Summary

• A vulnerability in the Cisco Aironet 1560, 1800, 2800, and 3800 Series Access Points (APs) software could allow an authenticated, adjacent attacker to cause an affected device to reload unexpectedly, resulting in a denial of service (DoS) condition.

  The vulnerability is due to a deadlock condition that may occur when an affected AP attempts to dequeue aggregated traffic that is destined to an attacker-controlled wireless client. An attacker who can successfully transition between multiple Service Set Identifiers (SSIDs) hosted on the same AP while replicating the required traffic patterns could trigger the deadlock condition. A watchdog timer that detects the condition will trigger a reload of the device, resulting in a DoS condition while the device restarts.

  Cisco has released software updates that address this vulnerability.

  This advisory is available at the following link:
  https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20181017-aironet-dos

Affected Products

• Vulnerable Products

  This vulnerability affects only Cisco 1560, 1800, 2800, and 3800 Series Access Points that are running a vulnerable release of Cisco Mobility Express (ME) Software. For information about affected software releases, consult the Cisco bug ID(s) at the top of this advisory.

  Determining the Cisco Mobility Express Software Release

  To determine which Cisco Mobility Express Software release is running on a device, administrators can use the web interface or the CLI of the device.

  To use the web interface, do the following:

  1. Log in to the web interface
  2. Choose System Software > Software Upgrade
  3. Refer to the value in the System Software Version field

  To use the CLI, log in to the AP through a Telnet or an SSH session, issue the show version command, and then refer to the command output. The following example shows the command output 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
  .
  .
  .

  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:

  • Small Business 100 Series Access Points
  • Small Business 300 Series Access Points
  • Small Business 500 Series Access Points
  • Aironet 1540 Series Access Points

  Note: The Cisco Aironet 1550 Series Outdoor Access Point was not investigated because it has entered the end-of-life process. Refer to the End-of-Sale and End-of-Life Announcement for the Cisco Aironet 1550 Series Outdoor Access Point for additional information.

Workarounds

• There are no workarounds that address this vulnerability.

Fixed Software

• For information about fixed software releases, consult the Cisco bug ID(s) at the top of this advisory.

  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.

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 TAC support case.

URL

• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20181017-aironet-dos

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2018-October-17

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