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Cisco Aironet Access Points (AP) running Cisco IOS? software will send any static Wired Equivalent Privacy (WEP) key in the clear text 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. |
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Credit:
This advisory is available at http://www.cisco.com/warp/public/707/cisco-sa-20031202-SNMP-trap.shtml.
The information has been provided by Cisco Systems Product Security Incident Response Team.
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Affected 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.
Details:
If enabled, the SNMP-server enable traps wlan-wep command will send static WEP keys in the clear text 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.
Impact:
By being able to intercept a static WEP key, an attacker can drastically reduce the effort to break WEP encryption. Please note that this is true only for cases in which you are not using one of the EAP authentication types but are using only static WEP keys.
Software Versions and Fixes:
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.
Obtaining Fixed Software:
Cisco is offering free software upgrades to remedy this vulnerability for all affected customers. Customers may only install and expect support for the feature sets they have purchased.
Customers with contracts should obtain upgraded software through their regular update channels. For most customers, this means that upgrades should be obtained through the Software Center on Cisco's worldwide website at http://www.cisco.com.
Customers whose Cisco products are provided or maintained through prior or existing agreement with third-party support organizations such as Cisco Partners, authorized resellers, or service providers should contact that support organization for assistance with the upgrade, which should be free of charge.
Customers who purchase direct from Cisco but who do not hold a Cisco service contract and customers who purchase through third-party vendors but are unsuccessful at obtaining fixed software through their point of sale should get their upgrades by contacting the Cisco Technical Assistance Center (TAC). TAC contacts are as follows.
* +1 800 553 2447 (toll free from within North America)
* +1 408 526 7209 (toll call from anywhere in the world)
* e-mail: tac[at]cisco.com
See http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml for additional TAC contact information, including special localized telephone numbers and instructions and e-mail addresses for use in various languages.
Please have your product serial number available and give the URL of this notice as evidence of your entitlement to a free upgrade. Free upgrades for non-contract customers must be requested through the TAC.
Please do not contact either "psirt[at]cisco.com" or "security-alert[at]cisco.com" for software upgrades.
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/warp/public/779/smbiz/wireless/wlan_security.shtml/. The papers there are regarding general wireless security and provide configuration examples.
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