Summary

• A vulnerability in Cisco Application Policy Infrastructure Controller (APIC) could allow an authenticated, remote attacker to gain higher privileges than the account is assigned. The attacker will be granted the privileges of the last user to log in, regardless of whether those privileges are higher or lower than what should have been granted. The attacker cannot gain root-level privileges.
  
  The vulnerability is due to a limitation with how Role-Based Access Control (RBAC) grants privileges to remotely authenticated users when login occurs via SSH directly to the local management interface of the APIC. An attacker could exploit this vulnerability by authenticating to the targeted device. The attacker's privilege level will be modified to match that of the last user to log in via SSH. An exploit could allow the attacker to gain elevated privileges and perform CLI commands that should be restricted by the attacker's configured role.
  
  Cisco has released software updates that address this vulnerability. There are workarounds that address this vulnerability.
  
  This advisory is available at the following link:
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170816-apic1

Affected Products

• Vulnerable Products

  This vulnerability affects Cisco APIC under the following conditions:
  

  • The attacker uses SSH to connect to the local management interface of the APIC.
  • The attacker uses a remote user credential, which means that the authentication is done by a remote authentication server (for example, TACACS or RADIUS).
  • The attacker has valid user credentials for the remote user.

  Cisco APIC is not vulnerable under these conditions:
  

  • A locally configured user on the device is not vulnerable.
  • If the remote connection to the APIC is done via the Representational State Transfer (REST) API or GUI, the device is not vulnerable. However, if the Launch SSH feature within the GUI is used, it could be vulnerable if remote authentication is used.

  All software versions prior to the first fixed release are vulnerable. For information about fixed software releases, consult the Fixed Software section of this advisory.
  
  To determine which release of APIC is running on a device, administrators can use the CLI command show version. The following example shows the output of the command for a device running software release 1.2(3m):
  

  APIC# show version

   Role        Id          Name                      Version
   ----------  ----------  ------------------------  --------------------
   controller  1           APIC                      1.2(3m)
  .
  .
  .

  
  

  Products Confirmed Not Vulnerable

  No other Cisco products are currently known to be affected by this vulnerability.
  
  Cisco has confirmed that this vulnerability does not affect Cisco Application Policy Infrastructure Controller Enterprise Module (APIC-EM).

Workarounds

• There are workarounds that address this vulnerability. On the remote authentication server, each remote user can be configured with a Cisco Attribute-Value (AV) Pair, which includes a unique UNIX User Identifier. If this AV Pair is not present, then all users are assigned the same default UNIX User Identifier, which results in the vulnerability. For additional information on this configuration, please refer to Externally Managed Authentication Server Users Cisco AV Pair Format. Please contact the Cisco TAC if additional assistance is needed with this configuration.
  
  In addition, while not workarounds, there are mitigations that can be used. This vulnerability only exists when SSH is used to connect to the local management interface of the APIC. If the connection uses the REST API or GUI interface, this vulnerability does not exist.

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 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 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 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 Releases
  
  Customers should upgrade to an appropriate release as indicated in the table in this section. To help ensure a complete upgrade solution, consider that this advisory is part of a collection that includes the following advisories:
  

  • cisco-sa-20170816-apic1: Cisco Application Policy Infrastructure Controller SSH Privilege Escalation Vulnerability
  • cisco-sa-20170816-apic2: Cisco Application Policy Infrastructure Controller Custom Binary Privilege Escalation Vulnerability

  In the following table, the left column lists major releases of Cisco software. The center column indicates whether a major release is affected by the vulnerability described in this advisory and the first minor release that includes the fix for this vulnerability. The right column indicates whether a major release is affected by all the vulnerabilities described in this collection of advisories and the current recommended release for those vulnerabilities.

  Cisco Application Policy Infrastructure Controller	First Fixed Release for This Vulnerability	Recommended Release for This Vulnerability and All Vulnerabilities Described in the Collection of Advisories
  Prior to 2.0	Vulnerable; migrate to 2.2(2e)	2.2(2e)
  2.0	Vulnerable; migrate to 2.2(2e)	2.2(2e)
  2.1	Vulnerable; migrate to 2.2(2e)	2.2(2e)
  2.2	2.2(2e)	2.2(2e)
  2.3	2.3(1f)	2.3(1f)
  3.0 (future release)	Not Vulnerable	Not Vulnerable

  The software updates can be downloaded from the Software Center on Cisco.com by navigating to Products > Cloud and Systems Management > Policy and Automation Controllers > Application Policy Infrastructure Controller (APIC).

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 resolution of a Cisco TAC support case.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170816-apic1

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	-	Final	2017-August-16

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