We are experiencing multiple (30 or so a day at intervals) logon failure alerts for a particular server, but no user name is listed. Looking at this server, we can find no service account not using the proper credentials, cached credentials or scheduled tasks that are running. We will get 8 or 9 alerts at once, then nothing for an hour or so followed by the same alerts. Really having a hard time running this issue down and fixing it. I've included what logs I could gather from our domain controller and from the reported server below. Just as an FYI, the initial email alert comes from our SolarWinds LEM. Thanks!
INITIAL EMAIL ALERT
logon failure "\" at 2016-09-15 12:49:40.0 from Server1 on DC Server1.DOMAIN.LOCAL
Lockout Reason: unknown user name or bad password.
SECURITY EVENT LOG FROM <DomainController> (EVENT ID 4768)
A Kerberos authentication ticket (TGT) was requested.
Account Information:
Account Name: X509N:<S>CN=Server1WebClient
Supplied Realm Name: DOMAIN.LOCAL
User ID: NULL SID
Service Information:
Service Name: krbtgt/DOMAIN.LOCAL
Service ID: NULL SID
Network Information:
Client Address: ::ffff:<x.x.x.50>
Client Port: 56842
Additional Information:
Ticket Options: 0x40810010
Result Code: 0x6
Ticket Encryption Type: 0xffffffff
Pre-Authentication Type: -
Certificate Information:
Certificate Issuer Name:
Certificate Serial Number:
Certificate Thumbprint:
Certificate information is only provided if a certificate was used for pre-authentication.
Pre-authentication types, ticket options, encryption types and result codes are defined in RFC 4120.
SECURITY EVENT LOG FROM Server1 (EVENT ID 4625)
An account failed to log on.
Subject:
Security ID: SYSTEM
Account Name: Server1$
Account Domain: Domain
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: Server1
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.