Summary

• A vulnerability in the Cisco IOS XE ROM Monitor (ROMMON) Software for Cisco 4000 Series Integrated Services Routers, Cisco ASR 920 Series Aggregation Services Routers, Cisco ASR 1000 Series Aggregation Services Routers, and Cisco cBR-8 Converged Broadband Routers could allow an unauthenticated, physical attacker to break the chain of trust and load a compromised software image on an affected device.

  The vulnerability is due to the presence of a debugging configuration option in the affected software. An attacker could exploit this vulnerability by connecting to an affected device through the console, forcing the device into ROMMON mode, and writing a malicious pattern using that specific option on the device. A successful exploit could allow the attacker to break the chain of trust and load a compromised software image on the affected device. A compromised software image is any software image that has not been digitally signed by Cisco.

  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-rommon-secboot-7JgVLVYC

Affected Products

• Vulnerable Products

  This vulnerability affects the following Cisco routers if they are running a vulnerable release of Cisco IOS XE ROMMON Software:

  • 4000 Series Integrated Services Routers
  • ASR 920 Series Aggregation Services Routers
  • ASR 1000 Series Aggregation Services Routers
  • cBR-8 Converged Broadband Routers

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

  Determine the Cisco IOS XE ROMMON Software Release

  To determine which Cisco IOS XE ROMMON Software release is running on a device, log in to the device and use the show platform | begin Firmware or the show rom-monitor rp active command in the CLI. The following example shows the output of those commands for a device that is running Cisco IOS XE ROMMON Software Release 16.7(5r):

  router # show platform | begin Firmware
  Slot      CPLD Version        Firmware Version
  --------- ------------------- ---------------------------------------
  0         14101324            16.7(5r)
  1         14101324            16.7(5r)
  R0        14101324            16.7(5r)
  F0        14101324            16.7(5r)
  
  router # show rom-monitor rp active
  
  System Bootstrap, Version 16.7(5r), RELEASE SOFTWARE
  Copyright (c) 1994-2019  by cisco Systems, Inc.

   

  Products Confirmed Not Vulnerable

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

Workarounds

• There are no workarounds that address this vulnerability.

Fixed Software

• Cisco has released free software updates that address the vulnerabilities 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 Routers	First Fixed Cisco IOS XE ROMMON Software Release
  4000 Series Integrated Services Routers	16.2(1r)
  ASR 920 Series Routers	15.6(18r)
  ASR 1000 Series Routers	16.2(1r)
  cBR-8 Converged Broadband Routers	16.4(1r)S

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-rommon-secboot-7JgVLVYC

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2020-SEP-24

  Show Less

---