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             AUSCERT External Security Bulletin Redistribution

                               ESB-2020.3296
                   Cisco IOS XE Software vulnerabilities
                             25 September 2020

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

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

Product:           Cisco IOS XE Software
Publisher:         Cisco Systems
Operating System:  Cisco
Impact/Access:     Root Compromise                 -- Existing Account
                   Execute Arbitrary Code/Commands -- Existing Account
                   Overwrite Arbitrary Files       -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2020-3476 CVE-2020-3404 CVE-2020-3403

Original Bulletin: 
   https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-file-overwrite-Ynu5PrJD
   https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-cmdinj-2MzhjM6K
   https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-ctbypass-7QHAfHkK

Comment: This bulletin contains three (3) Cisco Systems security advisories.

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

Cisco IOS XE Software Arbitrary File Overwrite Vulnerability

Priority:        Medium

Advisory ID:     cisco-sa-file-overwrite-Ynu5PrJD

First Published: 2020 September 24 16:00 GMT

Version 1.0:     Final

Workarounds:     No workarounds available

Cisco Bug IDs:   CSCvn18213

CVE-2020-3476    

CWE-552

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

Summary

  o A vulnerability in the CLI implementation of a specific command of Cisco
    IOS XE Software could allow an authenticated, local attacker to overwrite
    arbitrary files in the underlying host file system.

    The vulnerability is due to insufficient validation of the parameters of a
    specific CLI command. An attacker could exploit this vulnerability by
    issuing that command with specific parameters. A successful exploit could
    allow the attacker to overwrite the content of any arbitrary file that
    resides on the underlying host file system.

    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-file-overwrite-Ynu5PrJD

Affected Products

  o Vulnerable Products

    At the time of publication, this vulnerability affected Cisco devices if
    they were running an affected version of Cisco IOS XE Software.

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

    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 Software

    To help customers determine their exposure to vulnerabilities in Cisco IOS
    Software, Cisco provides the Cisco Software Checker to identify any Cisco
    Security Advisories that impact a specific Cisco IOS 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 use the following form to determine whether a release is
    affected by any Cisco Security Advisory by entering a Cisco IOS Software
    release-for example, 15.1(4)M2 :

    [                    ] [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-file-overwrite-Ynu5PrJD

Revision History

  o +----------+---------------------------+----------+--------+--------------+
    | Version  |        Description        | Section  | Status |     Date     |
    +----------+---------------------------+----------+--------+--------------+
    | 1.0      | Initial public release.   | -        | Final  | 2020-SEP-24  |
    +----------+---------------------------+----------+--------+--------------+

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

Cisco IOS XE Software Command Injection Vulnerability

Priority:        Medium

Advisory ID:     cisco-sa-iosxe-cmdinj-2MzhjM6K

First Published: 2020 September 24 16:00 GMT

Version 1.0:     Final

Workarounds:     No workarounds available

Cisco Bug IDs:   CSCvs07077

CVE-2020-3403    

CWE-78

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

Summary

  o A vulnerability in the CLI of Cisco IOS XE Software could allow an
    authenticated, local attacker to inject a command to the underlying
    operating system that will execute with root privileges upon the next
    reboot of the device. The authenticated user must have privileged EXEC
    permissions on the device.

    The vulnerability is due to insufficient protection of values passed to a
    script that executes during device startup. An attacker could exploit this
    vulnerability by writing values to a specific file. A successful exploit
    could allow the attacker to execute commands with root privileges each time
    the affected device is restarted.

    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-cmdinj-2MzhjM6K

Affected Products

  o Vulnerable Products

    At the time of publication, this vulnerability affected devices if they
    were running a vulnerable release of Cisco IOS XE Software.

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

    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 by JG of Cisco ASIG 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-cmdinj-2MzhjM6K

Revision History

  o +----------+---------------------------+----------+--------+--------------+
    | Version  |        Description        | Section  | Status |     Date     |
    +----------+---------------------------+----------+--------+--------------+
    | 1.0      | Initial public release.   | -        | Final  | 2020-SEP-24  |
    +----------+---------------------------+----------+--------+--------------+



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

Cisco IOS XE Software Consent Token Bypass Vulnerability

Priority:        Medium

Advisory ID:     cisco-sa-iosxe-ctbypass-7QHAfHkK

First Published: 2020 September 24 16:00 GMT

Version 1.0:     Final

Workarounds:     No workarounds available

Cisco Bug IDs:   CSCvq91055

CVE-2020-3404    

CWE-863

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

Summary

  o A vulnerability in the persistent Telnet/Secure Shell (SSH) CLI of Cisco
    IOS XE Software could allow an authenticated, local attacker to gain shell
    access on an affected device and execute commands on the underlying
    operating system (OS) with root privileges.

    The vulnerability is due to insufficient enforcement of the consent token
    in authorizing shell access. An attacker could exploit this vulnerability
    by authenticating to the persistent Telnet/SSH CLI on an affected device
    and requesting shell access. A successful exploit could allow the attacker
    to gain shell access on the affected device and execute commands on the
    underlying OS with root privileges.

    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-ctbypass-7QHAfHkK

Affected Products

  o Vulnerable Products

    At the time of publication, this vulnerability affected devices if they
    were running a vulnerable release of Cisco IOS XE Software and had the
    persistent Telnet or persistent SSH feature configured.

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

    Determine the Device Configuration

    To determine whether the persistent Telnet feature is enabled for a device,
    administrators can log in to the device and use the show running-config |
    include transport type persistent telnet command in the CLI to check for
    the presence of the transport type persistent telnet input < name > command
    in the global configuration.

    To determine whether the persistent SSH feature is enabled for a device,
    administrators can log in to the device and use the show running-config |
    include transport type persistent ssh command in the CLI to check for the
    presence of the transport type persistent ssh input < name > command in the
    global configuration.

    If both commands return no output or an error message, persistent Telnet
    and persistent SSH are not configured on the device and it is not
    vulnerable.

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

    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 by XB of Cisco ASIG 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-ctbypass-7QHAfHkK

Revision History

  o +----------+---------------------------+----------+--------+--------------+
    | Version  |        Description        | Section  | Status |     Date     |
    +----------+---------------------------+----------+--------+--------------+
    | 1.0      | Initial public release.   | -        | Final  | 2020-SEP-24  |
    +----------+---------------------------+----------+--------+--------------+

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

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