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===========================================================================
             AUSCERT External Security Bulletin Redistribution

                               ESB-2021.1025
           Cisco IOS XE Software Web UI multiple vulnerabilities
                               25 March 2021

===========================================================================

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

Product:           Cisco IOS XE Software Web UI
                   Cisco IOS XE Software Web UI OS
Publisher:         Cisco Systems
Operating System:  Cisco
Impact/Access:     Root Compromise                 -- Existing Account      
                   Execute Arbitrary Code/Commands -- Existing Account      
                   Increased Privileges            -- Existing Account      
                   Denial of Service               -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2021-1443 CVE-2021-1435 CVE-2021-1403
                   CVE-2021-1356 CVE-2021-1220 

Original Bulletin: 
   https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-webcmdinjsh-UFJxTgZD
   https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-cswsh-FKk9AzT5
   https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-xe-webui-dos-z9yqYQAn
   https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-xe-os-cmd-inj-Ef6TV5e9

Comment: This bulletin contains four (4) Cisco Systems security advisories.

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

Cisco IOS XE Software Web UI Command Injection Vulnerability

Priority:        Medium
Advisory ID:     cisco-sa-iosxe-webcmdinjsh-UFJxTgZD
First Published: 2021 March 24 16:00 GMT
Version 1.0:     Final
Workarounds:     No workarounds available
Cisco Bug IDs:   CSCvq32553
CVE Names:       CVE-2021-1435
CWEs:            CWE-22

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

Summary

  o A vulnerability in the web UI of Cisco IOS XE Software could allow an
    authenticated, remote attacker to inject arbitrary commands that can be
    executed as the root user.

    This vulnerability is due to insufficient input validation. An attacker
    could exploit this vulnerability by sending a crafted request to the web UI
    of an affected device with arbitrary commands injected into a portion of
    the request. A successful exploit could allow the attacker to execute
    arbitrary commands as the root user.

    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-iosxe-webcmdinjsh-UFJxTgZD

Affected Products

  o Vulnerable Products

    At the time of publication, this vulnerability affected Cisco devices if
    they were running a vulnerable release of Cisco IOS XE Software and had the
    web UI feature enabled.

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

    Determine the HTTP Server Configuration

    To determine whether the HTTP Server feature is enabled for a device, log
    in to the device and use the show running-config | include ip http server|
    secure|active 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
    ip http server|secure|active command for a device that has the HTTP Server
    feature enabled:

        Router# show running-config | include ip http server|secure|active
        ip http server
        ip http secure-server

    Note: The presence of either command or both commands in the device
    configuration indicates that the web UI feature is enabled.

    If the ip http server command is present and the configuration also
    contains ip http active-session-modules none , the vulnerability is not
    exploitable over HTTP.

    If the ip http secure-server command is present and the configuration also
    contains ip http secure-active-session-modules none , the vulnerability is
    not exploitable over HTTPS.

    Products Confirmed Not Vulnerable

    Only products listed in the Vulnerable Products section of this advisory
    are known to be affected by this vulnerability.

    Cisco has confirmed that this vulnerability does not affect the following
    Cisco products:

       IOS Software
       IOS XR Software
       NX-OS Software

Workarounds

  o There are no workarounds that address this vulnerability.

Fixed Software

  o When considering software upgrades , customers are advised to regularly
    consult the advisories for Cisco products, which are available from the
    Cisco Security Advisories 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.

    Cisco IOS and IOS XE Software

    To help customers determine their exposure to vulnerabilities in Cisco IOS
    and IOS XE Software, Cisco provides the Cisco Software Checker to identify
    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 the Cisco Software Checker to search advisories in the
    following ways:

       Choose the software and one or more releases
       Upload a .txt file that includes a list of specific releases
       Enter the output of the show version command

    After initiating a search, customers can customize the search to include
    all Cisco Security Advisories, a specific advisory, or all advisories in
    the most recent bundled publication.

    Customers can also use the following form to determine whether a release is
    affected by any Cisco Security Advisory by entering a Cisco IOS or IOS XE
    Software release-for example, 15.1(4)M2 or 3.13.8S :

    [                    ] [Check]

    By default, the Cisco Software Checker includes results only for
    vulnerabilities that have a Critical or High Security Impact Rating (SIR).
    To include results for Medium SIR vulnerabilities, customers can use the
    Cisco Software Checker on Cisco.com and check the Medium check box in the
    drop-down list under Impact Rating when customizing a search.

    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.

URL

  o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-webcmdinjsh-UFJxTgZD

Revision History

  o +----------+---------------------------+----------+--------+--------------+
    | Version  |        Description        | Section  | Status |     Date     |
    +----------+---------------------------+----------+--------+--------------+
    | 1.0      | Initial public release.   | -        | Final  | 2021-MAR-24  |
    +----------+---------------------------+----------+--------+--------------+

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

Cisco IOS XE Software Web UI Cross-Site WebSocket Hijacking Vulnerability

Priority:        High
Advisory ID:     cisco-sa-iosxe-cswsh-FKk9AzT5
First Published: 2021 March 24 16:00 GMT
Version 1.0:     Final
Workarounds:     No workarounds available
Cisco Bug IDs:   CSCvu98441
CVE Names:       CVE-2021-1403
CWEs:            CWE-345

Summary

  o A vulnerability in the web UI feature of Cisco IOS XE Software could allow
    an unauthenticated, remote attacker to conduct a cross-site WebSocket
    hijacking (CSWSH) attack and cause a denial of service (DoS) condition on
    an affected device.

    This vulnerability is due to insufficient HTTP protections in the web UI on
    an affected device. An attacker could exploit this vulnerability by
    persuading an authenticated user of the web UI to follow a crafted link. A
    successful exploit could allow the attacker to corrupt memory on the
    affected device, forcing it to reload and causing a DoS condition.

    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-iosxe-cswsh-FKk9AzT5

    This advisory is part of the March 2021 release of the Cisco IOS and IOS XE
    Software Security Advisory Bundled Publication. For a complete list of the
    advisories and links to them, see Cisco Event Response: March 2021
    Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled
    Publication .

Affected Products

  o Vulnerable Products

    This vulnerability affects Cisco devices if they are running a vulnerable
    release of Cisco IOS XE Software and have the HTTP Server feature enabled.
    The default state of the HTTP Server feature in Cisco IOS XE Software is
    version and platform dependent.

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

    Determine the HTTP Server Configuration

    To determine whether the HTTP Server feature is enabled for a device, log
    in to the device and use the show running-config | include ip http server|
    secure|active 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
    ip http server|secure|active command for a device that has the HTTP Server
    feature enabled:

        Router# show running-config | include ip http server|secure|active
        ip http server
        ip http secure-server

    Note: The presence of either command or both commands in the device
    configuration indicates that the web UI feature is enabled.

    If the ip http server command is present and the configuration also
    contains ip http active-session-modules none , the vulnerability is not
    exploitable over HTTP.

    If the ip http secure-server command is present and the configuration also
    contains ip http secure-active-session-modules none , the vulnerability is
    not exploitable over HTTPS.

    Products Confirmed Not Vulnerable

    Only products listed in the Vulnerable Products section of this advisory
    are known to be affected by this vulnerability.

    Cisco has confirmed that this vulnerability does not affect the following
    Cisco products:

       IOS Software
       IOS XR Software
       NX-OS Software

Workarounds

  o There are no workarounds that address this vulnerability.

    Disabling the HTTP Server feature eliminates the attack vector for this
    vulnerability and may be a suitable mitigation until affected devices can
    be upgraded. To disable the HTTP Server feature, use the no ip http server 
    or no ip http secure-server command in global configuration mode. If both
    the HTTP server and HTTPS server are in use, both commands are required to
    disable the HTTP Server feature.

    While this mitigation has been deployed and was proven successful in a test
    environment, customers should determine the applicability and effectiveness
    in their own environment and under their own use conditions. Customers
    should be aware that any workaround or mitigation that is implemented may
    negatively impact the functionality or performance of their network based
    on intrinsic customer deployment scenarios and limitations. Customers
    should not deploy any workarounds or mitigations before first evaluating
    the applicability to their own environment and any impact to such
    environment.

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 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 the Cisco Software Checker to identify
    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 the Cisco Software Checker to search advisories in the
    following ways:

       Choose the software and one or more releases
       Upload a .txt file that includes a list of specific releases
       Enter the output of the show version command

    After initiating a search, customers can customize the search to include
    all Cisco Security Advisories, a specific advisory, or all advisories in
    the most recent bundled publication.

    Customers can also use the following form to determine whether a release is
    affected by any Cisco Security Advisory by entering a Cisco IOS or IOS XE
    Software release-for example, 15.1(4)M2 or 3.13.8S :

    [                    ] [Check]

    By default, the Cisco Software Checker includes results only for
    vulnerabilities that have a Critical or High Security Impact Rating (SIR).
    To include results for Medium SIR vulnerabilities, customers can use the
    Cisco Software Checker on Cisco.com and check the Medium check box in the
    drop-down list under Impact Rating when customizing a search.

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 Cisco would like to thank Marcin Kopec, Fabian Beck, and Jiri Kulda of
    Deutsche Telekom for reporting this vulnerability.

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.

Related to This Advisory

  o Cisco Event Response: March 2021 Semiannual Cisco IOS and IOS XE Software
    Security Advisory Bundled Publication

URL

  o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-cswsh-FKk9AzT5

Revision History

  o +----------+---------------------------+----------+--------+--------------+
    | Version  |        Description        | Section  | Status |     Date     |
    +----------+---------------------------+----------+--------+--------------+
    | 1.0      | Initial public release.   | -        | Final  | 2021-MAR-24  |
    +----------+---------------------------+----------+--------+--------------+



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

Cisco IOS XE Software Web UI Denial of Service Vulnerabilities

Priority:        Medium
Advisory ID:     cisco-sa-xe-webui-dos-z9yqYQAn
First Published: 2021 March 24 16:00 GMT
Version 1.0:     Final
Workarounds:     No workarounds available
Cisco Bug IDs:   CSCvu94117 CSCvu99729
CVE Names:       CVE-2021-1220 CVE-2021-1356
CWEs:            CWE-20

Summary

  o Multiple vulnerabilities in the web UI of Cisco IOS XE Software could allow
    an authenticated, remote attacker with read -only privileges to cause the
    web UI software to become unresponsive and consume vty line instances,
    resulting in a denial of service (DoS) condition.

    These vulnerabilities are due to insufficient error handling in the web UI.
    An attacker could exploit these vulnerabilities by sending crafted HTTP
    packets to an affected device. A successful exploit could allow the
    attacker to cause the web UI software to become unresponsive and consume
    all available vty lines, preventing new session establishment and resulting
    in a DoS condition. Manual intervention would be required to regain web UI
    and vty session functionality.

    Note: These vulnerabilities do not affect the console connection.

    Cisco has released software updates that address these vulnerabilities.
    There are no workarounds that address these vulnerabilities.

    This advisory is available at the following link:
    https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-xe-webui-dos-z9yqYQAn

Affected Products

  o Vulnerable Products

    At the time of publication, these vulnerabilities affected Cisco devices if
    they were running a vulnerable release of Cisco IOS XE Software and had the
    HTTP Server feature enabled. The default state of the HTTP Server feature
    in Cisco IOS XE Software is version and platform dependent.

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

    Determine the HTTP Server Configuration

    To determine whether the HTTP Server feature is enabled for a device, log
    in to the device and use the show running-config | include ip http server|
    secure|active 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
    ip http server|secure|active command for a device that has the HTTP Server
    feature enabled:

        Router# show running-config | include ip http server|secure|active
        ip http server
        ip http secure-server

    Note: The presence of either command or both commands in the device
    configuration indicates that the web UI feature is enabled.

    If the ip http server command is present and the configuration also
    contains ip http active-session-modules none , these vulnerabilities are
    not exploitable over HTTP.

    If the ip http secure-server command is present and the configuration also
    contains ip http secure-active-session-modules none , these vulnerabilities
    are not exploitable over HTTPS.

    Products Confirmed Not Vulnerable

    Only products listed in the Vulnerable Products section of this advisory
    are known to be affected by these vulnerabilities.

    Cisco has confirmed that these vulnerabilities do not affect the following
    Cisco products:

       IOS Software
       IOS XR Software
       NX-OS Software

Indicators of Compromise

  o Unexpected idle vty sessions may be an indicator that these vulnerabilities
    have been exploited. Use the show user command to display console and vty
    sessions. The initial session that causes these vulnerabilities could
    appear as an idle vty connection with a valid username, such as user1 in
    the examples below. If the attack persists, additional idle vty sessions
    will be displayed in the Host(s) column as HTTP CP . The following example
    shows output from the show user command on a device that has been
    compromised:

        eWLC#show user
           Line      User     Host(s)      Idle       Location
        *  0 con 0            idle         00:00:00
           2 vty 0   user1    idle         00:31:45
           3 vty 1            HTTP CP      00:47:15
           4 vty 2            HTTP CP      00:47:15

    If the web UI is not responding and unexpected idle vty sessions are
    identified, the administrator may be able to clear these lines. Use the
    Idle time as an indicator and not the Host(s) value. Start at the first
    idle vty session and clear each line in succession until all have been
    cleared. All idle lines must be cleared before any listed sessions will
    disappear from the list. Once the last session is cleared, all of these vty
    lines should be freed.

    Use the clear line x command to clear the idle vty sessions. The vty line
    is the left-most number. In this example, the CLI command clear line 2 will
    clear the user1 user session:

        eWLC#clear line 2
           Line      User     Host(s)      Idle       Location
        *  0 con 0            idle         00:00:00
           2 vty 0   user1    idle         00:31:45
           3 vty 1            HTTP CP      00:47:15
           4 vty 2            HTTP CP      00:47:15

    If the vty lines cannot be cleared, the device may need to be reloaded in
    order to restore the web UI and vty session functionality.

Workarounds

  o There are no workarounds that address these vulnerabilities.

    Disabling the HTTP Server feature eliminates the attack vector for these
    vulnerabilities and may be a suitable mitigation until affected devices can
    be upgraded. To disable the HTTP Server feature, use the no ip http server 
    or no ip http secure-server command in global configuration mode. If both
    the HTTP server and HTTPS server are in use, both commands are required to
    disable the HTTP Server feature.

    While this mitigation has been deployed and was proven successful in a test
    environment, customers should determine the applicability and effectiveness
    in their own environment and under their own use conditions. Customers
    should be aware that any workaround or mitigation that is implemented may
    negatively impact the functionality or performance of their network based
    on intrinsic customer deployment scenarios and limitations. Customers
    should not deploy any workarounds or mitigations before first evaluating
    the applicability to their own environment and any impact to such
    environment.

Fixed Software

  o When considering software upgrades , customers are advised to regularly
    consult the advisories for Cisco products, which are available from the
    Cisco Security Advisories 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.

    Cisco IOS and IOS XE Software

    To help customers determine their exposure to vulnerabilities in Cisco IOS
    and IOS XE Software, Cisco provides the Cisco Software Checker to identify
    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 the Cisco Software Checker to search advisories in the
    following ways:

       Choose the software and one or more releases
       Upload a .txt file that includes a list of specific releases
       Enter the output of the show version command

    After initiating a search, customers can customize the search to include
    all Cisco Security Advisories, a specific advisory, or all advisories in
    the most recent bundled publication.

    Customers can also use the following form to determine whether a release is
    affected by any Cisco Security Advisory by entering a Cisco IOS or IOS XE
    Software release-for example, 15.1(4)M2 or 3.13.8S :

    [                    ] [Check]

    By default, the Cisco Software Checker includes results only for
    vulnerabilities that have a Critical or High Security Impact Rating (SIR).
    To include results for Medium SIR vulnerabilities, customers can use the
    Cisco Software Checker on Cisco.com and check the Medium check box in the
    drop-down list under Impact Rating when customizing a search.

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 vulnerabilities that are
    described in this advisory.

Source

  o Cisco would like to thank Marcin Kopec, Fabian Beck, and Jiri Kulda from
    Deutsche Telekom for reporting these vulnerabilities.

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.

URL

  o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-xe-webui-dos-z9yqYQAn

Revision History

  o +----------+---------------------------+----------+--------+--------------+
    | Version  |        Description        | Section  | Status |     Date     |
    +----------+---------------------------+----------+--------+--------------+
    | 1.0      | Initial public release.   | -        | Final  | 2021-MAR-24  |
    +----------+---------------------------+----------+--------+--------------+



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

Cisco IOS XE Software Web UI OS Command Injection Vulnerability

Priority:        Medium
Advisory ID:     cisco-sa-ios-xe-os-cmd-inj-Ef6TV5e9
First Published: 2021 March 24 16:00 GMT
Version 1.0:     Final
Workarounds:     No workarounds available
Cisco Bug IDs:   CSCvu60249
CVE Names:       CVE-2021-1443
CWEs:            CWE-77

Summary

  o A vulnerability in the web UI of Cisco IOS XE Software could allow an
    authenticated, remote attacker to execute arbitrary code with root 
    privileges on the underlying operating system of an affected device.

    The vulnerability exists because the affected software improperly sanitizes
    values that are parsed from a specific configuration file. An attacker
    could exploit this vulnerability by tampering with a specific configuration
    file and then sending an API call. A successful exploit could allow the
    attacker to inject arbitrary code that would be executed on the underlying
    operating system of the affected device. To exploit this vulnerability, the
    attacker would need to have a privileged set of credentials to the device.

    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-ios-xe-os-cmd-inj-Ef6TV5e9

Affected Products

  o Vulnerable Products

    At the time of publication, this vulnerability affected Cisco devices if
    they were running a vulnerable release of Cisco IOS XE Software and had the
    HTTP Server feature enabled. The default state of the HTTP Server feature
    in Cisco IOS XE Software is version and platform dependent.

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

    Determine the HTTP Server Configuration

    To determine whether the HTTP Server feature is enabled for a device, log
    in to the device and use the show running-config | include ip http server|
    secure|active 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
    ip http server|secure|active command for a device that has the HTTP Server
    feature enabled:

        Router# show running-config | include ip http server|secure|active
        ip http server
        ip http secure-server

    Note: The presence of either command or both commands in the device
    configuration indicates that the web UI feature is enabled.

    If the ip http server command is present and the configuration also
    contains ip http active-session-modules none , the vulnerability is not
    exploitable over HTTP.

    If the ip http secure-server command is present and the configuration also
    contains ip http secure-active-session-modules none , the vulnerability is
    not exploitable over HTTPS.

    Products Confirmed Not Vulnerable

    Only products listed in the Vulnerable Products section of this advisory
    are known to be affected by this vulnerability.

Workarounds

  o There are no workarounds that address this vulnerability.

    Disabling the HTTP Server feature eliminates the attack vector for this
    vulnerability and may be a suitable mitigation until affected devices can
    be upgraded. To disable the HTTP Server feature, use the no ip http server 
    or no ip http secure-server command in global configuration mode. If both
    the HTTP server and HTTPS server are in use, both commands are required to
    disable the HTTP Server feature.

    While this mitigation has been deployed and was proven successful in a test
    environment, customers should determine the applicability and effectiveness
    in their own environment and under their own use conditions. Customers
    should be aware that any workaround or mitigation that is implemented may
    negatively impact the functionality or performance of their network based
    on intrinsic customer deployment scenarios and limitations. Customers
    should not deploy any workarounds or mitigations before first evaluating
    the applicability to their own environment and any impact to such
    environment.

Fixed Software

  o When considering software upgrades , customers are advised to regularly
    consult the advisories for Cisco products, which are available from the
    Cisco Security Advisories 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.

    Cisco IOS and IOS XE Software

    To help customers determine their exposure to vulnerabilities in Cisco IOS
    and IOS XE Software, Cisco provides the Cisco Software Checker to identify
    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 the Cisco Software Checker to search advisories in the
    following ways:

       Choose the software and one or more releases
       Upload a .txt file that includes a list of specific releases
       Enter the output of the show version command

    After initiating a search, customers can customize the search to include
    all Cisco Security Advisories, a specific advisory, or all advisories in
    the most recent bundled publication.

    Customers can also use the following form to determine whether a release is
    affected by any Cisco Security Advisory by entering a Cisco IOS or IOS XE
    Software release-for example, 15.1(4)M2 or 3.13.8S :

    [                    ] [Check]

    By default, the Cisco Software Checker includes results only for
    vulnerabilities that have a Critical or High Security Impact Rating (SIR).
    To include results for Medium SIR vulnerabilities, customers can use the
    Cisco Software Checker on Cisco.com and check the Medium check box in the
    drop-down list under Impact Rating when customizing a search.

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 by X.B. of Cisco 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.

URL

  o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-xe-os-cmd-inj-Ef6TV5e9

Revision History

  o +----------+---------------------------+----------+--------+--------------+
    | Version  |        Description        | Section  | Status |     Date     |
    +----------+---------------------------+----------+--------+--------------+
    | 1.0      | Initial public release.   | -        | Final  | 2021-MAR-24  |
    +----------+---------------------------+----------+--------+--------------+

- --------------------------END INCLUDED TEXT--------------------

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