Cisco Nexus 9000 Series ACI Mode Switch ICMP Record Route Vulnerability

Summary

• A vulnerability in the ICMP implementation in the Cisco Nexus 9000 Series Application Centric Infrastructure (ACI) Mode Switch could allow an unauthenticated, remote attacker to cause the switch to reload, resulting in a denial of service (DoS) condition.
  
  The vulnerability is due to improper handling of an ICMP packet with the IPv4 Type 7 option for record route. An attacker could exploit this vulnerability by sending an ICMP packet with the record route option to an interface on the affected switch. An exploit could allow the attacker to cause a DoS condition because the switch will reload each time the ICMP packet is received.
  
  Cisco has released software updates that address this vulnerability. A workaround that addresses this vulnerability is available.
  
  This advisory is available at the following link: http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160203-n9knci

Affected Products

• Vulnerable Products

  Cisco Nexus 9000 Series ACI Mode Switches running software versions prior to release 11.0(1c) are vulnerable.

  Products Confirmed Not Vulnerable

  No other Cisco products are currently known to be affected by this vulnerability. Cisco Nexus 9000 Series Switches and Cisco Application Policy Infrastructure Controller (APIC) are not affected.

Indicators of Compromise

• This vulnerability will cause the affected device to reload and write a core file. Contact the Cisco Technical Assistance Center (TAC) to review the core file and confirm whether the device has been compromised by this vulnerability.

Workarounds

• The workaround for this vulnerability is to drop all ICMP packets and should not be applied unless the device has been exploited by this vulnerability. This workaround can be applied only when working with the Cisco TAC.
  
  To apply the workaround, the administrator must log in as the root user on the Cisco Nexus 9000 Series ACI Mode Switch. The command iptables -I INPUT 1 -p ICMP -j DROP will drop ICMP packets to the affected switch. The ICMP drop action can be removed with the command iptables -D INPUT 1.

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:
  
  http://www.cisco.com/en/US/docs/general/warranty/English/EU1KEN_.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 consult the Cisco Security Advisories and Responses archive at http://www.cisco.com/go/psirt and review subsequent advisories to determine exposure and a complete upgrade solution.
  
  In all cases, customers should ensure that the devices to upgrade 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 Technical Assistance Center (TAC):
  
  http://www.cisco.com/en/US/support/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 Versions
  
  The Cisco Nexus 9000 Series ACI Mode Switch ICMP Record Route Vulnerability is fixed in versions 11.0(1c) and later. The Cisco Nexus 9000 Series ACI Mode software can be downloaded from the Software Center on Cisco.com by visiting http://www.cisco.com/cisco/software/navigator.html and choosing Downloads Home > Products > Switches > Data Center Switches > Nexus 9000 Series Switches.

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 investigation of a customer issue by the Cisco TAC.

URL

• http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160203-n9knci

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	-	Final	2016-February-03

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