.

Customers with service contracts should contact their regular update
channels to obtain the free software upgrade identified via this advisory.
For most customers with service contracts, this means that upgrades should
be obtained through the Software Center on Cisco's worldwide website at
<http://www.cisco.com> http://www.cisco.com.

Customers whose Cisco products are provided or maintained through a prior
or existing agreement with third-party support organizations such as Cisco
Partners, authorized resellers, or service providers should contact that
support organization for assistance with obtaining the free software
upgrade(s).

Customers who purchased directly from Cisco but who do not hold a Cisco
service contract, and customers who purchase through third party vendors
but are unsuccessful at obtaining fixed software through their point of
sale, should obtain fixed software by contacting the Cisco Technical
Assistance Center (TAC) using the contact information listed below. In
these cases, customers are entitled to obtain an upgrade to a later
version of the same release or as indicated by the applicable corrected
software version in the Software Versions and Fixes section (noted above).

Cisco TAC contacts are as follows:
 * +1 800 553 2447 (toll free from within North America)
 * +1 408 526 7209 (toll call from anywhere in the world)
 * e-mail: tac@cisco.com

See <http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml>
http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml for additional
TAC contact information, including special localized telephone numbers and
instructions and e-mail addresses for use in various languages.

Please have your product serial number available and give the URL of this
advisory as evidence of your entitlement to a free upgrade.

Please do not contact either "psirt@cisco.com" or
"security-alert@cisco.com" for software upgrades.

Workarounds:
Restrict IP traffic to the gateway node(s) with a router configured to
change the TOS to zero for all out-bound packets going to the TCC.

Sample Cisco router configuration:
      class-map match-all MY_LAN
      match any
      !--- Matches all packets
      !
      !
      policy-map SET_TOS
      class MY_LAN
      set ip dscp default
      !--- Sets all packets to "00000000" (Best effort)
     
      !
      interface FastEthernet0/0
      service-policy output SET_TOS
      !--- Modifies outbound packets

ADDITIONAL INFORMATION

The information has been provided by <mailto:psirt-support@cisco.com>
Cisco Systems Product Security Incident Response Team.

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