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AUSCERT External Security Bulletin Redistribution
ESB-2020.3031
Cisco IOS XR Authenticated User Privilege Escalation Vulnerability
3 September 2020
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: IOS XR
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Administrator Compromise -- Existing Account
Denial of Service -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2020-3530 CVE-2020-3473
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-LJtNFjeN
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-cli-privescl-sDVEmhqv
Comment: This bulletin contains two (2) Cisco Systems security advisories.
- --------------------------BEGIN INCLUDED TEXT--------------------
Cisco IOS XR Software Authenticated User Privilege Escalation Vulnerability
Priority: High
Advisory ID: cisco-sa-iosxr-LJtNFjeN
First Published: 2020 September 2 16:00 GMT
Version 1.0: Final
Workarounds: YesCisco Bug IDs: CSCvs12604
CVE-2020-3473
CWE-264
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 task group assignment for a specific CLI command in
Cisco IOS XR Software could allow an authenticated, local CLI shell user to
elevate privileges and gain full administrative control of the device.
The vulnerability is due to incorrect mapping of a command to task groups
within the source code. An attacker could exploit this vulnerability by
first authenticating to the local CLI shell on the device and using the CLI
command to bypass the task group-based checks. A successful exploit could
allow the attacker to elevate privileges and perform actions on the device
without authorization checks.
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-iosxr-LJtNFjeN
Affected Products
o Vulnerable Products
This vulnerability affects the following Cisco products if they are running
a release of Cisco IOS XR Software Release 5.0.0 or later that is earlier
than the first fixed release:
8000 Series Routers
IOS XRv 9000 Router
IOS XR, SW only
Network Convergence System 540 Routers
Network Convergence System 560 Routers
Network Convergence System 4000 Series
Network Convergence System 5500 Series
Network Convergence System 6000 Series Routers
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:
ASR 9000 Series Aggregation Services Routers (32-bit and 64-bit models)
Carrier Routing System
Network Convergence System 520 Routers
Network Convergence System 1000 Series
Network Convergence System 4200 Series
Network Convergence System 5000 Series
Workarounds
o Workarounds exist only for devices that have TACACS+ authentication,
authorization, and accounting (AAA) command authorization configured.
Administrators can use this feature to permit access to only the commands
that nonadministrative users require and deny access to all other commands.
For more information about Cisco IOS XR task groups and AAA, see ASR9000/XR
Using Task groups and understanding Priv levels and authorization .
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:
Cisco Platform First Fixed Releases
8000 Series Routers 7.0.12, 7.2.1, and later
IOS XRv 9000 Router 6.6.3, 7.0.2, 7.1.1, and
later
IOS XR, SW only 7.0.2, 7.1.1, and later
Network Convergence System 540 Routers 6.6.3, 7.0.2, 7.1.1, and
later
Network Convergence System 560 Routers 6.6.3, 7.0.2, 7.1.1, and
later
Network Convergence System 4000 Series SMU ID for 6.5.29 - AA17787
Network Convergence System 5500 Series 6.6.3, 7.0.2, 7.1.1, and
later
Network Convergence System 6000 Series 6.6.3, 7.0.2, 7.1.1, and
Routers later
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-LJtNFjeN
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2020-SEP-02 |
+----------+---------------------------+----------+--------+--------------+
- --------------------------------------------------------------------------------
Cisco IOS XR Authenticated User Privilege Escalation Vulnerability
Priority: High
Advisory ID: cisco-sa-iosxr-cli-privescl-sDVEmhqv
First Published: 2020 September 2 16:00 GMT
Version 1.0: Final
Workarounds: YesCisco Bug IDs: CSCvu79978CSCvu99038CSCvv05925
CVE-2020-3530
CWE-264
Summary
o A vulnerability in task group assignment for a specific CLI command in
Cisco IOS XR Software could allow an authenticated, local attacker to
execute that command, even though administrative privileges should be
required. The attacker must have valid credentials on the affected device.
The vulnerability is due to incorrect mapping in the source code of task
group assignments for a specific command. An attacker could exploit this
vulnerability by issuing the command, which they should not be authorized
to issue, on an affected device. A successful exploit could allow the
attacker to invalidate the integrity of the disk and cause the device to
restart. This vulnerability could allow a user with read permissions to
issue a specific command that should require Administrator privileges.
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-iosxr-cli-privescl-sDVEmhqv
Affected Products
o Vulnerable Products
This vulnerability affects the following Cisco products if they are running
a vulnerable release of Cisco IOS XR Software:
ASR 9000 Series Aggregation Services Routers (32-bit and 64-bit models)
IOS XR, SW only
Network Convergence System 1000 Series
Network Convergence System 5000 Series
Network Convergence System 5500 Series
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:
8000 Series Routers
Carrier Routing System
IOS XRv 9000 Routers
Network Convergence System 520 Routers
Network Convergence System 540 Series Routers
Network Convergence System 560 Series Routers
Network Convergence System 4000 Series
Network Convergence System 4200 Series
Network Convergence System 6000 Series Routers
Workarounds
o Workarounds exist only for devices that have TACACS+ authentication,
authorization, and accounting (AAA) command authorization configured.
Administrators can use this feature to give nonadministrative users access
to the commands that they require and deny access to all other commands.
For more information about Cisco IOS XR task groups and AAA, see ASR9000/XR
Using Task groups and understanding Priv levels and authorization .
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
Cisco has fixed this vulnerability in Cisco IOS XR releases 7.1.2 and later
for the following platforms:
ASR 9000 Series Aggregation Services Routers (32-bit and 64-bit models)
IOS XR, SW only
Network Convergence System 1000 Series
Network Convergence System 5000 Series
Network Convergence System 5500 Series
Releases earlier than Release 7.0.1 are not vulnerable.
The following software maintenance upgrades (SMUs) are also available.
Customers should install the appropriate SMU as shown in the following
table. Customers who require SMUs for other platforms and releases should
contact their support organization.
IOS XR Release Platform SMU Identifier
7.0.2 ASR9K-X64 AA17739
7.0.2 NCS5500 AA17740
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 Christopher York 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-iosxr-cli-privescl-sDVEmhqv
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2020-SEP-02 |
+----------+---------------------------+----------+--------+--------------+
- --------------------------END INCLUDED TEXT--------------------
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The University of Queensland
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