Summary

• Cisco Aironet Access Points (AP) running Cisco IOS® software will send any static Wired Equivalent Privacy (WEP) key in the cleartext to the Simple Network Management Protocol (SNMP) server if the snmp-server enable traps wlan-wep command is enabled. Affected hardware models are the Cisco Aironet 1100, 1200, and 1400 series. This command is disabled by default. The workaround is to disable this command. Any dynamically set WEP key will not be disclosed.

  Cisco Aironet AP models running VxWorks operating system are not affected by this vulnerability. No other Cisco product is affected.

  This advisory will be available at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20031202-SNMP-trap.

Affected Products

• This section provides details on affected products.

  Vulnerable Products

  Cisco Aironet AP 1100, 1200, and 1400 series running Cisco IOS software are affected. The Cisco AP 350 running Cisco IOS software is not affected. APs running VxWorks-based operating system are not affected.

  To determine if you are running Cisco IOS software, type the following command on your workstation, replacing "10.0.0.1" with the IP address of your AP.

  host%telnet 10.0.0.1
  

  If you are not presented with a menu in a graphic form but simply with a prompt (such as ap1200%), then you may be vulnerable.

  To further confirm that you are running Cisco IOS software, type the show version command at the prompt. If the result of the command is similar to the example below, then you are running Cisco IOS software.

  ap1200>show version
  Cisco Internetwork Operating System Software
  IOS (tm) C1200 Software (C1200-K9W7-M), Version 12.2(11)JA1, EARLY DEPLOYMENT RELEASE SOFTWARE (fc1)
  TAC Support: http://www.cisco.com/tac
  Copyright (c) 1986-2003 by cisco Systems, Inc.
  Compiled Mon 07-Jul-03 13:48 by ccai
  Image text-base: 0x00003000, data-base: 0x004D46F4

  If you have determined that Cisco IOS software is being used on the AP, execute the following command.

  ap1200#show running
  .
  .
  .
  .
  snmp-server enable traps tty
  snmp-server enable traps dot11-qos
  snmp-server enable traps wlan-wep    <<<<<<
  ....

  If your configuration contains the line marked with << , then you are vulnerable.

  Products Confirmed Not Vulnerable

  No other Cisco products are currently known to be affected by these vulnerabilities.

Details

• If enabled, the snmp-server enable traps wlan-wep command will send static WEP keys in the cleartext to the SNMP server every time a key is changed or the AP is rebooted. This vulnerability is opportunistic, and the following conditions must be met for the vulnerability to be exploited.

  • The snmp-server enable traps wlan-wep command must be enabled. (It is disabled by default.)
    
  • An adversary must be able to intercept SNMP packets sent from the AP to the SNMP server.
    
  • The AP in question must be rebooted or the static WEP key must be changed.
    

  Under these circumstances, an adversary will be able to intercept all static WEP keys.

  Dynamically configured WEP keys are not affected by this vulnerability and will not be revealed. A WEP key is dynamically configured if you are using one of the Extensible Authentication Protocol (EAP) authentication protocols. The following EAP authentication protocols are currently supported in Cisco APs: LEAP, EAP-TLS, PEAP, EAP-MD5, and EAP-SIM.

  This vulnerability is assigned Cisco Bug ID CSCec55538 ( registered customers only) .

Workarounds

• The workaround is to disable the associated SNMP trap command by typing the following global command.

  ap1200(config)#no snmp-server enable traps wlan-wep
  

  While the above command will stop the AP from sending your WEP key, Cisco recommends that you do not use static WEP keys but use some of the EAP authentication protocols supported by the AP. The WEP scheme itself has several severe drawbacks. For more details regarding wireless LAN security, please see http://www.cisco.com/application/pdf/en/us/guest/netsol/ns386/c649/ccmigration_09186a0080871da5.pdf. The papers there are regarding general wireless security and provide configuration examples.

Fixed Software

• The vulnerable Cisco IOS software releases are 12.2(8)JA, 12.2(11)JA and 12.2(11)JA1.

  The first fixed release is 12.2(13)JA1.

Exploitation and Public Announcements

• The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerabilities described in this advisory. This vulnerability was discovered by Bill Van Devender.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20031202-SNMP-trap

Revision History

• Revision 1.0

  2003-Dec-02

  Initial public release.

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