Summary

• A vulnerability in the IP Version 4 (IPv4) fragment reassembly function of Cisco 3500, 5500, and 8500 Series Wireless LAN Controller Software could allow an unauthenticated, remote attacker to cause an affected device to reload unexpectedly, resulting in a denial of service (DoS) condition.
  
  The vulnerability is due to a corruption of an internal data structure process that occurs when the affected software reassembles certain IPv4 packets. An attacker could exploit this vulnerability by sending certain malformed IPv4 fragments to an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.
  
  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-20180502-wlc-ip

Affected Products

• Vulnerable Products

  This vulnerability affects all releases of 8.4 until the first fixed release for the 5500 and 8500 Series Wireless LAN Controllers and releases 8.5.103.0 and 8.5.105.0 for the 3500, 5500, and 8500 Series Wireless LAN Controllers.

  For information about which Cisco WLC Software releases are vulnerable, see the Fixed Software section of this advisory.

  Determining the Cisco WLC Software Release

  To determine which Cisco WLC Software release is running on a device, administrators can use the controller’s web interface or the CLI.

  To use the web interface, do the following:

  1. By using a browser, log in to the controller’s web interface.
  2. Click the Monitor tab.
  3. Click Summary in the left pane.
  4. Under Controller Summary, the Software Version field shows the release number of the software that is currently running on the device.

  To use the CLI, log in to the controller via Telnet, issue the show sysinfo command, and then refer to the value in the Product Version field of the command output. The following example shows the command output for a device that is running Cisco WLC Software Release 8.3.102.0:

  (wlc)> show sysinfo
  
  Manufacturer's Name.............................. Cisco Systems Inc.
  Product Name..................................... Cisco Controller
  Product Version.................................. 8.3.102.0
  Bootloader Version............................... 1.0.1
  Field Recovery Image Version..................... 6.0.182.0
  Firmware Version................................. FPGA 1.3, Env 1.6, USB console 1.27
  Build Type....................................... DATA + WPS
  .
  .
  .

  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. By using a browser, 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 access point via a Telnet or 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.

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 Wireless LAN Controller 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
  8.1	Not vulnerable	Not vulnerable
  8.2	Not vulnerable	8.5.120.0
  8.3	Not vulnerable	8.5.120.0
  8.4	Affected; migrate to 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

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 the resolution of a Cisco TAC support case.

URL

• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180502-wlc-ip

Revision History

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

  Show Less