AUSCERT External Security Bulletin Redistribution

                   ESB-2001.278 -- ISS Security Advisory
         Remote Buffer Overflow in Multiple RADIUS Implementations
                               10 July 2001


        AusCERT Security Bulletin Summary

Product:                Merit 3.6b RADIUS
                        Lucent 2.1-2 RADIUS
Vendor:                 Merit
Impact:                 Execute Arbitrary Code/Commands
                        Denial of Service
Access Required:        Remote

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Internet Security Systems Security Advisory
July 5, 2001

Remote Buffer Overflow in Multiple RADIUS Implementations


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. 


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.


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


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.


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
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e-mail xforce@iss.net for permission.


The information within this paper may change without notice. Use of
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There are NO warranties with regard to this information. In no event
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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
xforce@iss.net of Internet Security Systems, Inc.

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