ISS: Remote Buffer Overflow in Multiple RADIUS Implementations

 Internet Security Systems Security Advisory July 5, 2001  Remote Buffer Overflow in Multiple RADIUS Implementations  Synopsis:  ISS X-Force has discovered buffer overflow vulnerabilities in two popular Remote Authentication Dial-In User Server (RADIUS) implementations. RADIUS was originally designed to manage user authentication into dial-up terminal servers and similar devices. It has since been used as a standard for access control and user  authentication for numerous Internet infrastructure devices, including routers, switches, and 802.11 Wireless Access Points.   Impact:  RADIUS is typically implemented as a "secure" access-control solution for critical network components. RADIUS is also implemented as a supplement to weak security measures provided in 802.11b specifications. The vulnerabilities described in this advisory may allow attackers to launch Denial of Service (DoS) attacks against critical network components, bypass 802.11 WLAN access control, or compromise and control protected network resources.  Affected Versions:  Merit 3.6b RADIUS Lucent 2.1-2 RADIUS  Earlier versions of both RADIUS distributions may also be affected.  Description:  RADIUS is a client-server internetworking security system. It controls authentication, accounting, and access-control in a networked, multi-user environment.  It is used primarily for authentication and access control management by wired Internet Service Providers (ISPs), wireless 802.11 MAC address authentication, large corporations, and educational institutions that manage large dial-in modem pools.  Multiple buffer overflow vulnerabilities exist in the authentication routines of various RADIUS implementations. These routines require user-supplied information. Adequate bounds checking measures are not taken when parsing user-supplied strings. Generally, the "radiusd" daemon (the RADIUS listener) runs with super user privilege. Attackers may use knowledge of these vulnerabilities to launch a Denial of Service (DoS) attack against the RADIUS server or execute arbitrary code on the RADIUS server. If an attacker can gain control of the RADIUS server, he may have the ability to control access to all networked devices served by RADIUS, as well as gather login and password information for these devices.  Recommendations:  ISS X-Force recommends that all network administrators using Lucent or Merit RADIUS upgrade to the new versions immediately.  Merit has identified and addressed the vulnerability. ISS X-Force recommends that all Merit 3.6B users upgrade to version 3.6B1. This patched distribution is available at the following address:    Lucent RADIUS is no longer maintained by Lucent. The Lucent RADIUS package is maintained by Simon Horms of VA Linux Systems. ISS X-Force worked with VA Linux Systems to develop and test patches for the vulnerabilities described in this advisory.  Patches will be available soon after the publication of this advisory at the following address:    ISS X-Force will provide detection and assessment support for this vulnerability in upcoming X-Press Updates for RealSecure Network Sensor and Internet Scanner.  Additional Information:  The Common Vulnerabilities and Exposures (CVE) project has assigned the name CAN-2001-0534 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org), which standardizes names for security problems.   ISS Consulting can offer security assessments and penetration testing for your organization. ISS Managed Security Services can also provide automated scanning and 24x7 IDS monitoring for these security issues. ISS SecureU offers educational courses on ISS products and detailed ethical hacking classes on these and other security issues.  Credits:  The vulnerabilities described in this advisory were primarily researched by Chris Spencer and Mark Dowd of the ISS X-Force. ISS X-Force would like to thank William Bulley of Merit and Simon Horms of VA Linux Systems. ______  About Internet Security Systems (ISS)  Internet Security Systems is a 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 xforce@iss.net 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:  as well as on MIT's PGP key server and PGP.com's key server.