GNU Radius SNMP Invalid OID Denial of Service Vulnerability

iDEFENSE Security Advisory 06.21.04:

*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 © 2004 iDEFENSE, Inc.

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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
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or consequential loss or damage arising from use of, or reliance on,
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