Internet Security Systems Security Advisory June 20, 2001 Wired-side SNMP WEP key exposure in 802.11b Access Points Synopsis: Internet Security Systems (ISS) X-Force has discovered a vulnerability in several 802.11b Access Point devices. This problem may reveal the Wired Equivalent Privacy (WEP) key that is associated with the wired network. The WEP key is part of an encryption technique that provides secure data transmissions between wireless Access Points and PCs. The WEP encryption key can be obtained via a Simple Network Management Protocol (SNMP) query sent to the Access Point from a computer on the wired network. It is possible for an attacker to gain access to the WEP encryption key from the wired side, and then decrypt traffic on the wireless network. This attack is only possible if the Access Point is attacked from a wired network. Affected Products and Releases: X-Force confirmed the following products are vulnerable: 3Com AirConnect Model Number AP-4111 Symbol 41X1 Access Point Series Symbol Technologies Inc. provides 802.11b Access Point technology to several vendors under Original Equipment Manufacturer (OEM) agreements. These devices are branded and sold as distinct products. ISS X-Force has not tested all potentially vulnerable products. ISS X-Force recommends referring to the following URL for information about additional potentially vulnerable devices: http://www.symbol.com/products/wireless/wireless_alliances_and_partner.html Description: The WEP encryption key is used to provide wireless clients with confidentiality and authentication in an IEEE 802.11b (a standard for wireless transmissions) environment. The IEEE 802.11b standard Management Information Base (MIB) includes the definition for dot11WEPDefaultKeyValue in the dot11WEPDefaultKeysTable, and explicitly states that, "The WEP default secret keys are logically WRITE-ONLY. Attempts to read the entries in this table shall return unsuccessful status and values of null or zero." All affected Access Points support the IEEE 802.11b MIB and the vendor-specific MIB. The Symbol SNMP agent reveals the WEP encryption key in response to a valid wired-side SNMP query for the following: 1. IEEE 802.11b MIB: dot11WEPDefaultKeyValue in the dot11WEPDefaultKeysTable 2. Symbol MIB: ap128bWepKeyValue in the ap128bWEPKeyTable The current implementation of the Symbol SNMP agent presents a standard compliance issue. More importantly, the privacy of wireless clients may not be protected, and as a result, the authentication mechanism may not be reliable. Recommendations: Symbol Technologies has made a firmware update available to address the problems documented in this advisory. Contact your vendor for information about this update and its availability. 3Com Corporation will make the firmware update available on their Web site: http://www.3Com.com This vulnerability is closely related to how manufacturers comply with IEEE 802.11b standards. It is possible that additional Access Points from other vendors may be vulnerable to the problems described in this advisory. ISS X-Force recommends that all Access Point users check for the existence of this vulnerability. ISS RealSecure and ISS Internet Scanner have been upgraded with the most comprehensive 802.11b wireless vulnerability and threat detection available. The upcoming Wireless X-Press Updates will provide extensive coverage for major security issues found in many popular Access Points. ISS X-Force recommends upgrading to the latest X-Press Updates when they become available. ISS Consulting and Managed Security Services (MSS) can provide a variety of wireless security offerings including security health checks, wireless security policy, wireless architecture design, and managed wireless network protection. ISS SecureU is offering educational courses on 802.11 wireless security. Please refer to the following URL for more information: http://www.iss.net/wireless Additional Information: The Common Vulnerabilities and Exposures (CVE) project has assigned the Name CAN-2001-0352 to this issue. This is a candidate for inclusion in the CVE list http://cve.mitre.org, which standardizes names for security problems. Credits: This vulnerability was discovered and researched by Kevin Chou of the ISS X-Force. Internet Security Systems would like to thank Symbol Technologies and 3Com Corporation for their response and handling of this vulnerability. ______ About Internet Security Systems (ISS) Internet Security Systems is the leading global provider of security management solutions for the Internet, protecting digital assets and ensuring safe and uninterrupted e-business. With its industry-leading intrusion detection and vulnerability assessment, remote managed security services, and strategic consulting and education offerings, ISS is a trusted security provider to more than 8,000 customers worldwide including 21 of the 25 largest U.S. commercial banks and the top 10 U.S. telecommunications companies. Founded in 1994, ISS is headquartered in Atlanta, GA, with additional offices throughout North America and international operations in Asia, Australia, Europe, Latin America and the Middle East. For more information, visit the Internet Security Systems web site at www.iss.net or call 888-901-7477. Copyright (c) 2001 Internet Security Systems, Inc. Permission is hereby granted for the redistribution of this Alert electronically. It is not to be edited in any way without express consent of the X-Force. If you wish to reprint the whole or any part of this Alert in any other medium excluding electronic medium, please e-mail xforceat_private for permission. Disclaimer The information within this paper may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties with regard to this information. In no event shall the author be liable for any damages whatsoever arising out of or in connection with the use or spread of this information. Any use of this information is at the user's own risk. X-Force PGP Key available at: http://xforce.iss.net/sensitive.php as well as on MIT's PGP key server and PGP.com's key server. Please send suggestions, updates, and comments to: X-Force xforceat_private of Internet Security Systems, Inc.
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