GNU Radius Format String Vulnerability

iDefense Security Advisory 11.26.06
http://labs.idefense.com/intelligence/vulnerabilities/ 
Nov 26, 2006

I. BACKGROUND

GNU Radius is a centralized user authentication and accounting system. It
supports back-end SQL databases for accounting. More information can be
found at http://www.gnu.org/software/radius/ 

II. DESCRIPTION

Remote exploitation of a format string vulnerability in GNU Radius could
allow an attacker to execute code in the context of the running daemon.

The vulnerability specifically exists within the SQL accounting code. A
format string is built using user supplied data and then unsafely passed
to the variable argument function 'sqllog'.

III. ANALYSIS

Successful exploitation allows unauthenticated remote attackers to execute
arbitrary code in the context of the running radius daemon (radiusd).
Typically the radius daemon will run as root.

Exploitation requires that radiusd be compiled with an SQL back-end and
SQL accounting be turned on. These options are both turned on by default
for FreeBSD and Gentoo Linux.

IV. DETECTION

iDefense has confirmed that this vulnerability is present in version 1.3
and 1.2 of GNU Radius. It is likely that all prior versions are
vulnerable.

V. WORKAROUND

iDefense confirms that using one of the other supported accounting methods
will mitigate exploitation of this vulnerability while still allowing
accounting to take place.

VI. VENDOR RESPONSE

The GNU Radius team included a fix for this vulnerability in version 1.4.

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2006-4181 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

08/16/2006  Initial vendor notification
09/08/2006  Initial vendor response
11/06/2006  Second vendor notification
11/26/2006  Coordinated public disclosure

IX. CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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X. LEGAL NOTICES

Copyright =A9 2006 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
author nor the publisher accepts any liability for any direct, indirect,
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information.