Summary

• A vulnerability in the assignment and management of default user accounts for Secure Shell (SSH) access to Cisco Aironet 1800, 2800, and 3800 Series Access Points that are running Cisco Mobility Express Software could allow an authenticated, remote attacker to gain elevated privileges on an affected access point.

  The vulnerability exists because the Cisco Mobility Express controller of the affected software configures the default SSH user account for an access point to be the first SSH user account that was created for the Mobility Express controller, if an administrator added user accounts directly to the controller instead of using the default configuration or the SSH username creation wizard. Although the user account has read-only privileges for the Mobility Express controller, the account could have administrative privileges for an associated access point. An attacker who has valid user credentials for an affected controller could exploit this vulnerability by using the default SSH user account to authenticate to an affected access point via SSH. A successful exploit could allow the attacker to log in to the affected access point with administrative privileges and perform arbitrary administrative actions.

  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-20180502-aironet-ssh

Affected Products

• Vulnerable Products

  This vulnerability affects the following Cisco products:

  • Aironet 1800 Series Access Points that are running Cisco Mobility Express Software Releases 8.2.121.0 through 8.5.105.0
  • Aironet 2800 Series Access Points that are running Cisco Mobility Express Software Releases 8.3.102.0 through 8.5.105.0
  • Aironet 3800 Series Access Points that are running Cisco Mobility Express Software Releases 8.3.102.0 through 8.5.105.0

  Determining the Software Release

  To determine which Cisco Mobility Express Software release is running on a Cisco Mobility Express controller and the associated access points, administrators can use the controller’s web interface or the access point’s CLI.

  To use the controller's web interface, do the following:

  1. By using a browser, log in to the web interface.
  2. Choose Management > Software Update.
  3. Refer to the release number that appears at the top of the page.

  To use the access point's CLI, log in to the access point via Telnet or SSH, issue the show version command, and then refer to the output of the command. The following example shows the output of the command for a Cisco Aironet 1852i Access Point that is running Cisco Mobility Express Software Release 8.3.111.0:

  AP# show version
  
  cisco AIR-AP1852I-UXK9 ARMv7 Processor rev 0 (v71) with 997184/525160K bytes of memory.
  Processor board ID RFDP2BCR021
  AP Running Image : 8.3.111.0
  Primary Boot Image : 8.3.111.0
  Backup Boot Image : 8.1.106.33
  AP Image type : MOBILITY EXPRESS IMAGE
  AP Configuration : MOBILITY EXPRESS CAPABLE
  .
  .
  .

  Assessing User Accounts and Privileges

  To display user accounts for a Cisco Mobility Express configuration and assess whether an access point may be vulnerable, administrators can log in to the Cisco Mobility Express controller, use the show mgmtuser command in the CLI, and then refer to the output of the command:

  • If the first user account listed in the output is admin and that account has read-write permissions, the access point is not vulnerable.
  • If the first user account listed in the output has read-only permissions or is the lobby ambassador admin (lobby-admin) account, the access point is vulnerable.

  The following example shows the output of the command for a configuration that is not vulnerable:

  (wlc)> show mgmtuser
  
  User Name     Permissions    Description      Password Strength   Telnet Capable
  -----------   ------------   ---------------  ------------------  ----------
  admin         read-write                      Strong              Yes
  test          read-write                      Strong              Yes

  
  

  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 Cisco Aironet Access Points that are running Cisco Lightweight Access Point (AP) Software or Cisco IOS Software. Cisco has also confirmed that this vulnerability does not affect any Cisco Wireless Controller models or Cisco Wireless LAN Controller models.

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 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-20180502-aironet-ssh: Cisco Aironet 1800, 2800, and 3800 Series Access Points Secure Shell Privilege Escalation Vulnerability
  • cisco-sa-20180502-ap-ptp: Cisco Aironet 1810, 1830, and 1850 Series Access Points Point-to-Point Tunneling Protocol Denial of Service Vulnerability
  • cisco-sa-20180502-wlc-ip: Cisco Wireless LAN Controller IP Fragment Reassembly Denial of Service Vulnerability
  • cisco-sa-20180502-wlc-mfdos: Cisco Wireless LAN Controller 802.11 Management Frame Denial of Service 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 which release includes fixes for those vulnerabilities.

  Cisco Mobility Express Software Major Release	First Fixed Release for This Vulnerability	First Fixed Release for All Vulnerabilities Described in the Collection of Advisories
  Prior to 8.0	Not vulnerable	Not vulnerable
  8.0	Not vulnerable	Not vulnerable
  8.1	Not vulnerable	Not vulnerable
  8.2	8.5.110.01	8.5.120.0
  8.3	8.5.110.02	8.5.120.0
  8.4	8.5.110.0	8.5.120.0
  8.5	8.5.110.0	8.5.120.0
  8.6	Not vulnerable	Not vulnerable
  8.7	Not vulnerable	Not vulnerable

  1. This vulnerability affects only Cisco Aironet 1800 Series Access Points that are running Releases 8.2.121.0 through 8.5.105.0. Cisco Aironet 2800 and 3800 Series Access Points are not vulnerable if they are running Release 8.2.x.

  2. This vulnerability affects only Cisco Aironet 2800 and 3800 Series Access Points that are running Releases 8.3.102.0 through 8.5.105.0.

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-20180502-aironet-ssh

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	-	Final	2018-May-02

  Show Less