A vulnerability in the Secure Copy Protocol (SCP) server of Cisco Enterprise NFV Infrastructure Software (NFVIS) could allow an authenticated, remote attacker to access the shell of the underlying Linux operating system on the affected device. The vulnerability is due to improper input validation of command arguments. An attacker could exploit this vulnerability by using crafted arguments when opening a connection to the affected device. An exploit could allow the attacker to gain shell access with a non-root user account to the underlying Linux operating system on the affected device. Due to the system design, access to the Linux shell could allow execution of additional attacks that may have a significant impact on the affected system. 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://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180516-nfvis
A vulnerability in the Secure Copy Protocol (SCP) server of Cisco Enterprise NFV Infrastructure Software (NFVIS) could allow an authenticated, remote attacker to access the shell of the underlying Linux operating system on the affected device.
The vulnerability is due to improper input validation of command arguments. An attacker could exploit this vulnerability by using crafted arguments when opening a connection to the affected device. An exploit could allow the attacker to gain shell access with a non-root user account to the underlying Linux operating system on the affected device.
Due to the system design, access to the Linux shell could allow execution of additional attacks that may have a significant impact on the affected system.
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://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180516-nfvis
This vulnerability affects Cisco devices that are running release 3.7.1, 3.6.3, or earlier releases of Cisco Enterprise NFV Infrastructure Software (NFVIS) when access to the SCP server is allowed on the affected device.
Cisco NFVIS Releases 3.5.x and 3.6.x do allow access to the SCP server by default, while Cisco NFVIS Release 3.7.1 does not.
Determining the Cisco NFVIS Release
To determine which Cisco NFVIS release is running on a device, administrators can use the show version command in the CLI.
The following example shows the output of the show version command on a device that is running Cisco NFVIS release 3.7.1:
encs# show version
version name "Cisco NFV Infrastructure Software"
version version 3.7.1-FC2
.
.
.
Determining Whether the Device Has Allowed Access to the SCP Server
Cisco NFVIS Release 3.7.1 allows access to the SCP server only if the system settings ip-receive-acl CLI configuration command is applied to the scpd service with an accept action.
The following example shows the output of the show running-config | begin ip-receive-acl CLI command on a device that is running NFVIS Release 3.7.1 and on which access to the SCP server is allowed for clients in the 192.0.2.0/24 IP range:
encs# show running-config | begin ip-receive-acl
system settings ip-receive-acl 192.0.2.0/24
service [ scpd ]
action accept
.
.
.
Cisco NFVIS Releases 3.5.x and 3.6.x do not support the system settings ip-receive-acl CLI configuration command. Access to the SCP server is always allowed in these releases and cannot be disabled.
Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability.
There are no workarounds that address this vulnerability.
Customers who are running Cisco NFVIS Releases 3.5.x or 3.6.x that do not require the use of the SCP server are advised to use an external firewall to restrict access to TCP port 22222 on the affected device.
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
This vulnerability has been corrected in Cisco NFVIS Release 3.8.1 and later.
Cisco NFVIS can be downloaded from the Software Center on Cisco.com by clicking Browse all and navigating to Downloads Home > Routers > Network Functions Virtualization > Enterprise NFV Infrastructure Software > NFV Infrastructure Software.
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.
This vulnerability was found during internal security testing.
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.
| Version | Description | Section | Status | Date |
|---|---|---|---|---|
| 1.0 | Initial public release. | - | Final | 2018-May-16 |
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