Protect yourself against future threats.
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256
===========================================================================
AUSCERT External Security Bulletin Redistribution
ESB-2020.3293.4
Cisco IOS XE Software Arbitrary Code Execution Vulnerability
3 November 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
Resolution: Patch/Upgrade
CVE Names: CVE-2020-3423 CVE-2020-3417
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-xbace-OnCEbyS
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-lua-rce-7VeJX4f
Comment: This bulletin contains two (2) Cisco Systems security advisories.
Revision History: November 3 2020: Vendor updated Fixed Software section in cisco-sa-xbace-OnCEbyS
October 26 2020: vendor issue minor update for cisco-sa-xbace-OnCEbyS
October 1 2020: Clarified the products confirmed not vulnerable
September 25 2020: Initial Release
- --------------------------BEGIN INCLUDED TEXT--------------------
Cisco IOS XE Software Arbitrary Code Execution Vulnerability
Priority: High
Advisory ID: cisco-sa-xbace-OnCEbyS
First Published: 2020 September 24 16:00 GMT
Last Updated: 2020 November 2 15:15 GMT
Version 1.3: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCvs58715
CVE-2020-3417
CWE-78
Summary
o A vulnerability in Cisco IOS XE Software could allow an authenticated,
local attacker to execute persistent code at boot time and break the chain
of trust.
This vulnerability is due to incorrect validations by boot scripts when
specific ROM monitor (ROMMON) variables are set. An attacker could exploit
this vulnerability by installing code to a specific directory in the
underlying operating system (OS) and setting a specific ROMMON variable. A
successful exploit could allow the attacker to execute persistent code on
the underlying OS. To exploit this vulnerability, the attacker would need
access to the root shell on the device or have physical access 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-xbace-OnCEbyS
This advisory is part of the September 24, 2020, release of the Cisco IOS
and IOS XE Software Security Advisory Bundled Publication, which includes
25 Cisco Security Advisories that describe 34 vulnerabilities. For a
complete list of the advisories and links to them, see Cisco Event
Response: September 2020 Semiannual Cisco IOS and IOS XE Software Security
Advisory Bundled Publication .
Affected Products
o Vulnerable Products
This vulnerability affects devices if they are 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 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.
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.
Cisco has released software maintenance upgrades (SMUs) to address this
vulnerability. Customers are advised to install the appropriate SMU as
shown in the following table. Customers who require SMUs for other
platforms and releases are advised to contact their support organization.
Cisco IOS XE Platform SMU Name
Software
Release
16.12.03a Catalyst 3850 cat3k_caa-universalk9.16.12.03a.CSCvs58715
Series Switches
Catalyst 9300/
16.12.03a 9400/9500 Series cat9k_iosxe.16.12.03a.CSCvs58715.SPA.smu.bin
Switches
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 by X.B. of
the Cisco Advanced Security Initiatives Group (ASIG).
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: September 2020 Semiannual Cisco IOS and IOS XE
Software Security Advisory Bundled Publication
URL
o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
cisco-sa-xbace-OnCEbyS
Revision History
o +---------+------------------------+---------------+--------+-------------+
| Version | Description | Section | Status | Date |
+---------+------------------------+---------------+--------+-------------+
| 1.3 | Added SMU information. | Fixed | Final | 2020-NOV-02 |
| | | Software | | |
+---------+------------------------+---------------+--------+-------------+
| 1.2 | Added SMU information. | Fixed | Final | 2020-OCT-23 |
| | | Software | | |
+---------+------------------------+---------------+--------+-------------+
| 1.1 | Updated the CVSS | Header | Final | 2020-SEP-30 |
| | score. | | | |
+---------+------------------------+---------------+--------+-------------+
| 1.0 | Initial public | - | Final | 2020-SEP-24 |
| | release. | | | |
+---------+------------------------+---------------+--------+-------------+
- --------------------------------------------------------------------------------
Cisco IOS XE Software Arbitrary Code Execution Vulnerability
Priority: Medium
Advisory ID: cisco-sa-ios-lua-rce-7VeJX4f
First Published: 2020 September 24 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCvs58804
CVE-2020-3423
CWE-119
Summary
o A vulnerability in the implementation of the Lua interpreter that is
integrated in Cisco IOS XE Software could allow an authenticated, local
attacker to execute arbitrary code with root privileges on the underlying
Linux operating system (OS) of an affected device.
The vulnerability is due to insufficient restrictions on Lua function calls
within the context of user-supplied Lua scripts. An attacker with valid
administrative credentials could exploit this vulnerability by submitting a
malicious Lua script. When this file is processed, an exploitable buffer
overflow condition could occur. A successful exploit could allow the
attacker to execute arbitrary code with root privileges on the underlying
Linux OS of the affected 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-lua-rce-7VeJX4f
Affected Products
o Vulnerable Products
At the time of publication, this vulnerability affected the following Cisco
routers if they were running a vulnerable release of Cisco IOS XE Software:
4000 Series Integrated Services Routers
ASR 1000 Series Aggregation Services Routers
Cloud Services Router 1000V Series
Integrated Services Virtual Routers
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
Details
o At the time of publication, this vulnerability had been identified in the
Cisco Unified Border Element (SP Edition) feature of Cisco IOS XE Software.
This feature allows administrators to define policies to control the VoIP
signaling and media that pass through the device. Cisco Unified Border
Element (SP Edition) offers the capability of defining enhanced policies by
using the Lua programming language. These user-defined Lua scripts are
executed within the scripting sandbox of the device.
However, the local implementation of the Lua interpreter imposes
insufficient restrictions on the allowed Lua function calls within the
scripting sandbox of the affected device. An attacker who has valid
administrative credentials can submit a malicious Lua script that, when
executed, will escape the scripting sandbox and execute arbitrary code with
root privileges on the underlying Linux OS of an affected device.
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 Jean Bernard Beuque 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-lua-rce-7VeJX4f
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2020-SEP-24 |
+----------+---------------------------+----------+--------+--------------+
- --------------------------END INCLUDED TEXT--------------------
You have received this e-mail bulletin as a result of your organisation's
registration with AusCERT. The mailing list you are subscribed to is
maintained within your organisation, so if you do not wish to continue
receiving these bulletins you should contact your local IT manager. If
you do not know who that is, please send an email to auscert@auscert.org.au
and we will forward your request to the appropriate person.
NOTE: Third Party Rights
This security bulletin is provided as a service to AusCERT's members. As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content. The decision to follow or act on information or advice
contained in this security bulletin is the responsibility of each user or
organisation, and should be considered in accordance with your organisation's
site policies and procedures. AusCERT takes no responsibility for consequences
which may arise from following or acting on information or advice contained in
this security bulletin.
NOTE: This is only the original release of the security bulletin. It may
not be updated when updates to the original are made. If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the author's website to ensure that the information is still current.
Contact information for the authors of the original document is included
in the Security Bulletin above. If you have any questions or need further
information, please contact them directly.
Previous advisories and external security bulletins can be retrieved from:
https://www.auscert.org.au/bulletins/
===========================================================================
Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072
Internet Email: auscert@auscert.org.au
Facsimile: (07) 3365 7031
Telephone: (07) 3365 4417 (International: +61 7 3365 4417)
AusCERT personnel answer during Queensland business hours
which are GMT+10:00 (AEST).
On call after hours for member emergencies only.
===========================================================================
-----BEGIN PGP SIGNATURE-----
Comment: http://www.auscert.org.au/render.html?it=1967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=s7NU
-----END PGP SIGNATURE-----