Cisco Security Advisory
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CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:X/RL:X/RC:X
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A vulnerability in the Secure Configuration Validation functionality of Cisco FXOS Software and Cisco NX-OS Software could allow an authenticated, local attacker to run arbitrary commands at system boot time with the privileges of root.
The vulnerability is due to a lack of proper validation of system files when the persistent configuration information is read from the file system. An attacker could exploit this vulnerability by authenticating to the device and overwriting the persistent configuration storage with malicious executable files. An exploit could allow the attacker to run arbitrary commands at system startup and those commands will run as the root user. The attacker must have valid administrative credentials for the device.
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-conf-bypass
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Vulnerable Products
This vulnerability affects the following Cisco products if they are running a vulnerable release of Cisco FXOS or NX-OS Software:
- Firepower 4100 Series
- Firepower 9300 Security Appliances
- MDS 9000 Series Multilayer Switches
- Nexus 3000 Series Switches
- 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 Switches in standalone NX-OS mode
- Nexus 9500 R-Series Switching Platform
For information about which Cisco FXOS or NX-OS Software releases are vulnerable, see the Fixed Software section of this advisory.
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
- Nexus 1000V Switch for Microsoft Hyper-V
- Nexus 1000V Switch for VMware vSphere
- Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode
- UCS 6200 Series Fabric Interconnects
- UCS 6300 Series Fabric Interconnects
- UCS 6400 Series Fabric Interconnects
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There are no workarounds that address this vulnerability.
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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
No upgrade action is necessary for customers who have already applied a recommended release to address the March 2019 Cisco FXOS and NX-OS Software bundle. See Cisco Event Response: March 2019 Cisco FXOS and NX-OS Software Security Advisory Bundled Publication for a list of advisories in the bundle.
Customers who have not applied a recommended release to address the March 2019 bundle are advised to upgrade to an appropriate release as indicated in the applicable table in this section. In the following tables, the left column lists Cisco FXOS and NX-OS Software releases. The right column indicates the first release that includes the fix for this vulnerability.
Firepower 4100 Series and Firepower 9300 Security Appliances: CSCvi96584
Cisco FXOS Software Release First Fixed Release for This Vulnerability Prior to 2.4 2.4.1.101 2.4 2.4.1.101 MDS 9000 Series Multilayer Switches: CSCvi96578
Cisco NX-OS Software Release First Fixed Release for This Vulnerability 5.2 6.2(29) 6.2 6.2(29) 8.1 8.1(1b) 8.2 8.2(1) 8.3 8.3(1) Nexus 3000 Series Switches and Nexus 9000 Series Switches in Standalone NX-OS Mode: CSCvh20223
Cisco NX-OS Software Release First Fixed Release for This Vulnerability Prior to 7.0(3)I7 7.0(3)I7(3) 7.0(3)I7 7.0(3)I7(3) 9.2(1) Not vulnerable Nexus 3500 Platform Switches: CSCvi96579
Cisco NX-OS Software Release First Fixed Release for This Vulnerability Prior to 6.0(2)A8 6.0(2)A8(11) 6.0(2)A8 6.0(2)A8(11) 7.0(3) 7.0(3)I7(3) 9.2 Not vulnerable Nexus 3600 Platform Switches and Nexus 9500 R-Series Switching Platform: CSCvi96577
Cisco NX-OS Software Release First Fixed Release for This Vulnerability 7.0(3) 7.0(3)F3(5) 9.2 Not vulnerable Nexus 5500, 5600, and 6000 Series Switches: CSCvi96580
Cisco NX-OS Software Release First Fixed Release for This Vulnerability Prior to 7.3 7.3(4)N1(1) 7.3 7.3(4)N1(1) Nexus 7000 and 7700 Series Switches: CSCvi96578
Cisco NX-OS Software Release First Fixed Release for This Vulnerability Prior to 6.2 6.2(22) 6.2 6.2(22) 7.2 7.3(3)D1(1) 7.3 7.3(3)D1(1) 8.0 8.3(1) 8.1 8.3(1) 8.2 8.3(1) 8.3 8.3(1) 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.
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.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
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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.
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This vulnerability was found during internal security testing.
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To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
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Show LessVersion Description Section Status Date 1.3 Updated the fixed release information for MDS 9000 Series Multilayer Switches. — Final 2021-JUL-12 1.2 Removed the Bug identifier CSCvi96583 for UCS. General Final 2020-FEB-24 1.1 Moved the UCS 6200 and 6300 Series Fabric Interconnects to the list in Products Confirmed Not Vulnerable and removed fixed software tables for those products. Vulnerable Products, Products Confirmed Not Vulnerable, Fixed Software Final 2020-FEB-21 1.0 Initial public release. — Final 2019-MAY-15
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