Vulnerability Note VU#661243

MIT Kerberos V5 KDC vulnerable to denial-of-service via null pointer dereference

Overview

A vulnerability exists in MIT Kerberos V5 Key Distribution Center that may allow attackers to crash multiple KDC servers within the same realm.

I. Description

The MIT Kerberos V5 Key Distribution Center (KDC) contains a vulnerability that allows certain protocol requests to crash the KDC by triggering a null pointer dereference. Requests of this form are compliant with the Kerberos protocol, but unlikely to occur in properly configured clients. When this type of crash occurs, the client will attempt to contact other KDCs in the same realm, causing them to crash as well.

This vulnerability is believed to be limited TGS-REQ exchanges, which require the client to be authenticated. Therefore, to exploit this vulnerability, attackers must authenticate using a valid user name and password.

II. Impact

Authenticated attackers can crash one or more KDCs in a given realm.

III. Solution

This vulnerability was addressed in MIT Kerberos V5 1.2.5, released on April 30, 2002. MIT krb5 Security Advisory 2003-001 provides additional information from MIT and is available at:

http://web.mit.edu/kerberos/www/advisories/MITKRB5-SA-2003-001-multiple.txt

For information regarding other vendors who may be affected, please see the vendor section of this document.

Systems Affected

Vendor	Status	Date Notified
KTH Kerberos	Unknown	29-Jan-2003
MandrakeSoft	Vulnerable	4-Apr-2003
Microsoft Corporation	Not Vulnerable	31-Jan-2003
MIT Kerberos Development Team	Vulnerable	30-Jan-2003
Red Hat Inc.	Vulnerable	27-Mar-2003

References

http://web.mit.edu/kerberos/www/advisories/MITKRB5-SA-2003-001-multiple.txt
http://www.ietf.org/rfc/rfc1510.txt

Credit

The CERT/CC thanks Greg Pryzby for discovering this vulnerability and Ken Raeburn of MIT for bringing it to our attention.

This document was written by Jeffrey P. Lanza.

Other Information

Date Public:	2002-09-16
Date First Published:	2003-01-31
Date Last Updated:	2003-04-04
CERT Advisory:
CVE-ID(s):	CAN-2003-0058
NVD-ID(s):	CAN-2003-0058
US-CERT Technical Alerts:
Metric:	1.23
Document Revision:	30

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