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AUSCERT External Security Bulletin Redistribution
ESB-2020.3280
Cisco IOS XE Software for Cisco ASR 900, 1000 Series vulnerabilities
25 September 2020
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco IOS XE Software for Cisco ASR 900 Series
Cisco IOS XE Software for Cisco ASR 1000 Series
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Execute Arbitrary Code/Commands -- Existing Account
Denial of Service -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2020-3513 CVE-2020-3508 CVE-2020-3416
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-rsp3-rce-jVHg8Z7c
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-esp20-arp-dos-GvHVggqJ
Comment: This bulletin contains two (2) Cisco Systems security advisories.
- --------------------------BEGIN INCLUDED TEXT--------------------
Cisco IOS XE Software for Cisco ASR 900 Series Route Switch Processor 3
Arbitrary Code Execution Vulnerabilities
Priority: High
Advisory ID: cisco-sa-iosxe-rsp3-rce-jVHg8Z7c
First Published: 2020 September 24 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCvr69196CSCvs62410
CVE-2020-3416
CVE-2020-3513
CWE-749
Summary
o Multiple vulnerabilities in the initialization routines that are executed
during bootup of Cisco IOS XE Software for Cisco ASR 900 Series Aggregation
Services Routers with a Route Switch Processor 3 (RSP3) installed could
allow an authenticated, local attacker with high privileges to execute
persistent code at bootup and break the chain of trust.
These vulnerabilities are due to incorrect validations by boot scripts when
specific ROM monitor (ROMMON) variables are set. An attacker could exploit
these vulnerabilities by copying a specific file to the local file system
of an affected device and defining specific ROMMON variables. A successful
exploit could allow the attacker to run arbitrary code on the underlying
operating system (OS) with root privileges. To exploit these
vulnerabilities, an attacker would need to have access to the root shell on
the device or have physical access to the device.
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-iosxe-rsp3-rce-jVHg8Z7c
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
These vulnerabilities affect Cisco ASR 900 Series Aggregation Services
Routers with an RSP3 installed 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 these vulnerabilities.
Cisco has confirmed that these vulnerabilities do not affect the following
Cisco products:
IOS Software
IOS XR Software
NX-OS Software
Workarounds
o There are no workarounds that address these vulnerabilities.
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 vulnerabilities that are
described in this advisory.
Source
o These vulnerabilities were found by Victor Kamensky of Cisco and X.B. of
the Cisco Advanced Security Initiatives Group (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.
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-iosxe-rsp3-rce-jVHg8Z7c
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2020-SEP-24 |
+----------+---------------------------+----------+--------+--------------+
- --------------------------------------------------------------------------------
Cisco IOS XE Software for Cisco ASR 1000 Series 20-Gbps Embedded Services
Processor IP ARP Denial of Service Vulnerability
Priority: High
Advisory ID: cisco-sa-esp20-arp-dos-GvHVggqJ
First Published: 2020 September 24 16:00 GMT
Version 1.0: Final
Workarounds: Yes
Cisco Bug IDs: CSCva53392CSCvu04413
CVE-2020-3508
CWE-400
Summary
o A vulnerability in the IP Address Resolution Protocol (ARP) feature of
Cisco IOS XE Software for Cisco ASR 1000 Series Aggregation Services
Routers with a 20-Gbps Embedded Services Processor (ESP) installed could
allow an unauthenticated, adjacent attacker to cause an affected device to
reload, resulting in a denial of service condition.
The vulnerability is due to insufficient error handling when an affected
device has reached platform limitations. An attacker could exploit this
vulnerability by sending a malicious series of IP ARP messages to an
affected device. A successful exploit could allow the attacker to exhaust
system resources, which would eventually cause the affected device to
reload.
Cisco has released software updates that address this vulnerability. There
are workarounds that address this vulnerability.
This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
cisco-sa-esp20-arp-dos-GvHVggqJ
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 Cisco ASR 1000 Series Aggregation Services
Routers with a 20-Gbps ESP installed 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 is a workaround that addresses this vulnerability.
To prevent exploitation of this vulnerability, use the arp entries
interface-limit command in global configuration mode to configure a global
per-interface ARP cache limit, as shown in the following example:
router#conf t
router(config)#arp entries interface-limit 150000
router(config)^Z
router#
Note: Administrators need to calculate the actual global interface limit
value so that the configured value multiplied by the number of connected
interfaces is less than the global ARP cache limit of the platform. The
equation for this calculation is as follows:
configured limit x number of connected interfaces < platform limit
Transposed to the maximum possible global interface limit, this formula is
as follows:
configured limit < platform limit / number of connected interfaces
For the 20-Gbps ESP, that platform limit is 1,000,000 entries. For example,
on a system with six connected interfaces, configure a global per-interface
ARP cache limit of less than 1,000,000 / 6 166,667 entries. In the
example above, the ARP cache limit is 150,000 entries.
To further protect network and system resources, administrators can also
configure this command based on the maximum number of ARP entries that are
expected in the network.
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.
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 the resolution of a Cisco TAC support
case.
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-esp20-arp-dos-GvHVggqJ
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2020-SEP-24 |
+----------+---------------------------+----------+--------+--------------+
- --------------------------END INCLUDED TEXT--------------------
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The University of Queensland
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