Summary

• A vulnerability in the CLI of Cisco IOS XE SD-WAN Software could allow an authenticated, local attacker to execute arbitrary commands with root privileges.

  The vulnerability is due to insufficient input validation by the system CLI. An attacker could exploit this vulnerability by authenticating to an affected device and submitting crafted input to the system CLI. A successful exploit could allow the attacker to execute commands on the underlying operating system with root privileges.

  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://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sd-wan-rhpbE34A

Affected Products

• Vulnerable Products

  This vulnerability affects the following Cisco products if they are running a vulnerable release of universal Cisco IOS XE Software in Controller mode or a vulnerable release of standalone Cisco IOS XE SD-WAN Software:

  • 1000 Series Integrated Services Routers (ISRs)
  • 4000 Series ISRs
  • ASR 1000 Series Aggregation Services Routers
  • Catalyst 8000 Series Edge Platforms
  • Cloud Services Router (CSR) 1000V Series

  For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.

  Note: The standalone Cisco IOS XE SD-WAN release images are separate from the universal Cisco IOS XE Software release images. The SD-WAN feature was first integrated into universal Cisco IOS XE Software with Release 17.2.1r. For more information, see the Cisco SD-WAN Getting Started Guide.

  Determine the Device Configuration

  There are two methods for determining whether the Controller mode is enabled on a device that is running universal Cisco IOS XE Software. A device must be in Controller mode to use the Cisco SD-WAN feature.

  Option 1: Use the show running-config | include sdwan Command
  

  To determine whether the Controller mode is enabled on a device, use the show running-config | include sdwan command and check tunnel mode in the output. If the command returns tunnel mode sdwan, the SD-WAN feature is enabled. Therefore, the device is in Controller mode and is vulnerable. If the command returns no output or the command does not exist, the device is not affected by this vulnerability.

  The following example shows the output of the show running-config | include sdwan command on a device that is in Controller mode:

  Router# show running-config | include sdwan
  tunnel mode sdwan
  Router#

  Option 2: Use the show version Command
  

  Alternatively, use the show version command to determine whether the device is in Controller mode. The end of the output includes the router operating mode, which indicates whether the device is in Controller mode.

  The following example shows part of the show version command output on a device that is in Controller mode:

  Router# show version
  .
  .
  .
  Router operating mode: Controller-Managed
  .
  .
  .

  Products Confirmed Not Vulnerable

  Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability.

  Universal Cisco IOS XE Software releases earlier than Release 17.2.1r are not affected by this vulnerability because they do not include the SD-WAN feature.

  Cisco has confirmed that this vulnerability does not affect the following Cisco products:

  • IOS Software
  • IOS XE Software that is running in Autonomous Mode
  • SD-WAN vBond Orchestrator Software
  • SD-WAN vEdge Cloud Routers
  • SD-WAN vEdge Routers
  • SD-WAN vManage Software
  • SD-WAN vSmart Controller Software

Workarounds

• There are no workarounds that address this vulnerability.

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

  Standalone IOS XE SD-WAN Software

  Cisco has not released and will not release updates to standalone Cisco IOS XE SD-WAN Software to address the vulnerability described in this advisory. Customers are advised to upgrade to a universal Cisco IOS XE Software release.

  Universal IOS XE Software

  Customers are advised to upgrade to an appropriate fixed software release as indicated in the following table(s):

  Cisco IOS XE Universal Release	First Fixed Release
  16.12 and earlier	Not vulnerable
  17.2	17.2.3
  17.3	17.3.4
  17.4	17.4.2
  17.5	17.5.1a
  17.6	17.6.1

  The Cisco Product Security Incident Response Team (PSIRT) validates only the affected and fixed release information that is documented in this advisory.

Exploitation and Public Announcements

• The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.

Source

• Cisco would like to thank Julien Legras of Synacktiv for reporting this vulnerability.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sd-wan-rhpbE34A

Revision History

• Version	Description	Section	Status	Date
  1.1	Updated metadata to add affected releases to CVRF data.	-	Final	2022-FEB-17
  1.0	Initial public release.	-	Final	2021-OCT-20

  Show Less