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AUSCERT External Security Bulletin Redistribution
ESB-2021.0389
Cisco 8000 Series Routers and Network Convergence System 540
Series Routers Vulnerabilities
4 February 2021
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco 8000 Series Routers
Cisco Network Convergence System 540 Series Routers
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Execute Arbitrary Code/Commands -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2021-1370 CVE-2021-1244 CVE-2021-1136
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ioxr-l-zNhcGCBt
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-pe-QpzCAePe
Comment: This bulletin contains two (2) security advisories.
- --------------------------BEGIN INCLUDED TEXT--------------------
Cisco IOS XR Software for Cisco 8000 Series Routers and Network Convergence
System 540 Series Routers Image Verification Vulnerabilities
Priority: High
Advisory ID: cisco-sa-ioxr-l-zNhcGCBt
First Published: 2021 February 3 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCvr07463 CSCvs70887
CVE Names: CVE-2021-1136 CVE-2021-1244
CWEs: CWE-347
Summary
o Multiple vulnerabilities in Cisco Network Convergence System (NCS) 540
Series Routers, only when running Cisco IOS XR NCS540L software images, and
Cisco IOS XR Software for the Cisco 8000 Series Routers could allow an
authenticated, local attacker to execute unsigned code during the boot
process on an affected device.
For more information about these vulnerabilities, see the Details section
of this advisory.
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-ioxr-l-zNhcGCBt
Affected Products
o Vulnerable Products
These vulnerabilities affect the following Cisco devices if they are
running a vulnerable release of Cisco IOS XR Software:
8000 Series Routers
NCS 540 Series Routers that are running the NCS540L images
For information about which Cisco software releases are vulnerable, see the
Fixed Software section of this advisory.
Determine the Software Version
To determine whether the device is running an NCS540L software image, log
in to the device and issue the show version command. If the output
indicates LNT, as shown in the following example, then the device is
affected by these vulnerabilities.
Router#show version
Cisco IOS XR Software, Version 7.0.1 LNT
Copyright (c) 2013-2019 by Cisco Systems, Inc.Build Information:
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory
are known to be affected by this vulnerability.
Details
o The vulnerabilities are not dependent on one another. Exploitation of one
of the vulnerabilities is not required to exploit the other vulnerability.
In addition, a software release that is affected by one of the
vulnerabilities may not be affected by the other vulnerability.
Details about the vulnerabilities are as follows:
CVE-2021-1136: Cisco IOS XR Software for Cisco 8000 Series Routers and
Network Convergence System 540 Series Routers GRUB Boot Loader
Vulnerability
A vulnerability in the GRUB boot loader of Cisco NCS 540 Series Routers,
only when running Cisco IOS XR NCS540L software images, and Cisco IOS XR
Software for the Cisco 8000 Series Routers could allow an authenticated,
local attacker to execute unsigned code during the boot process on an
affected device.
The vulnerability is due to an unlocked version of GRUB boot loader on an
affected device. An attacker could exploit this vulnerability by modifying
the boot process from the GRUB menu. A successful exploit could allow the
attacker to bypass the boot chain of trust.
Cisco has released software updates that address this vulnerability. There
are no workarounds that address this vulnerability.
Bug ID(s): CSCvs70887
CVE ID: CVE-2021-1136
Security Impact Rating (SIR): High
CVSS Base Score: 6.7
CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
CVE-2021-1244: Cisco IOS XR Software for Cisco 8000 Series Routers and
Network Convergence System 540 Series Routers Unsigned Boot File
Vulnerability
A vulnerability in the signing functions of ISO packaging of Cisco NCS 540
Series Routers, only when running Cisco IOS XR NCS540L software images, and
Cisco IOS XR Software for the Cisco 8000 Series Routers could allow an
authenticated, local attacker with administrator privileges to execute
unsigned code during the installation of an ISO on an affected device.
The vulnerability is due to an unsigned script within the ISO that is not
verified during system upgrade before it is executed. To exploit this
vulnerability, an attacker could modify an ISO image and then either use
that image to upgrade as an authenticated administrator or place that image
on a file server, which an unsuspecting administrator could then use when
upgrading the device. A successful exploit could allow the attacker to
execute arbitrary code on the affected device.
Cisco has released software updates that address this vulnerability. There
are no workarounds that address this vulnerability.
Bug ID(s): CSCvr07463
CVE ID: CVE-2021-1244
Security Impact Rating (SIR): High
CVSS Base Score: 6.7
CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Workarounds
o There are no workarounds that address these vulnerabilities.
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.
Fixed Releases
The following table shows the first fixed release for each CVE ID:
Affected First Fixed Release for First Fixed Release for
Platform CVE-2021-1136 (CSCvs70887) CVE-2021-1244 (CSCvr07463)
Cisco 8000 7.0.12 7.0.14
Series Routers 7.2.1 7.2.1
Cisco NCS 540 7.2.1 7.1.2
Series Routers 7.2.1
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-ioxr-l-zNhcGCBt
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2021-FEB-03 |
+----------+---------------------------+----------+--------+--------------+
- --------------------------------------------------------------------------------
Cisco IOS XR Software for Cisco 8000 Series Routers and Network Convergence
System 540 Series Routers Privilege Escalation Vulnerability
Priority: High
Advisory ID: cisco-sa-iosxr-pe-QpzCAePe
First Published: 2021 February 3 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCvs35027
CVE Names: CVE-2021-1370
CWEs: CWE-78
CVSS Score:
7.8 AV:L/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 a CLI command of Cisco IOS XR Software for the Cisco
8000 Series Routers and Network Convergence System 540 Series Routers
running NCS540L software images could allow an authenticated, local
attacker to elevate their privilege to root . To exploit this
vulnerability, an attacker would need to have a valid account on an
affected device.
The vulnerability is due to insufficient validation of command line
arguments. An attacker could exploit this vulnerability by authenticating
to the device and entering a crafted command at the prompt. A successful
exploit could allow an attacker with low-level privileges to escalate their
privilege level to root .
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-iosxr-pe-QpzCAePe
Affected Products
o Vulnerable Products
This vulnerability affects Cisco IOS XR Software on the following
platforms:
Cisco 8000 Series Routers if running releases earlier than the first
fixed release.
Network Convergence System 540 Series Routers 7.x releases if running
releases earlier than the first fixed software release and running the
NCS540L images.
Determine the Software Version
To determine if the device is running an NCS540L image, administrators can
log into the device and issue the show version command. If the output
indicates LNT then it is running on an affected device.
Router#show version
Cisco IOS XR Software, Version 7.0.1 LNT
Copyright (c) 2013-2019 by Cisco Systems, Inc.
Build Information:
Built By : xyz
Built On : Sat Jun 29 22:45:27 2019
Build Host : iox-lnx-064
Workspace : ../7.0.1/NCS540L/ws/
Version : 7.0.1
Label : 7.0.1
cisco NCS540L
System uptime is 41 minutes
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.
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.
Fixed Releases
Customers are advised to upgrade to an appropriate fixed software release
as indicated in the following table(s):
Platform Cisco IOS XR Software Release
Cisco 8000 Series Routers 7.0.12
7.2.1
Network Convergence System 540 Series Routers 7.2.1
Cisco has released software maintenance upgrades (SMUs) to address this
vulnerability. Customers who require SMUs for other platforms and releases
are advised to contact their support organization.
Cisco IOS XR Software Release Platform SMU Name
7.1.2 NCS540L ncs540l-7.1.2.CSCvs35027
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-iosxr-pe-QpzCAePe
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2021-FEB-03 |
+----------+---------------------------+----------+--------+--------------+
- --------------------------END INCLUDED TEXT--------------------
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