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             AUSCERT External Security Bulletin Redistribution

           ESB-2004.0440 -- iDEFENSE Security Advisory 06.21.04
        GNU Radius SNMP Invalid OID Denial of Service Vulnerability
                               05 July 2004

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        AusCERT Security Bulletin Summary
        ---------------------------------

Product:                GNU Radius
Publisher:              iDEFENSE
Impact:                 Denial of Service
Access Required:        Remote
CVE Names:              CAN-2004-0576

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GNU Radius SNMP Invalid OID Denial of Service Vulnerability 

iDEFENSE Security Advisory 06.21.04
www.idefense.com/application/poi/display?id=110&type=vulnerabilities
June 21, 2004

I. BACKGROUND

Radius is a server for remote user authentication and accounting. More
information about Radius is available at
http://www.gnu.org/software/radius/radius.html

II. DESCRIPTION

Remote exploitation of a denial of service condition within GNU Radius
allows attackers to crash the service.

The problem specifically exists in the code for handling SNMP messages.
By supplying a malformed packet containing an invalid OID, such as -1,
it is possible to cause the server to shutdown, preventing further
requests from being handled. The Radius server must have been compiled
with the '-enable-snmp' option in order to be vulnerable.

III. ANALYSIS

Successful exploitation allows unauthenticated remote attackers to cause
the radius daemon (radiusd) to crash. This prevents legitimate users
from accessing systems reliant upon the affected radius server for
authentication.

IV. DETECTION

iDEFENSE has confirmed the existence of this vulnerability in GNU Radius
version 1.1. It is suspected that earlier versions are also
affected. Version 1.2 is not vulnerable.

V. WORKAROUNDS

Ingress filtering of UDP port 161 on all interfaces that should not be
receiving SNMP packets may lessen exposure to this vulnerability in
affected environments.

VI. VENDOR FIX

This issue has been fixed in GNU Radius version 1.2.

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2004-0576 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
security problems.

VIII. DISCLOSURE TIMELINE

02/26/04   Issue acquired by iDEFENSE
06/09/04   Initial vendor contact
06/09/04   iDEFENSE clients notified 
06/21/04   Public disclosure 

IX. CREDIT

The discoverer wishes to remain anonymous.

Get paid for vulnerability research
http://www.idefense.com/poi/teams/vcp.jsp

X. LEGAL NOTICES

Copyright (c) 2004 iDEFENSE, Inc.

Permission is granted for the redistribution of this alert
electronically. It may not be edited in any way without the express
written consent of iDEFENSE. If you wish to reprint the whole or any
part of this alert in any other medium other than electronically, please
email customerservice@idefense.com for permission.

Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
of the information constitutes acceptance for use in an AS IS condition.
There are no warranties with regard to this information. Neither the
author nor the publisher accepts any liability for any direct, indirect,
or consequential loss or damage arising from use of, or reliance on,
this information.

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