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Cisco Security Advisory: Cisco uBR10012 Series Devices SNMP Vulnerability

Advisory ID: cisco-sa-20080924-ubr

http://www.cisco.com/warp/public/707/cisco-sa-20080924-ubr.shtml

Revision 1.0

For Public Release 2008 September 24 1600 UTC (GMT)

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Summary =======

Cisco uBR10012 series devices automatically enable Simple Network Management Protocol (SNMP) read/write access to the device if configured for linecard redundancy. This can be exploited by an attacker to gain complete control of the device. Only Cisco uBR10012 series devices that are configured for linecard redundancy are affected.

Cisco has released free software updates that address this vulnerability. Workarounds that mitigate this vulnerability are available.

This advisory is posted at http://www.cisco.com/warp/public/707/cisco-sa-20080924-ubr.shtml

NOTE: The September 24, 2008 IOS Advisory bundled publication includes twelve Security Advisories. Eleven of the advisories address vulnerabilities in Cisco's IOS^ software, and one advisory addresses vulnerabilities in Cisco Unified Communications Manager. Each Advisory lists the releases that correct the vulnerability described in the Advisory. Please reference the following software table to find a release that fixes all published IOS software Advisories as of September 24th, 2008:

http://www.cisco.com/warp/public/707/cisco-sa-20080924-bundle.shtml

Individual publication links are listed below:

* http://www.cisco.com/warp/public/707/cisco-sa-20080924-iosips.shtml * http://www.cisco.com/warp/public/707/cisco-sa-20080924-ssl.shtml * http://www.cisco.com/warp/public/707/cisco-sa-20080924-sip.shtml * http://www.cisco.com/warp/public/707/cisco-sa-20080924-cucm.shtml * http://www.cisco.com/warp/public/707/cisco-sa-20080924-vpn.shtml * http://www.cisco.com/warp/public/707/cisco-sa-20080924-mfi.shtml * http://www.cisco.com/warp/public/707/cisco-sa-20080924-ipc.shtml * http://www.cisco.com/warp/public/707/cisco-sa-20080924-ubr.shtml * http://www.cisco.com/warp/public/707/cisco-sa-20080924-multicast.shtml * http://www.cisco.com/warp/public/707/cisco-sa-20080924-sccp.shtml * http://www.cisco.com/warp/public/707/cisco-sa-20080924-iosfw.shtml * http://www.cisco.com/warp/public/707/cisco-sa-20080924-l2tp.shtml

Affected Products =================

Vulnerable Products +------------------

Cisco uBR10012 series devices that are running Cisco IOS and configured for linecard redundancy are affected. Cisco uBR10012 series devices can be identified by issuing the show version command. The following example shows output from a Cisco uBR10012 series device running Cisco IOS software release 12.3(17b)BC7:

ubr10k#show version | include IOS IOS (tm) 10000 Software (UBR10K-K8P6U2-M), Version 12.3(17b)BC7, RELEASE SOFTWARE (fc1) ubr10k#

Please refer to the document entitled "White Paper: Cisco IOS Reference Guide" for additional information on the Cisco IOS release naming conventions. This document is available at the following link: http://www.cisco.com/warp/public/620/1.html

A Cisco uBR10012 series device configured for linecard redundancy will have a line similar to the following in the output of show running-config command:

member subslot <slot>/<card> working

or

hccp <group> protect <worker-member-id> <worker-ip-address>

Any version of Cisco IOS prior to the versions listed in the Software Versions and Fixes section below is vulnerable.

Products Confirmed Not Vulnerable +--------------------------------

Cisco uBR10012 series devices that are not configured for linecard redundancy are not affected.

Cisco 10000 series devices are not affected even if they are configured for linecard redundancy.

Other uBR platforms are not affected.

No other Cisco products are currently known to be affected by this vulnerability.

Details =======

Cisco uBR10012 series devices need to communicate with an RF Switch when configured for linecard redundancy. This communication is based on SNMP (Simple Network Management Protocol). When linecard redundancy is enabled on a Cisco uBR10012 series device, SNMP is also automatically enabled with a default community string of private that has read/write privileges. Since there are no access restrictions on this community string, it may be exploited by an attacker to gain complete control of the device.

Changing the default community string, adding access restrictions on SNMP or doing both will mitigate this vulnerability. The recommended mitigation is to do both.

This vulnerability is documented in the Cisco Bug ID CSCek57932 and has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2008-3807.

Vulnerability Scoring Details =============================

Cisco has provided scores for the vulnerabilities in this advisory based on the Common Vulnerability Scoring System (CVSS). The CVSS scoring in this Security Advisory is done in accordance with CVSS version 2.0.

CVSS is a standards-based scoring method that conveys vulnerability severity and helps determine urgency and priority of response.

Cisco has provided a base and temporal score. Customers can then compute environmental scores to assist in determining the impact of the vulnerability in individual networks.

Cisco has provided an FAQ to answer additional questions regarding CVSS at

http://www.cisco.com/web/about/security/intelligence/cvss-qandas.html

Cisco has also provided a CVSS calculator to help compute the environmental impact for individual networks at

http://intellishield.cisco.com/security/alertmanager/cvss

CSCek57932 - SNMP enabled after redundancy is configured

CVSS Base Score - 10

Access Vector - Network Access Complexity - Low Authentication - None Confidentiality Impact - Complete Integrity Impact - Complete Availability Impact - Complete

CVSS Temporal Score - 8.3

Exploitability - Functional Remediation Level - Official-Fix Report Confidence - Confirmed

Impact ======

Successful exploitation of the vulnerability may allow an attacker to gain complete control of the device.

Software Versions and Fixes ===========================

When considering software upgrades, also consult http://www.cisco.com/go/psirt and any subsequent advisories to determine exposure and a complete upgrade solution.

In all cases, customers should exercise caution to be certain the devices to be upgraded contain sufficient memory and that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, contact the Cisco Technical Assistance Center (TAC) or your contracted maintenance provider for assistance.

Each row of the Cisco IOS software table (below) names a Cisco IOS release train. If a given release train is vulnerable, then the earliest possible releases that contain the fix (along with the anticipated date of availability for each, if applicable) are listed in the "First Fixed Release" column of the table. The "Recommended Release" column indicates the releases which have fixes for all the published vulnerabilities at the time of this Advisory. A device running a release in the given train that is earlier than the release in a specific column (less than the First Fixed Release) is known to be vulnerable. Cisco recommends upgrading to a release equal to or later than the release in the "Recommended Releases" column of the table.

+-------------------------------------------------------------------+ | Major Release | Availability of Repaired Releases | |--------------------+----------------------------------------------| | Affected | | Recommended | | 12.0-Based | First Fixed Release | Release | | Releases | | | |-------------------------------------------------------------------| | There are no affected 12.0 based releases | |-------------------------------------------------------------------| | Affected | | Recommended | | 12.1-Based | First Fixed Release | Release | | Releases | | | |-------------------------------------------------------------------| | There are no affected 12.1 based releases | |-------------------------------------------------------------------| | Affected | | Recommended | | 12.2-Based | First Fixed Release | Release | | Releases | | | |--------------------+------------------------------+---------------| | 12.2 | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2B | Not Vulnerable | | |--------------------+------------------------------+---------------| | | | 12.2(33)SCA1 | | | | | | | Vulnerable; migrate to any | 12.3(23)BC4 | | 12.2BC | release in 12.3 | | | | | 12.4(15)T7 | | | | | | | | 12.4(18c) | |--------------------+------------------------------+---------------| | 12.2BW | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2BX | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2BY | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2BZ | Not Vulnerable | | |--------------------+------------------------------+---------------| | | | 12.2(33)SCA1 | | | | | | | Vulnerable; migrate to any | 12.3(23)BC4 | | 12.2CX | release in 12.3 | | | | | 12.4(15)T7 | | | | | | | | 12.4(18c) | |--------------------+------------------------------+---------------| | | | 12.2(33)SCA1 | | | | | | | Vulnerable; migrate to any | 12.3(23)BC4 | | 12.2CY | release in 12.3 | | | | | 12.4(15)T7 | | | | | | | | 12.4(18c) | |--------------------+------------------------------+---------------| | 12.2CZ | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2DA | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2DD | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2DX | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2EW | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2EWA | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2EX | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2EY | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2EZ | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2FX | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2FY | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2FZ | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2IRB | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2IXA | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2IXB | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2IXC | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2IXD | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2IXE | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2IXF | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2IXG | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2JA | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2JK | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2MB | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2MC | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2S | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SB | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SBC | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SCA | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SE | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SEA | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SEB | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SEC | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SED | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SEE | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SEF | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SEG | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SG | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SGA | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SL | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SM | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SO | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SRA | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SRB | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SRC | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SU | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SV | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SVA | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SVC | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SVD | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SW | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SX | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SXA | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SXB | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SXD | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SXE | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SXF | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SXH | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SY | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2SZ | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2T | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2TPC | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XA | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XB | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XC | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XD | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XE | Not Vulnerable | | |--------------------+------------------------------+---------------| | | | 12.2(33)SCA1 | | | | | | | Vulnerable; migrate to any | 12.3(23)BC4 | | 12.2XF | release in 12.3 | | | | | 12.4(15)T7 | | | | | | | | 12.4(18c) | |--------------------+------------------------------+---------------| | 12.2XG | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XH | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XI | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XJ | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XK | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XL | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XM | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XN | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XNA | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XNB | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XO | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XQ | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XR | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XS | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XT | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XU | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XV | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2XW | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YA | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YB | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YC | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YD | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YE | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YF | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YG | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YH | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YJ | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YK | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YL | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YM | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YN | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YO | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YP | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YQ | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YR | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YS | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YT | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YU | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YV | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YW | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YX | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YY | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2YZ | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2ZA | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2ZB | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2ZC | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2ZD | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2ZE | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2ZF | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2ZG | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2ZH | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2ZJ | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2ZL | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2ZP | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2ZU | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2ZX | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2ZY | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.2ZYA | Not Vulnerable | | |--------------------+------------------------------+---------------| | Affected | | Recommended | | 12.3-Based | First Fixed Release | Release | | Releases | | | |--------------------+------------------------------+---------------| | 12.3 | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3B | Not Vulnerable | | |--------------------+------------------------------+---------------| | | 12.3(17b)BC8 | | | 12.3BC | | 12.3(23)BC4 | | | 12.3(21)BC | | |--------------------+------------------------------+---------------| | 12.3BW | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3EU | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3JA | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3JEA | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3JEB | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3JEC | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3JK | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3JL | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3JX | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3T | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3TPC | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3VA | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3XA | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3XB | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3XC | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3XD | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3XE | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3XF | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3XG | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3XI | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3XJ | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3XK | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3XL | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3XQ | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3XR | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3XS | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3XU | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3XW | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3XX | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3XY | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3XZ | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3YA | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3YD | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3YF | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3YG | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3YH | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3YI | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3YJ | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3YK | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3YM | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3YQ | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3YS | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3YT | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3YU | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3YX | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3YZ | Not Vulnerable | | |--------------------+------------------------------+---------------| | 12.3ZA | Not Vulnerable | | |--------------------+------------------------------+---------------| | Affected | | Recommended | | 12.4-Based | First Fixed Release | Release | | Releases | | | |-------------------------------------------------------------------| | There are no affected 12.4 based releases | +-------------------------------------------------------------------+

Workarounds ===========

Changing SNMP community string and restricting access +----------------------------------------------------

By default, Cisco uBR10012 series devices that are configured for linecard redundancy use a community string of private. This community string can be changed in Cisco IOS versions 12.3(13)BC and later. It is recommended to change the community string and apply access control restrictions that only permit authorized devices SNMP access to the device.

The following configuration example provides operators with information on changing the community string and adding SNMP access control restrictions using an access control list (ACL).

access-list 90 permit host <RF-Switch-IP-1> access-list 90 permit host <RF-Switch-IP-2> access-list 90 permit host <up-converter-IP-if-exists> access-list 90 deny any

redundancy linecard-group 1 cable rf-switch snmp-community <RF-Switch-SNMP-community>

snmp-server community <RF-Switch-SNMP-community> rw 90

When the SNMP community is changed on a Cisco uBR10012 device, is must also be changed on the RF Switch. It can be changed by the following command:

set SNMP COMMUNITY <RF-Switch-SNMP-community>

If there is an up-converter in the network, the SNMP community used by the up-converter must also be changed after changing the community string on the Cisco uBR10012 device. Information on changing the community string used by the up-converter can be found at the following link:

http://www.cisco.com/en/US/tech/tk86/tk804/technologies_tech_note09186a00801...

If the Cisco IOS version does not support changing the community string, access control restrictions can be applied to the default community string. The following configuration example provides operators with information on applying access control restrictions to the default community string.

access-list 90 permit host <RF-Switch-IP-1> access-list 90 permit host <RF-Switch-IP-2> access-list 90 permit host <up-converter-IP-if-exists> access-list 90 deny any

snmp-server community private rw 90

Using Infrastructure ACLs at Network Boundary +--------------------------------------------

Although it is often difficult to block traffic transiting your network, it is possible to identify traffic which should never be allowed to target your infrastructure devices and block that traffic at the border of your network. iACLs are a network security best practice and should be considered as a long-term addition to good network security as well as a workaround for this specific vulnerability. The iACL example shown below should be included as part of the deployed infrastructure access-list which will protect all devices with IP addresses in the infrastructure IP address range:

!-- Permit SNMP (UDP port 161) packets from trusted hosts !-- destined to infrastructure addresses.

! access-list 150 permit udp TRUSTED_HOSTS MASK INFRASTRUCTURE_ADDRESSES MASK eq 161 !

!-- Deny SNMP (UDP port 161) packets from all other sources !-- destined to infrastructure addresses.

! access-list 150 deny udp any INFRASTRUCTURE_ADDRESSES MASK eq 161 !

!-- Permit/deny all other Layer 3 and Layer 4 traffic in !-- accordance with existing security policies and !-- configurations.

!

!-- Permit all other traffic to transit the device.

! access-list 150 permit ip any any !

!-- Apply iACL to interfaces in the ingress direction.

! interface GigabitEthernet0/0 ip access-group 150 in !

The white paper entitled "Protecting Your Core: Infrastructure Protection Access Control Lists" presents guidelines and recommended deployment techniques for infrastructure protection access lists. This white paper can be obtained here:

http://www.cisco.com/en/US/tech/tk648/tk361/technologies_white_paper09186a00...

Additional Mitigation Techniques +-------------------------------

Additional mitigation techniques that can be deployed on Cisco devices within the network are available in the Cisco Applied Mitigation Bulletin companion document for this advisory, which is available at the following link:

http://www.cisco.com/warp/public/707/cisco-amb-20080924-ipc-and-ubr.shtml

Obtaining Fixed Software ========================

Cisco has released free software updates that address these vulnerabilities. Prior to deploying software, customers should consult their maintenance provider or check the software for feature set compatibility and known issues specific to their environment.

Customers may only install and expect support for the feature sets they have purchased. By installing, downloading, accessing or otherwise using such software upgrades, customers agree to be bound by the terms of Cisco's software license terms found at http://www.cisco.com/en/US/products/prod_warranties_item09186a008088e31f.htm... or as otherwise set forth at Cisco.com Downloads at http://www.cisco.com/public/sw-center/sw-usingswc.shtml

Do not contact psirt@cisco.com or security-alert@cisco.com for software upgrades.

Customers with Service Contracts +-------------------------------

Customers with contracts should obtain upgraded software through their regular update channels. For most customers, this means that upgrades should be obtained through the Software Center on Cisco's worldwide website at http://www.cisco.com.

Customers using Third Party Support Organizations +------------------------------------------------

Customers whose Cisco products are provided or maintained through prior or existing agreements with third-party support organizations, such as Cisco Partners, authorized resellers, or service providers should contact that support organization for guidance and assistance with the appropriate course of action in regards to this advisory.

The effectiveness of any workaround or fix is dependent on specific customer situations, such as product mix, network topology, traffic behavior, and organizational mission. Due to the variety of affected products and releases, customers should consult with their service provider or support organization to ensure any applied workaround or fix is the most appropriate for use in the intended network before it is deployed.

Customers without Service Contracts +----------------------------------

Customers who purchase direct from Cisco but do not hold a Cisco service contract, and customers who purchase through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should acquire upgrades by contacting the Cisco Technical Assistance Center (TAC). 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

Customers should have their product serial number available and be prepared to give the URL of this notice as evidence of entitlement to a free upgrade. Free upgrades for non-contract customers must be requested through the TAC.

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

Exploitation and Public Announcements =====================================

The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability described in this advisory.

This vulnerability was found internally.

Status of this Notice: FINAL ============================

THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.

A stand-alone copy or Paraphrase of the text of this document that omits the distribution URL in the following section is an uncontrolled copy, and may lack important information or contain factual errors.

Distribution ============

This advisory is posted on Cisco's worldwide website at :

http://www.cisco.com/warp/public/707/cisco-sa-20080924-ubr.shtml

In addition to worldwide web posting, a text version of this notice is clear-signed with the Cisco PSIRT PGP key and is posted to the following e-mail and Usenet news recipients.

* cust-security-announce@cisco.com * first-bulletins@lists.first.org * bugtraq@securityfocus.com * vulnwatch@vulnwatch.org * cisco@spot.colorado.edu * cisco-nsp@puck.nether.net * full-disclosure@lists.grok.org.uk * comp.dcom.sys.cisco@newsgate.cisco.com

Future updates of this advisory, if any, will be placed on Cisco's worldwide website, but may or may not be actively announced on mailing lists or newsgroups. Users concerned about this problem are encouraged to check the above URL for any updates.

Revision History ================

+---------------------------------------+ | Revision | | Initial | | 1.0 | 2008-Sep-24 | public | | | | release. | +---------------------------------------+

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_policy.h... This includes instructions for press inquiries regarding Cisco security notices. All Cisco security advisories are available at http://www.cisco.com/go/psirt