Cisco Security Advisory: Multiple Vulnerabilities in the Cisco Wireless LAN Controller and Cisco Lightweight Access Points

Contents

Summary
Affected Products
Details
Impact
Software Versions and Fixes
Workarounds
Obtaining Fixed Software
Exploitation and Public Announcements
Status of This Notice: FINAL
Distribution
Revision History
Cisco Security Procedures

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Vulnerable Products

Products Confirmed Not Vulnerable

The Cisco Wireless LAN Controller (WLC) manages Cisco Aironet access points using the Lightweight Access Point Protocol (LWAPP). This protocol provides centralized management of wireless networks. The WLC contains the following vulnerabilities:

Default SNMP Community Strings

The WLC uses the commonly known values of "public" and "private" for its read-only and read-write SNMP community strings. This vulnerability is documented by Cisco Bug ID CSCse02384 ( registered customers only) .

Malformed Ethernet Traffic Crash

The WLC may crash in response to malformed Ethernet traffic. This vulnerability is documented by Cisco Bug ID CSCsc90179 ( registered customers only) .

Multiple NPU Lock-Up Vulnerabilities

The Network Processing Unit (NPU) is responsible for handling traffic within the WLC. It is possible to cause one or more NPUs to lock up by sending certain types of traffic to an affected WLC. This traffic includes crafted SNAP packets, malformed 802.11 traffic, and packets with unexpected length values in certain headers.

Each NPU operates independently and serves two of the physical ports on the WLC. A lock up in one NPU does not affect the others, so the number of NPUs available and the configuration of the device determine whether these vulnerabilities result in a partial or complete inability to forward traffic. To clear a NPU lock up, the WLC must be restarted. If the lock up condition prevents access to the management interface, the restart must be performed via the console port or service port.

Devices that implement the WLC functionality in software rather than hardware do not contain a NPU and are not affected by these vulnerabilities. These software-based devices are the 2000 Series WLC, the 2100 Series WLC, and the Cisco Wireless LAN Controller Module.

These vulnerabilities are documented by Cisco Bug IDs CSCsg36361 ( registered customers only) , CSCsg15901 ( registered customers only) , and CSCsh10841 ( registered customers only) .

Hard-Coded Service Password in Lightweight AP

The Cisco Aironet 1000 Series and 1500 Series Lightweight Access Points contain a hard-coded service password that is used for troubleshooting. This service account is only accessible via a physical connection to the console port, but the password is common to all units in these series. This vulnerability is documented by Cisco Bug ID CSCsg15192 ( registered customers only) .

WLAN ACL Does Not Persist Through Reboot

Version 4.0 of the WLC contains a bug when processing WLAN ACLs that causes the WLAN ACL configuration to be saved with an invalid checksum. This bug does not affect 3.2 versions of the WLC. When the configuration is subsequently reloaded at boot time, the checksum fails and the WLAN ACLs are not installed. This vulnerability is documented by Cisco Bug ID CSCse58195 ( registered customers only) .

Vulnerability Scoring Details

Cisco is providing scores for the vulnerabilities in this advisory based on the Common Vulnerability Scoring System (CVSS).

Cisco will provide a base and temporal score. Customers can then compute environmental scores to assist in determining the impact of the vulnerability in individual networks.

Cisco PSIRT will set the bias in all cases to normal. Customers are encouraged to apply the bias parameter when determining the environmental impact of a particular vulnerability.

CVSS is a standards based scoring method that conveys vulnerability severity and helps determine urgency and priority of response.

Cisco has provided an FAQ to answer additional questions regarding CVSS at http://www.cisco.com/web/about/security/intelligence/cvss-qandas.html.

Cisco has also provided a CVSS calculator to help compute the environmental impact for individual networks at http://intellishield.cisco.com/security/alertmanager/cvss.

CSCse02384 ( registered customers only) Calculate the environmental score of CSCse02384
CVSS Base Score - 10
Access Vector	Access Complexity	Authentication	Confidentiality Impact	Integrity Impact	Availability Impact	Impact Bias
Remote	Low	Not Required	Complete	Complete	Complete	Normal
CVSS Temporal Score - 8.3
Exploitability		Remediation Level		Report Confidence
Functional		Official Fix		Confirmed

CSCsc90179 ( registered customers only) Calculate the environmental score of CSCsc90179
CVSS Base Score - 3.3
Access Vector	Access Complexity	Authentication	Confidentiality Impact	Integrity Impact	Availability Impact	Impact Bias
Remote	Low	Not Required	None	None	Complete	Normal
CVSS Temporal Score - 2.7
Exploitability		Remediation Level		Report Confidence
Functional		Official Fix		Confirmed

CSCsg36361 ( registered customers only) Calculate the environmental score of CSCsg36361
CVSS Base Score - 3.3
Access Vector	Access Complexity	Authentication	Confidentiality Impact	Integrity Impact	Availability Impact	Impact Bias
Remote	Low	Not Required	None	None	Complete	Normal
CVSS Temporal Score - 2.7
Exploitability		Remediation Level		Report Confidence
Functional		Official Fix		Confirmed

CSCsg15901 ( registered customers only) Calculate the environmental score of CSCsg15901
CVSS Base Score - 3.3
Access Vector	Access Complexity	Authentication	Confidentiality Impact	Integrity Impact	Availability Impact	Impact Bias
Remote	Low	Not Required	None	None	Complete	Normal
CVSS Temporal Score - 2.7
Exploitability		Remediation Level		Report Confidence
Functional		Official Fix		Confirmed

CSCsh10841 ( registered customers only) Calculate the environmental score of CSCsh10841
CVSS Base Score - 3.3
Access Vector	Access Complexity	Authentication	Confidentiality Impact	Integrity Impact	Availability Impact	Impact Bias
Remote	Low	Not Required	None	None	Complete	Normal
CVSS Temporal Score - 2.7
Exploitability		Remediation Level		Report Confidence
Functional		Official Fix		Confirmed

CSCsg15192 ( registered customers only) Calculate the environmental score of CSCsg15192
CVSS Base Score - 5.6
Access Vector	Access Complexity	Authentication	Confidentiality Impact	Integrity Impact	Availability Impact	Impact Bias
Local	High	Not Required	Complete	Complete	Complete	Normal
CVSS Temporal Score - 4.6
Exploitability		Remediation Level		Report Confidence
Functional		Official Fix		Confirmed

CSCse58195 ( registered customers only) Calculate the environmental score of CSCse58195
CVSS Base Score - 3.7
Access Vector	Access Complexity	Authentication	Confidentiality Impact	Integrity Impact	Availability Impact	Impact Bias
Remote	High	Not Required	Partial	Partial	None	Normal
CVSS Temporal Score - 3.1
Exploitability		Remediation Level		Report Confidence
Functional		Official Fix		Confirmed

Successful exploitation of these vulnerabilities may result in the issues described in this section.

Default SNMP Community Strings

CSCse02384: This vulnerability allows authenticated, remote attackers to utilize common credentials to read and modify the configuration of the WLC via SNMP.

Malformed Ethernet Traffic Crash

CSCsc90179: This vulnerability may allow unauthenticated attackers on a local network segment to crash the WLC, resulting in a DoS condition.

Multiple NPU Lock-Up Vulnerabilities

CSCsg36361: This vulnerability allows unauthenticated attackers on a local wireless network segment to prevent the WLC from passing traffic, resulting in either a partial or complete DoS condition.

CSCsg15901: This vulnerability allows unauthenticated attackers on a local wireless network segment to prevent the WLC from passing traffic, resulting in either a partial or complete DoS condition.

CSCsh10841: This vulnerability allows unauthenticated attackers on a local wireless network segment to prevent the WLC from passing traffic, resulting in either a partial or complete DoS condition.

Hard-Coded Service Password in Lightweight AP

CSCsg15192: This vulnerability allows an attacker with physical access to take control of an affected lightweight access point.

WLAN ACL Does Not Persist Through Reboot

CSCse58195: This vulnerability causes the WLAN ACL configuration to be disregarded, resulting in a silent and unexpected change to the security posture of a wireless network.

When considering software upgrades, also consult http://www.cisco.com/go/psirt and any subsequent advisories to determine exposure and a complete upgrade solution.

In all cases, customers should exercise caution to be certain the devices to be upgraded contain sufficient memory and that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, contact the Cisco Technical Assistance Center ("TAC") or your contracted maintenance provider for assistance.

Each row of the software table (below) describes the earliest software version that contains the fix (the "First Fixed Release") and the anticipated date of availability when fixes are not available. A device running a version that is earlier than the First Fixed Release is known to be vulnerable. The release should be upgraded at least to the indicated version (greater than or equal to the First Fixed Release label).

Cisco Bug ID	First Fixed Releases
CSCse02384	4.1.171.0
CSCsc90179	3.2.116.21, 4.0.155.0
CSCsg36361	3.2.193.5, 4.0.206.0, 4.1.171.0
CSCsg15901	3.2.171.5, 4.0.206.0, 4.1.171.0
CSCsh10841	3.2.171.5, 4.0.206.0, 4.1.171.0
CSCsg15192	3.2.185.0, 4.0.206.0
CSCse58195	4.0.206.0

This section describes workarounds for these vulnerabilities.

Default SNMP Community Strings

Customers can mitigate this vulnerability by changing the SNMP community strings from their default values. This can be accomplished on each WLC by using the menu to access Management > SNMP > Communities and then changing the values of the community strings. On larger networks, the Cisco Wireless Control System can be used to apply SNMP changes across multiple controllers simultaneously.

Malformed Ethernet Traffic Crash

There are no known workarounds for this vulnerability.

Multiple NPU Lock-Up Vulnerabilities

There are no known workarounds for these vulnerabilities.

Hard-Coded Service Password in Lightweight AP

There are no known workarounds for this vulnerability.

WLAN ACL Does Not Persist Through Reboot

There are no known workarounds for this vulnerability.

Additional Workarounds

Additional mitigations that can be deployed on Cisco devices within the network are available in the Cisco Applied Mitigation Bulletin companion document for this advisory: http://www.cisco.com/warp/public/707/cisco-amb-20070412-wlc.shtml

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 http://www.cisco.com/public/sw-license-agreement.html, or as otherwise set forth at Cisco.com Downloads at http://www.cisco.com/public/sw-center/sw-usingswc.shtml.

Do not contact either "psirt@cisco.com" or "security-alert@cisco.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 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 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 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@cisco.com
  

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.

Refer to 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.

The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerabilities described in this advisory.

These vulnerabilities were discovered via internal testing and during the investigation of customer support cases.

THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.

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 is posted on Cisco's worldwide website at http://www.cisco.com/warp/public/707/cisco-sa-20070412-wlc.shtml.

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.

• cust-security-announce@cisco.com
  
• first-teams@first.org
  
• bugtraq@securityfocus.com
  
• vulnwatch@vulnwatch.org
  
• cisco@spot.colorado.edu
  
• cisco-nsp@puck.nether.net
  
• full-disclosure@lists.grok.org.uk
  
• comp.dcom.sys.cisco@newsgate.cisco.com
  

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.

Revision 1.4	2008-April-24	Updated links to the CVSS scoring for each bug ID.
Revision 1.3	2007-May-16	Updated First Fixed Releases information to include the recent 4.1 software release.
Revision 1.2	2007-April-16	Added additional products to the Wireless LAN Controller affected products and added information to the WLAN ACL Does Not Persist Through Reboot section.
Revision 1.1	2007-April-14	Minor grammatical changes.
Revision 1.0	2007-April-12	Initial public release.

Complete information on reporting security vulnerabilities in Cisco products, obtaining assistance with security incidents, and registering to receive security information from Cisco, is available on Cisco's worldwide website at http://www.cisco.com/en/US/products/products_security_vulnerability_policy.html. This includes instructions for press inquiries regarding Cisco security notices. All Cisco security advisories are available at http://www.cisco.com/go/psirt.