Re: Event ID 538 Logon Type 3 NT AUTHORITY/ANONYMOUS LOGON
From: Steven L Umbach (n9rou_at_nospam-comcast.net)
Date: 03/18/05
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Date: Thu, 17 Mar 2005 22:00:34 -0600
The browser service is just one and the most common use of null sessions.
However disabling the browser service simply prevents the computer from
becoming a master browser or backup browser. If you can change the security
option for additional restrictions for anonymous access to be no access
without explicit anonymous permissions you will prevent null connections
though apparently you may still see anonymous logon events in the security
log as I experienced. The KB article below explains more on how to do this
but be sure to read the consequences first. --- Steve
http://support.microsoft.com/?kbid=246261
The following tasks are restricted when the RestrictAnonymous registry value
is set to 2 on a Windows 2000-based domain controller: . Down-level member
workstations or servers are not able to set up a netlogon secure channel.
. Down-level domain controllers in trusting domains are not be able to
set up a netlogon secure channel.
. Microsoft Windows NT users are not able to change their passwords
after they expire. Also, Macintosh users are not able to change their
passwords at all.
. The Browser service is not able to retrieve domain lists or server
lists from backup browsers, master browsers or domain master browsers that
are running on computers with the RestrictAnonymous registry value set to 2.
Because of this, any program that relies on the Browser service does not
function properly
"/.dz" <dz@discussions.microsoft.com> wrote in message
news:6D02852B-4580-422D-A4F1-81D7CC52C8FA@microsoft.com...
> Again, thanks. Here's what I know now that I didn't prior to your
> response --
> Your version of the 'null session' command has two less ""s in it. And
> that
> makes it work! So now I can indeed verify that I am able to establish a
> null
> session with my server; and 'yes' it apparently does log a 538 upon
> session
> termination. But allow me a further quesiton: Since I have the 'Computer
> Browser' service disabled on the server, why are 'null sessions' still
> allowed? I was under the impression that null sessions only existed to
> facilitate the 'enumeration' of resouces that the browsing capability
> supports; and therefore by disabling the Computer Browser service I would
> effectively prevent 'null sessions' from occurring. ??
>
> "Steven L Umbach" wrote:
>
>> I am experiencing something different than you are [ as shown below]. As
>> long as the security option for additional restrictions for anonymous
>> access
>> is NOT set to no access without explicit anonymous permissions I am able
>> to
>> create a null session. When I do have no access without explicit
>> anonymous
>> permissions enabled I can not create a null session and I simply get a
>> system error 5 has occurred - access is denied. Even when access was
>> denied
>> to my null session an Event ID 538 is recorded in the security log of my
>> server for successful anonymous logoff which indicates that these events
>> may
>> be recorded even if a null session is denied. You might want to see if
>> you
>> have any current sessons to your server before you try null session with
>> "
>> net use " command and delete them if there are any and try again. I doubt
>> Client for Microsoft Networks enabled on your server is causing the null
>> sessions to be created to your server. If your server does not need to
>> logon
>> to a domain or access shares/resources on other computers then you should
>> be
>> able to diable it with no ill effect. A dedicated web server for instance
>> would not need to use Client for Microsoft Networks. --- Steve
>>
>> D:\Documents and Settings\Steve>net use \\192.168.1.105\ipc$ "" /u:""
>> The command completed successfully.
>>
>>
>> D:\Documents and Settings\Steve>net use \\192.168.1.105\ipc$ "" /u:""
>> System error 5 has occurred.
>>
>> Access is denied.
>>
>> Event Type: Success Audit
>> Event Source: Security
>> Event Category: Logon/Logoff
>> Event ID: 538
>> Date: 3/16/2005
>> Time: 11:56:16 PM
>> User: NT AUTHORITY\ANONYMOUS LOGON
>> Computer: SERVER1-2000
>> Description:
>> User Logoff:
>> User Name: ANONYMOUS LOGON
>> Domain: NT AUTHORITY
>> Logon ID: (0x0,0x2CFBA3)
>> Logon Type: 3
>>
>>
>> "/.dz" <dz@discussions.microsoft.com> wrote in message
>> news:1D63D35D-431D-4A78-83BD-AE4A2E8EE0D1@microsoft.com...
>> > Steve:
>> > First thanks very much for the response. I've noticed that your name
>> > is
>> > on
>> > a lot of the responses in this forum and I appreciate the help as much
>> > as
>> > I'm
>> > sure the other people do as well.
>> >
>> > So anytime you get tired of this thread, it will probably die -- but I
>> > will
>> > continue to ask questions as long as you continue to respond.
>> >
>> > In your response, you mentioned 'null sessions'. In other articles
>> > I've
>> > read, there is a reference to using the statement [net use
>> > \\servername\ipc$
>> > """" /u:""] to check if null sessions are able to be created. When I
>> > attempted this statement from my workstation, targetting the
>> > 'servername'
>> > being discussed in this posting, I received the "Logon failure: unknown
>> > user
>> > name or bad password" message at the workstation, and the server logged
>> > an
>> > event 529 Logon failure, explicitly indicating my userid, workstation,
>> > and
>> > domain. From this info, I'm assuming that the 'null sessions'
>> > discussion
>> > does not apply to my situation. Is that a valid conclusion? Also, the
>> > Computer Browser service is disabled (and has been since installation)
>> > on
>> > the
>> > server. Am I also 'on-track' here in that these two items are directly
>> > related? (That is, 'null sessions' are enabled - i.e., required - for
>> > the
>> > Computer Browser service to function)
>> >
>> > I want to ask about the other items in your response as well, but to
>> > keep
>> > the dialog within reasonable bounds, I'm electing to go through it one
>> > item
>> > at a time --- starting (I think) with the most clearcut.
>> >
>> > Also in this thread, I need to about the 'Client for Microsoft
>> > Networks' .
>> > The server has this protocol enabled. Two further questions: a) This
>> > client
>> > is only necessary if the computer (the server in this case) wants to
>> > access
>> > other NETBIOS resources on the net; it is not required for other
>> > computers
>> > on
>> > the net to reach its (the server's) resources. Is this correct? b)
>> > the
>> > 'Client for Microsoft Networks' is not responsible for the 538 logout
>> > events
>> > mentioned in the original post?
>> >
>> > Any further dialog is greatly appreciated.
>> > ./dz
>> >
>> > "Steven L Umbach" wrote:
>> >
>> >> It is common to see those Events on computers using Windows networking
>> >> and
>> >> that have file and print sharing and Client for Microsoft networks
>> >> enabled.
>> >> Those often are null sessions used by the computer browser service.
>> >> While
>> >> null sessions can be used to enumerate users, groups, and shares you
>> >> can
>> >> mitigate the risk by using a firewall to prevent internet access to
>> >> null
>> >> sessions, enforcing strong passwords on your network, and making sure
>> >> your
>> >> share/folder permissions only allow authorized users access.
>> >>
>> >> There are things you can do to reduce there occurrence as ling as the
>> >> changes do not interfere with your network access for users. For
>> >> instance
>> >> disabling netbios over tcp/ip, disabling the computer browser service,
>> >> and
>> >> configuring the security option for "additional restrictions for
>> >> anonymous
>> >> access" to be " no access without explicit anonymous permissions". If
>> >> you
>> >> disable netbios over tcp/ip on a computer it will no longer show in or
>> >> be
>> >> able to use My Network Places but access to shares can still be done
>> >> via
>> >> fully qualified domain name or possibly even netbios name as long as
>> >> dns
>> >> can
>> >> resolve the non FQDN by appending parent suffix to the request. The
>> >> link
>> >> below explains anonymous access more and the security option to
>> >> restrict
>> >> it
>> >> along with possible consequences of doing such. --- Steve
>> >>
>> >> http://support.microsoft.com/?kbid=246261
>> >>
>> >> "/.dz" </.dz@discussions.microsoft.com> wrote in message
>> >> news:480AE832-9FE3-4740-A265-6F6CA5A898FD@microsoft.com...
>> >> > The security event log on our W2K, SP4 server has hundreds of the
>> >> > above
>> >> > messages in it. There are no associated 'logon' events, just the
>> >> > 'logoff'
>> >> > events.
>> >> >
>> >> > File and Print sharing is enabled on this server.
>> >> >
>> >> > There are several published file shares (all hidden); and there are
>> >> > individuals who are authorized to use those shares. The security
>> >> > log
>> >> > does
>> >> > contain 540/538 'pairs' that reflect the credentials of these known
>> >> > users
>> >> > (user/domain). (These are also 'Logon Type 3') But the number of
>> >> > 538
>> >> > NT
>> >> > AUTHORITY/ANONYMOUS LOGON events absolutely dwarfs the number of
>> >> > "known
>> >> > user"
>> >> > logon/logoff events.
>> >> >
>> >> > The server itself is not a domain controller. It was until recently
>> >> > a
>> >> > member of a NT domain, and now is under AD (I don't know how to
>> >> > state
>> >> > that
>> >> > with any accuracy). 'Known user' logon/logoff events are present
>> >> > for
>> >> > both
>> >> > the 'older' NT domain, and the newer 'AD' whatever).
>> >> >
>> >> > I've scoured newsgroups and the MS web site without any luck
>> >> > whatsoever.
>> >> > Any feedback would be greatly appreciated.
>> >> >
>> >>
>> >>
>> >>
>>
>>
>>
- Previous message: Cristian Martinez Casado: "Re: How do I find what computers a user is logged into?"
- In reply to: /.dz: "Re: Event ID 538 Logon Type 3 NT AUTHORITY/ANONYMOUS LOGON"
- Next in thread: /.dz: "Re: Event ID 538 Logon Type 3 NT AUTHORITY/ANONYMOUS LOGON"
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