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CERT Coordination Center


KTH Kerberos filesystem race condition on tickets stored in /tmp

Vulnerability Note VU#426273

Original Release Date: 2000-12-19 | Last Revised: 2001-01-11

Overview

There may be a race condition during the creation of Kerberos ticket files in the /tmp directory. This race condition may allow intruders with local access to the system to gain root privileges.

Description

During the creation of ticket files in the /tmp directory, a sequence of calls occur which may allow a local attacker to replace the ticket file with a symbolic link. If this symbolic link is followed when the ownership of the ticket file is set, the attacker may be able to gain ownership of files initially owned by root.

Impact

On systems where the sticky bit is not set on the /tmp directory, a local attacker can gain ownership of any file on the system. This allows the attacker to gain root privileges.

This attack may also be possible on systems where the /tmp directory does have its sticky bit set, depending on the exact sequence of calls used to create and set the ownership of the Kerberos ticket file.

Solution

Apply a patch from your vendor.

Vendor Information

426273
Expand all

FreeBSD

Notified:  December 11, 2000 Updated:  December 14, 2000

Status

  Vulnerable

Vendor Statement

FreeBSD includes the externally maintained KTH Kerberos software as an optional component of the FreeBSD base system. Therefore, systems which have installed the Kerberos 4 components are vulnerable to these problems as described in the CERT advisory. Patches have been committed to the FreeBSD source tree and an advisory will be released shortly detailing the precise impact on vulnerable FreeBSD systems.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Apple

Notified:  December 11, 2000 Updated:  December 14, 2000

Status

  Not Vulnerable

Vendor Statement

Apple has conducted an investigation and determined that Mac OS X Public Beta does not use KTH Kerberos version 4 and is not susceptible to this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Compaq Computer Corporation

Notified:  December 11, 2000 Updated:  December 14, 2000

Status

  Not Vulnerable

Vendor Statement

Not vulnerable.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Fujitsu

Notified:  December 11, 2000 Updated:  January 11, 2001

Status

  Not Vulnerable

Vendor Statement

Fujitsu's UXP/V operating system is not vulnerable to the bugs in VU#602625, VU#759265, and VU#426273, because UXP/V does not support Kerberos.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

IBM

Notified:  December 11, 2000 Updated:  December 14, 2000

Status

  Not Vulnerable

Vendor Statement

Our AIX operating system does not include KTH Kerberos IV, so it is not vulnerable to the security exploits described here.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Microsoft

Notified:  December 11, 2000 Updated:  December 14, 2000

Status

  Not Vulnerable

Vendor Statement

Windows 2000 does not support Kerb IV. W2K does not use files to implement the ticket cache, and is not vulnerable to the race condition identified by VU#426273.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

BSDI

Notified:  December 11, 2000 Updated:  December 14, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Caldera

Notified:  December 11, 2000 Updated:  December 14, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Data General

Notified:  December 11, 2000 Updated:  December 14, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Debian

Notified:  December 11, 2000 Updated:  December 14, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Hewlett Packard

Notified:  December 11, 2000 Updated:  December 14, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

KTH Kerberos

Updated:  December 14, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

NetBSD

Notified:  December 11, 2000 Updated:  December 14, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

OpenBSD

Notified:  December 11, 2000 Updated:  December 14, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

RedHat

Notified:  December 11, 2000 Updated:  December 14, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

SGI

Notified:  December 11, 2000 Updated:  December 14, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Sony

Notified:  December 11, 2000 Updated:  December 14, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Sun

Notified:  December 11, 2000 Updated:  December 14, 2000

Status

  Unknown

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Washington University

Notified:  December 11, 2000 Updated:  December 14, 2000

Status

  Unknown

Vendor Statement

WU-FTPD 2.6.1 supports Kerberos in one of two ways:

    • Via PAM: in which case we defer any statement of vulnerability to the PAM maintainers.
    • Via direct calls: in which case we are probably as vulnerable as any other service using Kerberos for user authentication.
    For WU-FTPD systems using Kerberos, especially those which do not use shared libraries, I would recommend re-compiling (specifically, re-linking) the daemon to ensure an updated Kerberos runtime is used.

    Vendor Information

    The vendor has not provided us with any further information regarding this vulnerability.

    Addendum

    The CERT/CC has no additional comments at this time.

    If you have feedback, comments, or additional information about this vulnerability, please send us email.


    CVSS Metrics

    Group Score Vector
    Base N/A N/A
    Temporal N/A N/A
    Environmental N/A

    References

    Credit

    Thanks to Jouko Pynnönen for reporting this vulnerability to the CERT/CC, and to Assar Westerlund for assisting in the development of this document.

    This document was written by Cory F Cohen.

    Other Information

    CVE IDs: None
    Severity Metric: 8.19
    Date Public: 2000-12-09
    Date First Published: 2000-12-19
    Date Last Updated: 2001-01-11 15:20 UTC
    Document Revision: 9

    Sponsored by the Department of Homeland Security Office of Cybersecurity and Communications.