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60 lines
2.1 KiB
Groff
60 lines
2.1 KiB
Groff
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.\" $Id$
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.\" Copyright 1989 by the Massachusetts Institute of Technology.
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.\"
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.\" For copying and distribution information,
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.\" please see the file <Copyright.MIT>.
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.\"
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.TH FIX_KDB_KEYS 8 "Kerberos Version 4.0" "MIT Project Athena"
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.SH NAME
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fix_kdb_keys \- Secure Kerberos database by properly randomising keys
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.SH SYNOPSIS
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fix_kdb_keys
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.SH DESCRIPTION
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If you built your Kerberos database before receiving this distribution,
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the keys were randomly generated using the vulnerable version of
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the Kerberos random number generator. Therefore it is possible for
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an attacker to mount an attack to guess these values. If an attacker
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can determine the key for the
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.I krbtgt
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ticket, they can construct tickets claiming to be any Kerberos
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principal. Similarly if an attacker can obtain the
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.I changepw.kerberos
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key, they can change anyone's password.
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.PP
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This distribution has been patched to use the improved
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.IR des_new_random_key()
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routines instead of the old and cryptographically suspect
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.IR des_random_key().
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.PP
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The primary difference is that
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.IR des_random_key()
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uses a seeding
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technique which is predictable and therefore vulnerable. While
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.IR des_new_random_key()
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uses a feedback mechanism based on the Data Encryption Standard
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(DES) and is seeded with a secret (and therefore unknown to an
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attacker) value. This value is the secret database master key.
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.PP
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Running
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.I fix_kdb_keys
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on the KDC server will change these critical keys to new
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values using the newer random number generator. IMPORTANT: When this
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is done, all outstanding ticket granting tickets will
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immediately become invalid. This will be disruptive to your user
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community. It is recommended that this is done late at night or early
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in the morning before most users have logged in. Alternatively
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pre-announce a definitive time when you will run the program and
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inform the users that they will have to get new tickets at that time
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(using either
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.I kinit
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or simply by logging out and then in again).
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.SH DIAGNOSTICS
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Many, and descriptive.
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.SH FILES
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.TP 20n
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/etc/kerberosIV/principal.db
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DBM file containing database
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.TP
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/etc/kerberosIV/master_key
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Master key cache file.
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