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AUSCERT External Security Bulletin Redistribution
ESB-2004.0406 -- Sun Alert Notification - Sun Alert ID: 57580
Solaris/SEAM Kerberos 5 Vulnerability Due To Buffer Overflows In
krb5_aname_to_localname()
15 June 2004
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AusCERT Security Bulletin Summary
---------------------------------
Product: Kerberos 5
Publisher: Sun Microsystems
Operating System: Solaris 8
Solaris 9
SEAM 1.0 (for Solaris 7)
SEAM 1.0.1 (for Solaris 8)
SEAM 1.0.2 (for Solaris 9)
Impact: Root Compromise
Access Required: Existing Account
Ref: ESB-2004.0378
Comment: Original Bulletin:
http://sunsolve.sun.com/pub-cgi/retrieve.pl?doc=fsalert%2F57580
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DOCUMENT ID: 57580
SYNOPSIS: Solaris/SEAM Kerberos 5 Vulnerability Due To Buffer
Overflows In krb5_aname_to_localname()
DETAIL DESCRIPTION:
Sun(sm) Alert Notification
* Sun Alert ID: 57580
* Synopsis: Solaris/SEAM Kerberos 5 Vulnerability Due To Buffer
Overflows In krb5_aname_to_localname()
* Category: Security
* Product: Solaris, Solaris Enterprise Authentication Mechanism
(SEAM)
* BugIDs: 5055875
* Avoidance: Workaround
* State: Committed
* Date Released: 10-Jun-2004
* Date Closed:
* Date Modified:
1. Impact
On Kerberos 5 enabled systems using auth_to_local mapping through
appropriate entries in the krb5 configuration file krb5.conf(4); an
unprivileged local or remote user with kerberos credentials may be
able to execute arbitrary code with root privileges due to buffer
overflows in krb5_aname_to_localname() function.
This issue is described in CERT vulnerability VU#686862 at
[1]http://www.kb.cert.org/vuls/id/686862 and MIT krb5 Security
Advisory 2004-001 at
[2]http://web.mit.edu/kerberos/advisories/MITKRB5-SA-2004-001-an_to_ln
.txt.
2. Contributing Factors
This issue can occur in the following releases:
SPARC Platform
* Solaris 8
* Solaris 9
* SEAM 1.0 (for Solaris 7)
* SEAM 1.0.1 (for Solaris 8)
* SEAM 1.0.2 (for Solaris 9)
x86 Platform
* Solaris 8
* Solaris 9
* SEAM 1.0 (for Solaris 7)
* SEAM 1.0.1 (for Solaris 8)
* SEAM 1.0.2 (for Solaris 9)
Note: Solaris Enterprise Authentication Mechanism (SEAM) is an
unbundled product available for Solaris 7, 8 and 9. For more
information on SEAM, please see the SEAM(5) man page.
For Solaris without SEAM, this issue may only occur if the system is
configured to be a Kerberos client, verified by running the following
command:
% grep default_realm /etc/krb5/krb5.conf | grep -v __default_realm__default
_realm = EXAMPLE.COM
If the command returns no output or the krb5.conf(4) file is not
found, then the system is not configured for Kerberos.
In addition, systems are only vulnerable to this issue if they have
been configured to enable the "explicit" mapping or "rules-based"
mapping of the principal mapping functionality. This is not the
default configuration. A system which is vulnerable will have one of
the following entries in the krb5 configuration file (see
krb5.conf(4)):
The explicit mapping form is similar to:
auth_to_local_names = {
aname = lname
}
The rule-based mapping form is similar to:
auth_to_local = RULE:foo
3. Symptoms
There are no predictable symptoms that would indicate the described
issue has been exploited.
SOLUTION SUMMARY:
4. Relief/Workaround
To work around the described issue, disable the "auth_to_local" rules
by commenting out the code for "auth_to_local" from the
"/etc/krb5/krb5.conf" configuration file.
5. Resolution
A final resolution is pending completion.
This Sun Alert notification is being provided to you on an "AS IS"
basis. This Sun Alert notification may contain information provided by
third parties. The issues described in this Sun Alert notification may
or may not impact your system(s). Sun makes no representations,
warranties, or guarantees as to the information contained herein. ANY
AND ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION
WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR
NON-INFRINGEMENT, ARE HEREBY DISCLAIMED. BY ACCESSING THIS DOCUMENT
YOU ACKNOWLEDGE THAT SUN SHALL IN NO EVENT BE LIABLE FOR ANY DIRECT,
INDIRECT, INCIDENTAL, PUNITIVE, OR CONSEQUENTIAL DAMAGES THAT ARISE
OUT OF YOUR USE OR FAILURE TO USE THE INFORMATION CONTAINED HEREIN.
This Sun Alert notification contains Sun proprietary and confidential
information. It is being provided to you pursuant to the provisions of
your agreement to purchase services from Sun, or, if you do not have
such an agreement, the Sun.com Terms of Use. This Sun Alert
notification may only be used for the purposes contemplated by these
agreements.
Copyright 2000-2004 Sun Microsystems, Inc., 4150 Network Circle, Santa
Clara, CA 95054 U.S.A. All rights reserved.
References
1. http://www.kb.cert.org/vuls/id/686862
2. http://web.mit.edu/kerberos/advisories/MITKRB5-SA-2004-001-an_to_ln.txt
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