What is the source of thousands of 4625 Logon Failure errors with Logon Type 8 (NetworkCleartext)?

Question

I have a Windows Server 2008 R2 system that's showing thousands of 4625 Logon Failure errors with Logon Type 8 (NetworkCleartext) in the Security section of the Windows Logs every single day. There are no IP addresses of the systems trying to gain access listed in the Source Network Address, so the script I built to block IPs that fail too often can't find them.

What services could these login attempts be coming from?

Here is a sample of one of them:

An account failed to log on.

Subject:
    Security ID:        SYSTEM
    Account Name:       server-name$
    Account Domain:     example
    Logon ID:       0x3e7

Logon Type:         8

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

Failure Information:
    Failure Reason:     Unknown user name or bad password.
    Status:         0xc000006d
    Sub Status:     0xc0000064

Process Information:
    Caller Process ID:  0x4d0
    Caller Process Name:    C:\Windows\System32\svchost.exe

Network Information:
    Workstation Name:   system-name
    Source Network Address: -
    Source Port:        -

Detailed Authentication Information:
    Logon Process:      Advapi  
    Authentication Package: MICROSOFT_AUTHENTICATION_PACKAGE_V1_0
    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.

Answer 1

There are multiple login sources that could possibly be generating these errors:

1. FTP logins - check your FTP log to see if login failures are showing up at the same time. This was the source in my case, which took me entirely too long to figure out, and which is why I'm posting this.
2. Logins via Basic Authentication over http or https (simple, but possibly dangerous, way to password-protect a web site)
3. ASP scripts
4. There are likely others of which I'm not aware

Numbers 2 and 3 are mentioned at WindowsSecurity.com:

This logon type indicates a network logon like logon type 3 but where the password was sent over the network in the clear text. Windows server doesn’t allow connection to shared file or printers with clear text authentication. The only situation I’m aware of are logons from within an ASP script using the ADVAPI or when a user logs on to IIS using IIS’s basic authentication mode. In both cases the logon process in the event’s description will list advapi. Basic authentication is only dangerous if it isn’t wrapped inside an SSL session (i.e. https). As far as logons generated by an ASP, script remember that embedding passwords in source code is a bad practice for maintenance purposes as well as the risk that someone malicious will view the source code and thereby gain the password.

Answer 2

I'd run a netstat -a -n | find "1232" to see what ports process ID (PID) 1232 is listening on. That's the PID that's generating these authentication failures. You could sniff traffic incoming on those ports to track down the source.

(I'm having a hard time coming up with services that run in-process w/ svchost.exe and listen for authentication. It almost feels third-party to me...)

Answer 3

The logon type 8 occurs when the password was sent over the network in the clear text. Basic authentication in IIS is most possible cause for this kind of login failure. As for as I know there are five commonly used Microsoft IIS based services with Basic Authentication by end users via either by their Desktop or Mobile device, such are OWA client, MS Exchange ActiveSync, Outlook Anywhere, FTP client and SharePoint server.

When an end-user connect the Basic authentication enabled OWA client from their desktop-pc/mobile device with wrong passwords, the event 4625 with logon type 8 will be logged in Exchange Server which hosts the OWA.

Check this article: http://www.morgantechspace.com/2014/12/Find-Account-Lockout-Source-for-Logon-Type-8.html