[VulnWatch] Cisco Security Advisory: Fixed SNMP Communities and Open UDP Port in Cisco 7920 Wireless IP Phone

From: Cisco Systems Product Security Incident Response Team (psirt_at_cisco.com)
Date: 11/16/05

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    Date: Wed, 16 Nov 2005 17:00:00 +0100
    
    

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    Cisco Security Advisory: Fixed SNMP Communities and Open UDP Port in Cisco 7920
    Wireless IP Phone

    Document ID: 68179

    Advisory ID: cisco-sa-20051116-7920

    http://www.cisco.com/warp/public/707/cisco-sa-20051116-7920.shtml

    Revision 1.0

    For Public Release 2005 November 16 1600 UTC (GMT)

    - ---------------------------------------------------------------------------

    Contents
    ========

        Summary
        Affected Products
        Details
        Impact
        Software Versions and Fixes
        Workarounds
        Obtaining Fixed Software
        Exploitation and Public Announcements
        Status of This Notice: FINAL
        Distribution
        Revision History
        Cisco Security Procedures

    - ---------------------------------------------------------------------------

    Summary
    =======

    The Cisco 7920 Wireless IP Phone provides Voice Over IP service via IEEE
    802.11b Wi-Fi networks and has a form-factor similar to a cordless phone. This
    product contains two vulnerabilities:

    The first vulnerability is an SNMP service with fixed community strings that
    allow remote users to read, write, and erase the configuration of an affected
    device.

    The second vulnerability is an open VxWorks Remote Debugger on UDP port 17185
    that may allow an unauthenticated remote user to access debugging information
    or cause a denial of service.

    Cisco has made free software available to address these vulnerabilities for
    affected customers. There are workarounds available to mitigate the effects of
    the vulnerability.

    This advisory is posted at
    http://www.cisco.com/warp/public/707/cisco-sa-20051116-7920.shtml.

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

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

      * Cisco 7920 Wireless IP Phone, firmware version 2.0 and earlier

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

      * Cisco 7920 Wireless IP Phone, firmware version 2.01

    No other Cisco products are currently known to be affected by these
    vulnerabilities, including other IP telephony products.

    Details
    =======

    Fixed SNMP Community Strings
    +---------------------------

    The Cisco 7920 Wireless IP Phone provides an SNMP service with fixed read-only
    and read-write community strings of "public" and "private", respectively. These
    strings cannot be changed by the user and will allow remote users to issue an
    SNMP GetRequest or SetRequest to the phone. SNMP can be used to retrieve and
    modify the device configuration, including stored user data such as phone book
    entries. To address this vulnerability, Cisco has provided updated software
    that removes the SNMP functionality from this product.

    This issue is documented in Cisco bug ID CSCsb75186 ( registered customers
    only) .

    VxWorks Debugger Port (wdbrpc, 17185/udp)
    +----------------------------------------

    The Cisco 7920 Wireless IP Phone listens on UDP port 17185 to allow connections
    from a VxWorks debugger. This port may allow remote users to collect debugging
    information or conduct a denial of service attack against an affected device.
    To address this vulnerability, Cisco has provided updated software that closes
    UDP port 17185.

    This issue is documented in Cisco bug ID CSCsb38210 ( registered customers
    only) .

    Impact
    ======

    Successful exploitation of these vulnerabilities may result in information
    leakage or denial of service attacks against an affected device. In the case of
    the Fixed SNMP Community Strings vulnerability, an attack may take the form of
    erasure or modification of the device configuration and personal user data.

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

    Cisco has provided free software to address these vulnerabilities; please
    consult the chart below for details.

    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.

    +---------------------------------------------+
    | | Affected | First |
    | Cisco Bug ID | Firmware | Fixed |
    | | Releases | Firmware |
    | | | Release |
    |--------------------+-----------+------------|
    | CSCsb75186 ( | Release | |
    | registered | 1.0(8) | Release |
    | customers only) | and | 1.0(9) |
    | (SNMP) | earlier | |
    |--------------------+-----------+------------|
    | CSCsb38210 ( | Release | |
    | registered | 2.0 and | Release |
    | customers only) | earlier | 2.01 |
    | (VxWorks) | | |
    +---------------------------------------------+

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

      * For sites that restrict Cisco 7920 phones to one or more known subnets,
        Access Control Lists (ACLs) can be used to deny traffic to the affected
        ports.

        The following extended access-list can be adapted to your network. This
        example assumes that all Cisco 7920 phones are connected to the
        192.168.10.0 network and that all SNMP access is to be restricted to a
        management station with the IP address of 10.1.1.1:

            access-list 101 permit udp host 10.1.1.1 192.168.10.0 0.0.0.255
              range 161 162
            access-list 101 permit udp host 10.1.1.1 192.168.10.0 0.0.0.255
              port 17185
            access-list 101 deny udp any 192.168.10.0 0.0.0.255 range 161 162
            access-list 101 deny udp any 192.168.10.0 0.0.0.255 port 17185
            access-list 101 permit ip any any

        The access-list must then be applied to all interfaces using configuration
        commands such as:

            interface ethernet 0/0
            ip access-group 101 in

      * Infrastructure ACLs (iACL)
        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. Infrastructure ACLs are considered 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 white
        paper entitled "Protecting Your Core: Infrastructure Protection Access
        Control Lists" presents guidelines and recommended deployment techniques
        for iACLs:
        http://www.cisco.com/warp/public/707/iacl.html

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

    Cisco has made free software available to address this vulnerability for
    affected customers. 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/public/sw-license-agreement.html,
    or as otherwise set forth at Cisco.com Downloads at
    http://www.cisco.com/public/sw-center/sw-usingswc.shtml.

    Do not contact either "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 agreement 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 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 get
    their 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

    Have your product serial number available and give the URL of this notice as
    evidence of your 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 special localized telephone
    numbers and instructions and e-mail addresses for use in various languages.

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

    This vulnerability was reported to Cisco by Shawn Merdinger and will be
    disclosed on November 16, 2005 at the CSI 32^nd Annual Computer Security
    conference in Washington, DC. The Cisco PSIRT is not aware of any malicious use
    of the vulnerability described in this advisory.

    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-20051116-7920.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-teams@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 | 2005-November-16 | 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.html
    . This includes instructions for press inquiries regarding Cisco security
    notices. All Cisco security advisories are available at
    http://www.cisco.com/go/psirt.

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