Summary

• 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://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-LJtNFjeN

Affected Products

• 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

• 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

• 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 Routers	6.6.3, 7.0.2, 7.1.1, and later

Exploitation and Public Announcements

• 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

• This vulnerability was found during internal security testing.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-LJtNFjeN

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	-	Final	2020-SEP-02

  Show Less