Advisory ID: cisco-sa-20031202-SNMP-trap
For Public Release 2003 December 2 17:00 UTC (GMT)
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
This section provides details on 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
If you are not presented with a menu in a graphic form but simply with
a prompt (such as ap1200%), then you may be
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
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.
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
No other Cisco products are currently known to be affected by these
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
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
registered customers only)
Cisco has provided scores for the vulnerabilities in this advisory based on the Common Vulnerability Scoring System (CVSS). The CVSS scoring in this Security Advisory is done in accordance with CVSS version 2.0.
CVSS is a standards-based scoring method that conveys vulnerability severity and helps determine urgency and priority of response.
Cisco has provided a base and temporal score. Customers can then compute environmental scores to assist in determining the impact of the vulnerability in individual networks.
Cisco has provided an FAQ to answer additional questions regarding CVSS at
Cisco has also provided a CVSS calculator to help compute the environmental impact for individual networks at
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.
The vulnerable Cisco IOS software releases are 12.2(8)JA, 12.2(11)JA
The first fixed release is 12.2(13)JA1.
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
The papers there are regarding general wireless security and provide
Cisco has made free software available to address this vulnerability
for affected customers. Prior to deploying software, customers should consult
their maintenance provider or check the software for feature set compatibility
and known issues specific to their environment.
Customers may only install and expect support for the feature sets they
have purchased. By installing, downloading, accessing or otherwise using such
software upgrades, customers agree to be bound by the terms of Cisco's software
license terms found at
or as otherwise set forth at Cisco.com Downloads at
Do not contact either "firstname.lastname@example.org" or "email@example.com"
for software upgrades.
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
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 guidance and assistance with the appropriate course of
action in regards to this advisory.
The effectiveness of any workaround or fix is dependent on specific
customer situations such as product mix, network topology, traffic behavior,
and organizational mission. Due to the variety of affected products and
releases, customers should consult with their service provider or support
organization to ensure any applied workaround or fix is the most appropriate
for use in the intended network before it is deployed.
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 in obtaining fixed software through their point of sale should obtain software patches and bug fixes 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)
Have your product serial number available and provide the URL of this notice as evidence of entitlement to a software patch or bug fix. Customers without service contracts should request a software patch or bug fix through the TAC.
for additional TAC contact information, including special localized telephone
numbers and instructions and e-mail addresses for use in various
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.
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A stand-alone copy or Paraphrase of the text of this document that omits the distribution URL in the following section is an uncontrolled copy, and may lack important information or contain factual errors.
This advisory will be posted on Cisco's worldwide website at
In addition to worldwide web posting, a text version of this notice is
clear-signed with the Cisco PSIRT PGP key and is posted to the following e-mail
and Usenet news recipients.
firstname.lastname@example.org (includes CERT/CC)
Various internal Cisco mailing
Future updates of this advisory, if any, will be placed on Cisco's
worldwide website, but may or may not be actively announced on mailing lists or
newsgroups. Users concerned about this problem are encouraged to check the
above URL for any updates.
Initial public release.