Summary

• A vulnerability in the Image Signature Verification feature used in an NX-OS CLI command in Cisco Nexus 3000 Series and 9000 Series Switches could allow an authenticated, local attacker with administrator-level credentials to install a malicious software image on an affected device.
  
  The vulnerability exists because software digital signatures are not properly verified during CLI command execution. An attacker could exploit this vulnerability to install an unsigned software image on an affected device.

  Note: If the device has not been patched for the vulnerability previously disclosed in the Cisco Security Advisory cisco-sa-20190306-nxos-sig-verif, a successful exploit could allow the attacker to boot a malicious software image.

  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-20190515-nxos-sisv

Affected Products

• Vulnerable Products

  This vulnerability affects the following Cisco products if they are running a vulnerable release of Cisco NX-OS Software:

  • Nexus 3000 Series Switches with the following product IDs (PIDs):
    
    • N3K-C3164Q
    • N3K-C3232C
  • Nexus 9000 Series Switches in standalone NX-OS mode with the following PIDs:
    • N9K-C92304QC
    • N9K-C9232C

  Note: This vulnerability affects a limited number of products; only the preceding PIDs are affected by this vulnerability.

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

  Determining the Cisco NX-OS Product ID

  To check the PID, administrators can use the show inventory command in the device CLI. The following example shows the output of the command for a device that has the PID N3K-C3232C:

      switch# show inventory 
      NAME: "Chassis",  DESCR: "Nexus3000 C3232C Chassis"              
      PID: N3K-C3232C          ,  VID: V02 ,  SN: FOC20291JA0          
  
      NAME: "Slot 1",  DESCR: "32x40/100G QSFP28 2x10G SFP+ Ethernet Module"
      PID: N3K-C3232C          ,  VID: V02 ,  SN: FOC20291JA0          
  
      NAME: "Power Supply 1",  DESCR: "Nexus3000 C3232C Chassis Power Supply" 
      PID: NXA-PAC-650W-PI     ,  VID: V01 ,  SN: LIT20362Z6G  

  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:

  • Firepower 2100 Series
  • Firepower 4100 Series
  • Firepower 9300 Security Appliances
  • MDS 9000 Series Multilayer Switches
  • Nexus 1000V Switch for Microsoft Hyper-V
  • Nexus 1000V Switch for VMware vSphere
  • Nexus 3500 Platform Switches
  • Nexus 3600 Platform Switches
  • Nexus 5500 Platform Switches
  • Nexus 5600 Platform Switches
  • Nexus 6000 Series Switches
  • Nexus 7000 Series Switches
  • Nexus 7700 Series Switches
  • Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode
  • Nexus 9500 R-Series Switching Platform
  • UCS 6200 Series Fabric Interconnects
  • UCS 6300 Series Fabric Interconnects
  • UCS 6400 Series Fabric Interconnects

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 and Alerts 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 release as indicated in the following table. In the table, the left column lists the affected PIDs. The first affected Cisco NX-OS Software releases for each PID are in the center column. The right column indicates the first release that includes the fix for this vulnerability.

  Note: A complete fix for this vulnerability requires that a proper BIOS version is installed. Customers who are running a vulnerable PID listed in the following table may not have upgraded the BIOS when the software was installed even if they are running a fixed software release. Customers are advised to confirm that the BIOS is running a fixed BIOS version (first fixed or later) as described in the previously disclosed Cisco Security Advisory cisco-sa-20190306-nxos-sig-verif.

  Nexus 3000 Series Switches and Nexus 9000 Series Switches in Standalone NX-OS Mode: CSCvj14078

  Affected Product ID	First Affected Release for This Vulnerability	First Fixed Releases for This Vulnerability
  N3K-C3164Q	6.1(2)I3(4)	7.0(3)I7(5), 9.2(2)
  N3K-C3232C	7.0(3)I3(1)	7.0(3)I7(1), 9.2(1)
  N9K-C92304QC	7.0(3)I4(1)	7.0(3)I7(5), 9.2(2)
  N9K-C9232C	7.0(3)I4(2)	7.0(3)I7(5), 9.2(2)

  
  

  Additional Resources

  For help determining the best Cisco NX-OS Software release for a Cisco Nexus Switch, administrators can refer to the following Recommended Releases documents. If a security advisory recommends a later release, Cisco recommends following the advisory guidance.

  Cisco MDS Series Switches
  Cisco Nexus 1000V for VMware Switch
  Cisco Nexus 3000 Series and 3500 Series Switches
  Cisco Nexus 5000 Series Switches
  Cisco Nexus 5500 Platform Switches
  Cisco Nexus 6000 Series Switches
  Cisco Nexus 7000 Series Switches
  Cisco Nexus 9000 Series Switches
  Cisco Nexus 9000 Series ACI-Mode Switches

  For help determining the best Cisco NX-OS Software release for Cisco UCS, refer to the Recommended Releases documents in the release notes for the device.

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-20190515-nxos-sisv

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2019-May-15

  Show Less

---