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From c1926dfc6591b55c4d33f9944de4d7ebe077e964 Mon Sep 17 00:00:00 2001 |
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From: Firstyear <william@blackhats.net.au> |
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Date: Fri, 9 Jul 2021 11:53:35 +1000 |
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Subject: [PATCH] Issue 4817 - BUG - locked crypt accounts on import may allow |
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all passwords (#4819) |
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|
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Bug Description: Due to mishanding of short dbpwd hashes, the |
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crypt_r algorithm was misused and was only comparing salts |
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in some cases, rather than checking the actual content |
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of the password. |
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|
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Fix Description: Stricter checks on dbpwd lengths to ensure |
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that content passed to crypt_r has at least 2 salt bytes and |
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1 hash byte, as well as stricter checks on ct_memcmp to ensure |
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that compared values are the same length, rather than potentially |
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allowing overruns/short comparisons. |
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fixes: https://github.com/389ds/389-ds-base/issues/4817 |
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Author: William Brown <william@blackhats.net.au> |
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Review by: @mreynolds389 |
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---
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.../password/pwd_crypt_asterisk_test.py | 50 +++++++++++++++++++ |
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ldap/servers/plugins/pwdstorage/crypt_pwd.c | 20 +++++--- |
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2 files changed, 64 insertions(+), 6 deletions(-) |
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create mode 100644 dirsrvtests/tests/suites/password/pwd_crypt_asterisk_test.py |
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diff --git a/dirsrvtests/tests/suites/password/pwd_crypt_asterisk_test.py b/dirsrvtests/tests/suites/password/pwd_crypt_asterisk_test.py
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new file mode 100644 |
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index 000000000..d76614db1
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--- /dev/null
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+++ b/dirsrvtests/tests/suites/password/pwd_crypt_asterisk_test.py
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@@ -0,0 +1,50 @@
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+# --- BEGIN COPYRIGHT BLOCK ---
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+# Copyright (C) 2021 William Brown <william@blackhats.net.au>
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+# All rights reserved.
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+#
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+# License: GPL (version 3 or any later version).
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+# See LICENSE for details.
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+# --- END COPYRIGHT BLOCK ---
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+#
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+import ldap
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+import pytest
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+from lib389.topologies import topology_st
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+from lib389.idm.user import UserAccounts
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+from lib389._constants import (DEFAULT_SUFFIX, PASSWORD)
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+
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+pytestmark = pytest.mark.tier1
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+
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+def test_password_crypt_asterisk_is_rejected(topology_st):
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+ """It was reported that {CRYPT}* was allowing all passwords to be
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+ valid in the bind process. This checks that we should be rejecting
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+ these as they should represent locked accounts. Similar, {CRYPT}!
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+
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+ :id: 0b8f1a6a-f3eb-4443-985e-da14d0939dc3
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+ :setup: Single instance
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+ :steps: 1. Set a password hash in with CRYPT and the content *
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+ 2. Test a bind
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+ 3. Set a password hash in with CRYPT and the content !
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+ 4. Test a bind
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+ :expectedresults:
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+ 1. Successfully set the values
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+ 2. The bind fails
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+ 3. Successfully set the values
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+ 4. The bind fails
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+ """
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+ topology_st.standalone.config.set('nsslapd-allow-hashed-passwords', 'on')
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+ topology_st.standalone.config.set('nsslapd-enable-upgrade-hash', 'off')
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+
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+ users = UserAccounts(topology_st.standalone, DEFAULT_SUFFIX)
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+ user = users.create_test_user()
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+
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+ user.set('userPassword', "{CRYPT}*")
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+
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+ # Attempt to bind with incorrect password.
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+ with pytest.raises(ldap.INVALID_CREDENTIALS):
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+ badconn = user.bind('badpassword')
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+
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+ user.set('userPassword', "{CRYPT}!")
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+ # Attempt to bind with incorrect password.
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+ with pytest.raises(ldap.INVALID_CREDENTIALS):
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+ badconn = user.bind('badpassword')
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+
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diff --git a/ldap/servers/plugins/pwdstorage/crypt_pwd.c b/ldap/servers/plugins/pwdstorage/crypt_pwd.c
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index 9031b2199..1b37d41ed 100644
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--- a/ldap/servers/plugins/pwdstorage/crypt_pwd.c
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+++ b/ldap/servers/plugins/pwdstorage/crypt_pwd.c
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@@ -48,15 +48,23 @@ static unsigned char itoa64[] = /* 0 ... 63 => ascii - 64 */
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int |
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crypt_pw_cmp(const char *userpwd, const char *dbpwd) |
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{ |
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- int rc;
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- char *cp;
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+ int rc = -1;
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+ char *cp = NULL;
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+ size_t dbpwd_len = strlen(dbpwd);
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struct crypt_data data; |
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data.initialized = 0; |
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- /* we use salt (first 2 chars) of encoded password in call to crypt_r() */
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- cp = crypt_r(userpwd, dbpwd, &data);
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- if (cp) {
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- rc = slapi_ct_memcmp(dbpwd, cp, strlen(dbpwd));
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+ /*
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+ * there MUST be at least 2 chars of salt and some pw bytes, else this is INVALID and will
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+ * allow any password to bind as we then only compare SALTS.
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+ */
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+ if (dbpwd_len >= 3) {
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+ /* we use salt (first 2 chars) of encoded password in call to crypt_r() */
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+ cp = crypt_r(userpwd, dbpwd, &data);
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+ }
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+ /* If these are not the same length, we can not proceed safely with memcmp. */
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+ if (cp && dbpwd_len == strlen(cp)) {
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+ rc = slapi_ct_memcmp(dbpwd, cp, dbpwd_len);
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} else { |
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rc = -1; |
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} |
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