From 7f5e36250fa7121435f315cffa7b7059d3fe40a8 Mon Sep 17 00:00:00 2001 From: Stefan Metzmacher Date: Fri, 25 Nov 2022 14:02:11 +0100 Subject: [PATCH 21/30] CVE-2022-38023 docs-xml/smbdotconf: document "server reject md5 schannel:COMPUTERACCOUNT" BUG: https://bugzilla.samba.org/show_bug.cgi?id=15240 Signed-off-by: Stefan Metzmacher Reviewed-by: Andrew Bartlett Reviewed-by: Ralph Boehme (cherry picked from commit 2ad302b42254e3c2800aaf11669fe2e6d55fa8a1) Conflict: NA Reference: https://attachments.samba.org/attachment.cgi?id=17692 --- docs-xml/smbdotconf/logon/allownt4crypto.xml | 13 ++- .../smbdotconf/logon/rejectmd5clients.xml | 96 ++++++++++++++++++- 2 files changed, 103 insertions(+), 6 deletions(-) diff --git a/docs-xml/smbdotconf/logon/allownt4crypto.xml b/docs-xml/smbdotconf/logon/allownt4crypto.xml index bbd03a42db74..ee63e6cc2453 100644 --- a/docs-xml/smbdotconf/logon/allownt4crypto.xml +++ b/docs-xml/smbdotconf/logon/allownt4crypto.xml @@ -45,7 +45,9 @@ in order to collect the explicit 'yes' options. - This option is over-ridden by the 'yes' option. + This option is over-ridden by the effective value of 'yes' from + the '' + and/or '' options. no @@ -85,12 +87,19 @@ This option overrides the option. - This option is over-ridden by the 'yes' option. + This option is over-ridden by the effective value of 'yes' from + the '' + and/or '' options. + Which means 'yes' + is only useful in combination with 'no' allow nt4 crypto:LEGACYCOMPUTER1$ = yes + server reject md5 schannel:LEGACYCOMPUTER1$ = no allow nt4 crypto:NASBOX$ = yes + server reject md5 schannel:NASBOX$ = no allow nt4 crypto:LEGACYCOMPUTER2$ = yes + server reject md5 schannel:LEGACYCOMPUTER2$ = no diff --git a/docs-xml/smbdotconf/logon/rejectmd5clients.xml b/docs-xml/smbdotconf/logon/rejectmd5clients.xml index edcbe02e99a3..fe7701d92772 100644 --- a/docs-xml/smbdotconf/logon/rejectmd5clients.xml +++ b/docs-xml/smbdotconf/logon/rejectmd5clients.xml @@ -1,8 +1,15 @@ + + This option is deprecated and will be removed in a future release, + as it is a security problem if not set to "yes" (which will be + the hardcoded behavior in the future). + + This option controls whether the netlogon server (currently only in 'active directory domain controller' mode), will reject clients which does not support NETLOGON_NEG_SUPPORTS_AES. @@ -10,13 +17,94 @@ Support for NETLOGON_NEG_SUPPORTS_AES was added in Windows starting with Server 2008R2 and Windows 7, it's available in Samba starting with 4.0, however third party domain members like NetApp ONTAP - still uses RC4 (HMAC-MD5), see https://www.samba.org/samba/security/CVE-2022-38023.html for more details. + still uses RC4 (HMAC-MD5), see + https://www.samba.org/samba/security/CVE-2022-38023.html + for more details. + + + The default changed from 'no' to 'yes', with the patches for + CVE-2022-38023 + see https://bugzilla.samba.org/show_bug.cgi?id=15240. + + + Avoid using this option! Use an explicit per machine account + '' instead! + Which is available with the patches for + CVE-2022-38023 + see https://bugzilla.samba.org/show_bug.cgi?id=15240. + - The default changed from 'no' to 'yes', with the patches for CVE-2022-38023, - see https://bugzilla.samba.org/show_bug.cgi?id=15240 + + Samba will log an error in the log files at log level 0 + if legacy a client is rejected or allowed without an explicit, + 'no' option + for the client. The message will indicate + the explicit 'no' + line to be added, if the legacy client software requires it. (The log level can be adjusted with + '1' + in order to complain only at a higher log level). + - This option overrides the 'allow nt4 crypto' option. + This allows admins to use "no" only for a short grace period, + in order to collect the explicit + 'no' options. + + When set to 'yes' this option overrides the + '' and + '' options and implies + 'no'. + yes + + + + + If you still have legacy domain members or trusted domains, + which required "reject md5 clients = no" before, + it is possible to specify an explicit exception per computer account + by setting 'server reject md5 schannel:COMPUTERACCOUNT = no'. + Note that COMPUTERACCOUNT has to be the sAMAccountName value of + the computer account (including the trailing '$' sign). + + + + Samba will log a complaint in the log files at log level 0 + about the security problem if the option is set to "no", + but the related computer does not require it. + (The log level can be adjusted with + '1' + in order to complain only at a higher log level). + + + + Samba will log a warning in the log files at log level 5 + if a setting is still needed for the specified computer account. + + + + See CVE-2022-38023, + https://bugzilla.samba.org/show_bug.cgi?id=15240. + + + This option overrides the option. + + When set to 'yes' this option overrides the + '' and + '' options and implies + 'no'. + + + + server reject md5 schannel:LEGACYCOMPUTER1$ = no + server reject md5 schannel:NASBOX$ = no + server reject md5 schannel:LEGACYCOMPUTER2$ = no + + + + -- 2.34.1