Summary

• A vulnerability in the web-based user interface (web UI) of Cisco IOS XE Software could allow an authenticated, remote attacker to write arbitrary files to the operating system of an affected device.
  
  The vulnerability is due to insufficient input validation of HTTP requests that are sent to the web UI of the affected software. An attacker could exploit this vulnerability by sending a malicious HTTP request to the web UI of the affected software. A successful exploit could allow the attacker to write arbitrary files to the operating system of an affected device.

  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-20180328-wfw

Affected Products

• Vulnerable Products

  This vulnerability affects Cisco devices that are running a vulnerable release of Cisco IOS XE Software, if the HTTP Server feature is enabled. The default state of the HTTP Server feature is version-dependent.

  For information about which Cisco IOS XE Software releases are vulnerable, consult the Cisco bug ID(s) at the top of this advisory.

  Assessing the HTTP Server Configuration

  To determine whether the HTTP Server feature is enabled for a device, administrators can log in to the device and use the show running-config | include http (secure|server) command in the CLI to check for the presence of the ip http server command or the ip http secure-server command in the global configuration. If either command is present and configured, the HTTP Server feature is enabled for the device.

  The following example shows the output of the show running-config | include http (secure|server) command for a router that has the HTTP Server feature enabled:

  Router# show running-config | include http (secure|server)
  
  ip http server
  ip http secure-server

  Determining the Cisco IOS XE Software Release

  To determine which Cisco IOS XE Software release is running on a device, administrators can log in to the device, use the show version command in the CLI, and then refer to the system banner that appears. If the device is running Cisco IOS XE Software, the system banner displays Cisco IOS Software, Cisco IOS XE Software, or similar text.

  The following example shows the output of the command for a device that is running Cisco IOS XE Software Release 16.2.1 and has an installed image name of CAT3K_CAA-UNIVERSALK9-M:

  ios-xe-device# show version
  
  Cisco IOS Software, Catalyst L3 Switch Software (CAT3K_CAA-UNIVERSALK9-M), Version Denali 16.2.1, RELEASE SOFTWARE (fc1)
  Technical Support: http://www.cisco.com/techsupport
  Copyright (c) 1986-2016 by Cisco Systems, Inc.
  Compiled Sun 27-Mar-16 21:47 by mcpre
  .
  .
  .

  For information about the naming and numbering conventions for Cisco IOS XE Software releases, see the Cisco IOS and NX-OS Software Reference Guide.

  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 IOS Software, Cisco IOS XR Software, or Cisco NX-OS Software.

Workarounds

• There are no workarounds that address this vulnerability.

Fixed Software

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

  For a mapping of Cisco IOS XE Software releases to Cisco IOS Software releases, refer to the Cisco IOS XE 2 Release Notes, Cisco IOS XE 3S Release Notes, or Cisco IOS XE 3SG Release Notes, depending on the Cisco IOS XE Software release.

  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 internal security testing.

URL

• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-wfw

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2018-March-28

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