ESB-2018.0905 - [Cisco] Cisco IOS XE: Increased privileges - Existing account 2018-03-29

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2018.0905
           Cisco IOS XE Software Web UI Remote Access Privilege
                         Escalation Vulnerability
                               29 March 2018

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

Product:           Cisco IOS XE
Publisher:         Cisco Systems
Operating System:  Cisco
Impact/Access:     Increased Privileges -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2018-0152  

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

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Cisco Security Advisory

Cisco IOS XE Software Web UI Remote Access Privilege Escalation Vulnerability

High

Advisory ID:     cisco-sa-20180328-xepriv

First Published: 2018 March 28 16:00 GMT

Version 1.0:     Final

Workarounds:     No workarounds available

Cisco Bug IDs:
CSCvf71769

CVE-2018-0152

CWE-264

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

Summary

  o A vulnerability in the web-based user interface (web UI) of Cisco IOS XE
    Software could allow an authenticated, remote attacker to gain elevated
    privileges on an affected device.

    The vulnerability exists because the affected software does not reset the
    privilege level for each web UI session. An attacker who has valid
    credentials for an affected device could exploit this vulnerability by
    remotely accessing a VTY line to the device. A successful exploit could
    allow the attacker to access an affected device with the privileges of the
    user who previously logged in to the web UI.

    Cisco has released software updates that address this vulnerability. There
    are no workarounds that address this vulnerability.

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

    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 XE Software, if the HTTP Server feature is enabled and
    authentication, authorization, and accounting (AAA) authorization is not
    configured for EXEC sessions. The default state of the HTTP Server feature
    is version-dependent.

    This vulnerability was introduced in Cisco IOS XE Software Release 16.1.1.
    For more information about which Cisco IOS XE Software releases are
    vulnerable, see the Fixed Software section of this advisory.

    Assessing the HTTP Server Configuration

    To determine whether the HTTP Server feature is enabled for a device,
    administrators can log in to the device and use the show running-config |
    include http (secure|server) command in the CLI to check for the presence
    of the ip http server command or the ip http secure-server command in the
    global configuration. If either command is present and configured, the HTTP
    Server feature is enabled for the device.

    The following example shows the output of the show running-config | include
    http (secure|server) command for a router that has the HTTP Server feature
    enabled:

        Router# show running-config | include http (secure|server)

        ip http server
        ip http secure-server

    Assessing the AAA Configuration

    To determine whether AAA authorization for EXEC sessions is configured for
    a device, administrators can log in to the device and use the show
    running-config | include aaa authorization exec command in the CLI to check
    for the presence of the aaa authorization exec [options] command in the
    global configuration.

    The following example shows the output of the show running-config | include
    aaa authorization exec command for a router that is configured to have its
    AAA authorization enforced by a TACACS+ server and is therefore not
    affected by this vulnerability:

        Router# show running-config | include aaa authorization exec

        aaa authorization exec use-tacacs group tacacs+

    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
    Software, Cisco IOS XR Software, or Cisco NX-OS Software.

Indicators of Compromise

  o Administrators may identify exploitation of this vulnerability by using the
    AAA accounting logs for an affected system to identify users who are
    executing commands at a higher privilege level than their assigned
    privilege level.

Workarounds

  o There are no workarounds that address this vulnerability.

    Administrators who do not require the web UI may mitigate this
    vulnerability by disabling the HTTP Server feature on an affected device.
    To disable the feature, use the no ip http server and no ip http
    secure-server commands in the CLI.

    Administrators who require the web UI may mitigate this vulnerability by
    enabling AAA authorization for EXEC sessions, locally or via a AAA server,
    for an affected device.

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

    To determine whether a release is affected by any published Cisco Security
    Advisory, use the Cisco IOS Software Checker on Cisco.com or enter a
    Cisco IOS Software or Cisco IOS XE Software release--for example, 15.1(4)M2
    or 3.13.8S--in the following field:

    [                    ] [Check]

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.

Subscribe to Cisco Security Notifications

  o Subscribe

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-xepriv

Revision History

  o 
    +----------+----------------------------+----------+---------+----------------+
    | Version  |        Description         | Section  | Status  |      Date      |
    +----------+----------------------------+----------+---------+----------------+
    | 1.0      | Initial public release.    | --       | Final   | 2018-March-28  |
    +----------+----------------------------+----------+---------+----------------+

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