Server generating lots of 4625 logon failure event log entries

I am looking at a Windows Server 2012 Essentials that is generating one of these event log entries repeatedly, sometimes multiple times a second, sometimes every 5 minutes. There are over 230,000 of them in the log right now.

I've been googling like a madman but have not been able to find out more information about how to track back what exactly is doing this, it appears to be something on the server itself.

Any advice on how to narrow this down would be greatly appreciated.

Log Name:      Security
Source:        Microsoft-Windows-Security-Auditing
Date:          27/03/2017 12:26:03 PM
Event ID:      4625
Task Category: Logon
Level:         Information
Keywords:      Audit Failure
User:          N/A
Computer:      {NameOfTheServer}.{NameOfTheDomain}.local
Description:
An account failed to log on.

Subject:
      Security ID:            SYSTEM
      Account Name:            {NameOfTheServer}$
      Account Domain:            {NameOfTheDomain}
      Logon ID:            0x3E7

Logon Type:                  3

Account For Which Logon Failed:
      Security ID:            NULL SID
      Account Name:            
      Account Domain:            

Failure Information:
      Failure Reason:            Unknown user name or bad password.
      Status:                  0xC000006D
      Sub Status:            0xC0000064

Process Information:
      Caller Process ID:      0x264
      Caller Process Name:      C:\Windows\System32\lsass.exe

Network Information:
      Workstation Name:      {NameOfTheServer}
      Source Network Address:      -
      Source Port:            -

Detailed Authentication Information:
      Logon Process:            Schannel
      Authentication Package:      Kerberos
      Transited Services:      -
      Package Name (NTLM only):      -
      Key Length:            0

This event is generated when a logon request fails. It is generated on the computer where access was attempted.

The Subject fields indicate the account on the local system which requested the logon. This is most commonly a service such as the Server service, or a local process such as Winlogon.exe or Services.exe.

The Logon Type field indicates the kind of logon that was requested. The most common types are 2 (interactive) and 3 (network).

The Process Information fields indicate which account and process on the system requested the logon.

The Network Information fields indicate where a remote logon request originated. Workstation name is not always available and may be left blank in some cases.

The authentication information fields provide detailed information about this specific logon request.
      - Transited services indicate which intermediate services have participated in this logon request.
      - Package name indicates which sub-protocol was used among the NTLM protocols.
      - Key length indicates the length of the generated session key. This will be 0 if no session key was requested.
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="Microsoft-Windows-Security-Auditing" Guid="{54849625-5478-4994-A5BA-3E3B0328C30D}" />
    <EventID>4625</EventID>
    <Version>0</Version>
    <Level>0</Level>
    <Task>12544</Task>
    <Opcode>0</Opcode>
    <Keywords>0x8010000000000000</Keywords>
    <TimeCreated SystemTime="2017-03-27T02:26:03.902624800Z" />
    <EventRecordID>44567885</EventRecordID>
    <Correlation />
    <Execution ProcessID="612" ThreadID="31404" />
    <Channel>Security</Channel>
    <Computer>{NameOfTheServer}.{NameOfTheDomain}.local</Computer>
    <Security />
  </System>
  <EventData>
    <Data Name="SubjectUserSid">S-1-5-18</Data>
    <Data Name="SubjectUserName">{NameOfTheServer}$</Data>
    <Data Name="SubjectDomainName">{NameOfTheDomain}</Data>
    <Data Name="SubjectLogonId">0x3e7</Data>
    <Data Name="TargetUserSid">S-1-0-0</Data>
    <Data Name="TargetUserName">
    </Data>
    <Data Name="TargetDomainName">
    </Data>
    <Data Name="Status">0xc000006d</Data>
    <Data Name="FailureReason">%%2313</Data>
    <Data Name="SubStatus">0xc0000064</Data>
    <Data Name="LogonType">3</Data>
    <Data Name="LogonProcessName">Schannel</Data>
    <Data Name="AuthenticationPackageName">Kerberos</Data>
    <Data Name="WorkstationName">{NameOfTheServer}</Data>
    <Data Name="TransmittedServices">-</Data>
    <Data Name="LmPackageName">-</Data>
    <Data Name="KeyLength">0</Data>
    <Data Name="ProcessId">0x264</Data>
    <Data Name="ProcessName">C:\Windows\System32\lsass.exe</Data>
    <Data Name="IpAddress">-</Data>
    <Data Name="IpPort">-</Data>
  </EventData>
</Event>
OzoneFriendlyAsked:
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John TsioumprisSoftware & Systems EngineerCommented:
Do you have any accounts lockout (do you have lockout policy) ?
Anyway download Netwrix Account Lockout Examiner to check if you have numerous failed logons....Netwrix will guide you to see all the latest attempts with extra information....common reasons ....forgotten passwords on mobile devices/other devices , viruses (conflicker), external/internal attacks (trying to guess password)
If the above doesn't pay then a good move would be to install NetWork Monitor and let it capture data until couple of these events are written on the event log....then stop it and examine the trace file....normally somewhere lurks the issue...
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Ajit SinghCommented:
This Event is usually caused by a stale hidden credential. Try this from the system giving the error:

From a command prompt run: psexec -i -s -d cmd.exe
From the new cmd window run: rundll32 keymgr.dll,KRShowKeyMgr

Remove any items that appear in the list of Stored User Names and Passwords. Restart the computer.

Refer to below links for more information about issue and solution:

http://serverfault.com/questions/379092/remote-desktop-failed-logon-event-4625-not-logging-ip-address-on-2008-terminal-s/403638#403638

http://serverfault.com/questions/686393/event-4625-audit-failure-null-sid-failed-network-logons

Also get help from this article to track locked out accounts and find the source:
https://www.lepide.com/how-to/identify-the-source-of-account-lockouts-in-active-directory.html

Hope this helps!
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OzoneFriendlyAuthor Commented:
Thanks for the advice experts;

With regards to Netwrix Lockout Examiner - The server doesn't appear to have a lockout policy enabled, and most user accounts show zero bad password count, with a few showing 1 or 2 which sounds like those users just messed up their password once or twice.

There is the guest account which has 518 bad passwords however. Not sure if that tells me anything as the guest username is not showing in the event logs in question. (might be, just not in any I've looked at)

psexec -i -s -d cmd.exe does not work for me, says it's not a valid command. Am I missing something?

rundll32 keymgr.dll,KRShowKeyMgr - This does work from a command prompt and I have removed the credentials in there.

The server fault page 379092 assumes these are RDP login attempts, however there are no corresponding entries in any of the terminal services / remote desktop event logs.

The server fault page 686393 sounds exactly like what I am seeing and I am using that as a bit of a guide, as it doesn't give a specific resolution.  I'm beginning to think this might explain it, at least on one machine.
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Ajit SinghCommented:
Is there any update?
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Ajit SinghCommented:
Answered, no further question from author. Please post back if you need further assistance.
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Windows Server 2012

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