ESB-2018.0913.2 - UPDATE ALERT [Cisco] Cisco IOS and Cisco IOS XE: Execute arbitrary code/commands - Remote/unauthenticated 2018-04-16

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             AUSCERT External Security Bulletin Redistribution

                              ESB-2018.0913.2
       Cisco IOS and IOS XE Software Quality of Service Remote Code
                          Execution Vulnerability
                               16 April 2018

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        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           Cisco IOS
                   Cisco IOS XE
Publisher:         Cisco Systems
Operating System:  Cisco
Impact/Access:     Execute Arbitrary Code/Commands -- Remote/Unauthenticated
                   Increased Privileges            -- Remote/Unauthenticated
                   Denial of Service               -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2018-0151  

Original Bulletin: 
   https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-qos

Revision History:  April 16 2018: Update to revision 1.2
                   March 29 2018: Initial Release

- --------------------------BEGIN INCLUDED TEXT--------------------

Cisco Security Advisory

Cisco IOS and IOS XE Software Quality of Service Remote Code Execution
Vulnerability

Critical

Advisory ID:     cisco-sa-20180328-qos

First Published: 2018 March 28 16:00 GMT

Last Updated:    2018 April 13 15:36 GMT

Version 1.2:     Final

Workarounds:     Yes

Cisco Bug IDs:
CSCvf73881

CVE-2018-0151

CWE-119

CVSS Score:
9.8  AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:X/RL:X/RC:X

Summary

  o A vulnerability in the quality of service (QoS) subsystem of Cisco IOS
    Software and Cisco IOS XE Software could allow an unauthenticated, remote
    attacker to cause a denial of service (DoS) condition or execute arbitrary
    code with elevated privileges.

    The vulnerability is due to incorrect bounds checking of certain values in
    packets that are destined for UDP port 18999 of an affected device. An
    attacker could exploit this vulnerability by sending malicious packets to
    an affected device. When the packets are processed, an exploitable buffer
    overflow condition may occur. A successful exploit could allow the attacker
    to execute arbitrary code on the affected device with elevated privileges.
    The attacker could also leverage this vulnerability to cause the device to
    reload, causing a temporary DoS condition while the device is reloading.

    The malicious packets must be destined to and processed by an affected
    device. Traffic transiting a device will not trigger the vulnerability.

    Cisco has released software updates that address this vulnerability. There
    are workarounds that address this vulnerability.

    This advisory is available at the following link:
    https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
    cisco-sa-20180328-qos

    This advisory is part of the March 28, 2018, release of the Cisco IOS and
    IOS XE Software Security Advisory Bundled Publication, which includes 20
    Cisco Security Advisories that describe 22 vulnerabilities. For a complete
    list of the advisories and links to them, see Cisco Event Response: March
    2018 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled
    Publication.

Affected Products

  o Vulnerable Products

    This vulnerability affects Cisco devices that are running a vulnerable
    release of Cisco IOS Software or Cisco IOS XE Software.

    For information about which Cisco IOS and IOS XE Software releases are
    vulnerable, see the Fixed Software section of this advisory.

    Assessing a Device

    To determine whether a device that is running Cisco IOS Software or
    Cisco IOS XE Software may be affected by this vulnerability, administrators
    can log in to the device and use the show udp command in the CLI.

    The device may be affected by this vulnerability if the command returns
    output similar to the following example:

        Router> show udp

        Proto  Remote   Port   Local   Port  In Out  Stat TTY OutputIF
        17     0.0.0.0   0    --any--  18999  0   0    11   0

    The Adaptive QoS for Dynamic Multipoint VPN (DMVPN) feature of Cisco IOS
    Software and Cisco IOS XE Software uses UDP port 18999 and may be open due
    to the provisioning of this feature on unaffected platforms. If UDP port
    18999 is bound to a listening port on a device, use the Cisco IOS Software
    Checker to determine whether the device is running a vulnerable software
    release.

    Determining the Cisco IOS Software Release

    To determine which Cisco IOS Software release is running on a device,
    administrators can log in to the device, use the show version command in
    the CLI, and then refer to the system banner that appears. If the device is
    running Cisco IOS Software, the system banner displays text similar to
    Cisco Internetwork Operating System Software or Cisco IOS Software. The
    banner also displays the installed image name in parentheses, followed by
    the Cisco IOS Software release number and release name. Some Cisco devices
    do not support the show version command or may provide different output.

    The following example shows the output of the command for a device that is
    running Cisco IOS Software Release 15.5(2)T1 and has an installed image
    name of C2951-UNIVERSALK9-M:

        Router> show version

        Cisco IOS Software, C2951 Software (C2951-UNIVERSALK9-M), Version 15.5(2)T1, RELEASE SOFTWARE (fc1)
        Technical Support: http://www.cisco.com/techsupport
        Copyright (c) 1986-2015 by Cisco Systems, Inc.
        Compiled Mon 22-Jun-15 09:32 by prod_rel_team
        .
        .
        .

    For information about the naming and numbering conventions for Cisco IOS
    Software releases, see the Cisco IOS and NX-OS Software Reference Guide.

    Determining the Cisco IOS XE Software Release

    To determine which Cisco IOS XE Software release is running on a device,
    administrators can log in to the device, use the show version command in
    the CLI, and then refer to the system banner that appears. If the device is
    running Cisco IOS XE Software, the system banner displays Cisco IOS
    Software, Cisco IOS XE Software, or similar text.

    The following example shows the output of the command for a device that is
    running Cisco IOS XE Software Release 16.2.1 and has an installed image
    name of CAT3K_CAA-UNIVERSALK9-M:

        ios-xe-device# show version

        Cisco IOS Software, Catalyst L3 Switch Software (CAT3K_CAA-UNIVERSALK9-M), Version Denali 16.2.1, RELEASE SOFTWARE (fc1)
        Technical Support: http://www.cisco.com/techsupport
        Copyright (c) 1986-2016 by Cisco Systems, Inc.
        Compiled Sun 27-Mar-16 21:47 by mcpre
        .
        .
        .

    For information about the naming and numbering conventions for Cisco IOS XE
    Software releases, see the Cisco IOS and NX-OS Software Reference Guide.

    Products Confirmed Not Vulnerable

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

    Cisco has confirmed that this vulnerability does not affect Cisco IOS XR
    Software or Cisco NX-OS Software.

Workarounds

  o Customers who do not use the Adaptive QoS for DMVPN feature can deny all
    traffic destined to UDP port 18999 on an affected device by using a Control
    Plane Policing (CoPP) policy similar to the following:

        ! -- ACL for CoPP Undesireable UDP class-map
        ! -- Ignore fragments to prevent them from being misclassified by the policy
          access-list 199 deny ip any any fragments
        ! -- Classify traffic destined to UDP Port 18999 so that we can drop it prior to being processed
          access-list 199 permit udp any any eq 18999

        ! -- CoPP Undesireable UDP class-map
        class-map match-all undesireable-udp
         match access-group 199

        ! -- Undesireable UDP Policy Map
        policy-map drop-udp
         class undesireable-udp
          drop

        ! -- Apply Undesireable UDP policy Map
        control-plane
         service-policy input drop-udp

    On platforms that do not support the drop keyword within the Policy Map,
    customers may consider utilizing a policy similar to the following as an
    alternative:

        ! -- ACL for CoPP Undesirable UDP class-map
        ! -- Ignore fragments to prevent them from being misclassified by the policy
          access-list 199 deny ip any any fragments
        ! -- Classify traffic destined to UDP Port 18999 so that we can drop it prior to being processed
          access-list 199 permit udp any any eq 18999

        ! -- CoPP Undesireable UDP class-map
        class-map match-all undesireable-udp
         match access-group 199

        ! -- Undesireable UDP Policy Map - Drop on Police Rate
        policy-map drop-udp
         class undesireable-udp
          police rate 8000
           conform-action drop
           exceed-action drop
           violate-action drop

        ! -- Apply Undesireable UDP policy Map
        control-plane
         service-policy input drop-udp

    If the Adaptive QoS for DMVPN feature is later configured, the device must
    be upgraded to an unaffected release of Cisco IOS Software or Cisco IOS XE
    Software and the CoPP policy must be removed.

    Customers integrating this workaround into their environment are encouraged
    to test the adaptation in their lab prior to deployment and to reference
    the CoPP Best Practice Document at the following link: https://
    www.cisco.com/c/en/us/about/security-center/copp-best-practices.html

Fixed Software

  o Cisco has released free software updates that address the vulnerability
    described in this advisory. Customers may only install and expect support
    for software versions and feature sets for which they have purchased a
    license. By installing, downloading, accessing, or otherwise using such
    software upgrades, customers agree to follow the terms of the Cisco
    software license:
    https://www.cisco.com/c/en/us/products/end-user-license-agreement.html

    Additionally, customers may only download software for which they have a
    valid license, procured from Cisco directly, or through a Cisco authorized
    reseller or partner. In most cases this will be a maintenance upgrade to
    software that was previously purchased. Free security software updates do
    not entitle customers to a new software license, additional software
    feature sets, or major revision upgrades.

    When considering software upgrades, customers are advised to regularly
    consult the advisories for Cisco products, which are available from the
    Cisco Security Advisories and Alerts page, to determine exposure and a
    complete upgrade solution.

    In all cases, customers should ensure that the devices to be upgraded
    contain sufficient memory and confirm that current hardware and software
    configurations will continue to be supported properly by the new release.
    If the information is not clear, customers are advised to contact the Cisco
    Technical Assistance Center (TAC) or their contracted maintenance
    providers.

    Customers Without Service Contracts

    Customers who purchase directly from Cisco but do not hold a Cisco service
    contract and customers who make purchases through third-party vendors but
    are unsuccessful in obtaining fixed software through their point of sale
    should obtain upgrades by contacting the Cisco TAC:
    https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html

    Customers should have the product serial number available and be prepared
    to provide the URL of this advisory as evidence of entitlement to a free
    upgrade.

    Cisco IOS and IOS XE Software

    To help customers determine their exposure to vulnerabilities in Cisco IOS
    and IOS XE Software, Cisco provides a tool, the Cisco IOS Software Checker,
    that identifies any Cisco Security Advisories that impact a specific
    software release and the earliest release that fixes the vulnerabilities
    described in each advisory ("First Fixed"). If applicable, the tool also
    returns the earliest release that fixes all the vulnerabilities described
    in all the advisories identified ("Combined First Fixed").

    Customers can use this tool to perform the following tasks:

      - Initiate a search by choosing one or more releases from a drop-down
        list or uploading a file from a local system for the tool to parse
      - Enter the output of the show version command for the tool to parse
      - Create a custom search by including all previously published Cisco
        Security Advisories, a specific advisory, or all advisories in the most
        recent bundled publication

    For a mapping of Cisco IOS XE Software releases to Cisco IOS Software
    releases, refer to the Cisco IOS XE 2 Release Notes, Cisco IOS XE 3S
    Release Notes, or Cisco IOS XE 3SG Release Notes, depending on the
    Cisco IOS XE Software release.

Exploitation and Public Announcements

  o The Cisco Product Security Incident Response Team (PSIRT) is not aware of
    any public announcements or malicious use of the vulnerability that is
    described in this advisory.

Source

  o This vulnerability was found during internal security testing.

Cisco Security Vulnerability Policy

  o To learn about Cisco security vulnerability disclosure policies and
    publications, see the Security Vulnerability Policy. This document also
    contains instructions for obtaining fixed software and receiving security
    vulnerability information from Cisco.

Action Links for This Advisory

  o Snort Rule 46111
    Cisco IOS and IOS XE Software Quality of Service Remote Code Execution

Related to This Advisory

  o Cisco Event Response: March 2018 Semiannual Cisco IOS and IOS XE Software
    Security Advisory Bundled Publication
    Cisco Security Blog: Cisco IOS and IOS XE Software Bundled Publication
    March 2018

URL

  o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
    cisco-sa-20180328-qos

Revision History

  o 
    +---------+----------------------------+-------------+--------+---------------+
    | Version |        Description         |   Section   | Status |     Date      |
    +---------+----------------------------+-------------+--------+---------------+
    |         | Fixed typos in the         |             |        |               |
    |         | workarounds section; added |             |        |               |
    | 1.2     | comments to explain what   | Workarounds | Final  | 2018-April-13 |
    |         | the access-control lists   |             |        |               |
    |         | are doing.                 |             |        |               |
    +---------+----------------------------+-------------+--------+---------------+
    |         | Updated Workarounds        |             |        |               |
    |         | section with an updated    |             |        |               |
    |         | CoPP policy that includes  |             |        |               |
    |         | an additional Access-List  |             |        |               |
    |         | Entry addressing           |             |        |               |
    |         | fragmented packets that    |             |        |               |
    | 1.1     | may have caused issues     | Workarounds | Final  | 2018-April-12 |
    |         | when integrated into       |             |        |               |
    |         | existing CoPP policies;    |             |        |               |
    |         | Alternative Policy Map for |             |        |               |
    |         | platforms that do not      |             |        |               |
    |         | support the deny keyword   |             |        |               |
    |         | added.                     |             |        |               |
    +---------+----------------------------+-------------+--------+---------------+
    | 1.0     | Initial public release.    | --          | Final  | 2018-March-28 |
    +---------+----------------------------+-------------+--------+---------------+

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