Description

NTLM authentication failed because the account was a member of the Protected User group.

Message #

NTLM authentication failed because the account was a member of the Protected User group.

Account Name: %1
Device Name: %2
Error Code: %3

Fields #

Description

NTLM authentication failed because access control restrictions are required.

Message #

NTLM authentication failed because access control restrictions are required.

Account Name: %1
Device Name: %2
Error Code: %3

Authentication Policy Information:
	Silo Name: %4
	PolicyName: %5

Fields #

Description

NTLM authentication succeded, but it will fail when Authentication Policy is enforced because access control restrictions are required.

Message #

NTLM authentication succeded, but it will fail when Authentication Policy is enforced because access control restrictions are required.

Account Name: %1
Device Name: %2
Error Code: %3

Authentication Policy Information:
	Silo Name: %4
	PolicyName: %5

Fields #

Description

NTLM client blocked: Outgoing NTLM authentication traffic to remote servers that is blocked.

Message #

NTLM client blocked: Outgoing NTLM authentication traffic to remote servers that is blocked.
Target server: %1
Supplied user: %2
Supplied domain: %3
PID of client process: %4
Name of client process: %5
LUID of client process: %6
User identity of client process: %7
Domain name of user identity of client process: %8
Mechanism OID: %9

NTLM authentication requests from this computer are blocked.

If you want to allow this computer to use NTLM authentication, set the security policy Network Security: Restrict NTLM: Outgoing NTLM traffic to remote servers to Allow all.

If you want only the target server %1 to accept NTLM authentication requests from this computer, set the security policy Network Security: Restrict NTLM: Outgoing NTLM traffic to remote servers to Deny all and then set the security policy Network Security: Restrict NTLM: Add remote server exceptions and list the target server %1 as an exception to use NTLM authentication.

Fields #

Example Event #

{
  "system": {
    "provider": "Microsoft-Windows-NTLM",
    "guid": "ac43300d-5fcc-4800-8e99-1bd3f85f0320",
    "event_source_name": "",
    "event_id": 4001,
    "version": 0,
    "level": 3,
    "task": 1,
    "opcode": 0,
    "keywords": 9223372036854775808,
    "time_created": "2026-05-03T21:03:06.9528515+00:00",
    "event_record_id": 32,
    "correlation": {
      "ActivityID": "64478093-d4f9-0001-1c81-4764f9d4dc01",
      "RelatedActivityID": ""
    },
    "execution": {
      "process_id": 976,
      "thread_id": 1364
    },
    "channel": "Microsoft-Windows-NTLM/Operational",
    "computer": "DESKTOP-K7Q9MS2",
    "security": {
      "user_id": "S-1-5-18"
    }
  },
  "event_data": {
    "TargetName": "cifs/127.0.0.1",
    "UserName": "bogus",
    "DomainName": "BOGUS",
    "CallerPID": "4",
    "ProcessName": "",
    "ClientLUID": "0x4641e93",
    "ClientUserName": "localuser",
    "ClientDomainName": "DESKTOP-K7Q9MS2",
    "MechanismOID": "(NULL)"
  },
  "message": "NTLM client blocked: Outgoing NTLM authentication traffic to remote servers that is blocked.\r\nTarget server: cifs/127.0.0.1\r\nSupplied user: bogus\r\nSupplied domain: BOGUS\r\nPID of client process: 4\r\nName of client process: \r\nLUID of client process: 0x4641E93\r\nUser identity of client process: localuser\r\nDomain name of user identity of client process: DESKTOP-K7Q9MS2\r\nMechanism OID: (NULL)\r\n\r\nNTLM authentication requests from this computer are blocked.\r\n\r\nIf you want to allow this computer to use NTLM authentication, set the security policy Network Security: Restrict NTLM: Outgoing NTLM traffic to remote servers to Allow all.\r\n\r\nIf you want only the target server cifs/127.0.0.1 to accept NTLM authentication requests from this computer, set the security policy Network Security: Restrict NTLM: Outgoing NTLM traffic to remote servers to Deny all and then set the security policy Network Security: Restrict NTLM: Add remote server exceptions and list the target server cifs/127.0.0.1 as an exception to use NTLM authentication."
}

Description

NTLM server blocked: Incoming NTLM traffic to servers that is blocked.

Message #

NTLM server blocked: Incoming NTLM traffic to servers that is blocked
Calling process PID: %1
Calling process name: %2
Calling process LUID: %3
Calling process user identity: %4
Calling process domain identity: %5
Mechanism OID: %6

NTLM authentication requests to this server have been blocked.

If you want this server to allow NTLM authentication, set the security policy Network Security: Restrict NTLM: Incoming NTLM Traffic to Allow all.

Fields #

Description

NTLM server blocked in the domain: NTLM authentication in this domain that is blocked.

Message #

NTLM server blocked in the domain: NTLM authentication in this domain that is blocked
User: %1
Domain: %2
Workstation: %3
PID: %4
Process: %5
Logon type: %6
InProc: %7
Mechanism: %8

NTLM authentication within the domain %2 is blocked.

If you want to allow NTLM authentication requests in the domain %1, set the security policy Network Security: Restrict NTLM: NTLM authentication in this domain to Disabled.

If you want to allow NTLM authentication requests only to specific servers in the domain %1, set the security policy Network Security: Restrict NTLM: NTLM authentication in this domain to Deny for domain servers or Deny domain accounts to domain servers, and then set the security policy Network Security: Restrict NTLM: Add server exceptions in this domain to define a list of servers in this domain as an exception to use NTLM authentication.

Fields #

Description

NTLM Minimum Client Security Block.

Message #

NTLM Minimum Client Security Block:
Calling process PID: %1
Calling Process Name: %2
Negotiated Security Flags: %3
Minimum Security Flags: %4

Fields #

Description

NTLM Minimum Server Security Block.

Message #

NTLM Minimum Server Security Block:
Calling process PID: %1
Calling Process Name: %2
Negotiated Security Flags: %3
Minimum Security Flags: %4

Fields #

Description

NTLM client used the domain password. The attempt to use the DC-generated NTLM secret failed, and fallback to the domain password succeeded.

Message #

NTLM client used the domain password. The attempt to use the DC-generated NTLM secret failed, and fallback to the domain password succeeded.
Account Name: %1
Device Name: %2

Fields #

Description

Attempt to use NTLMv1 failed.

Message #

Attempt to use NTLMv1 failed.

Target server: %1
Supplied user: %2
Supplied domain: %3
PID of client process: %4
Name of client process: %5
LUID of client process: %6
User identity of client process: %7
Domain name of user identity of client process: %8
Mechanism OID: %9

This device does not support NTLMv1. For more information, see https://go.microsoft.com/fwlink/?linkid=856826.

Fields #

Description

Attempt to get credential key by call package blocked by Credential Guard.

Message #

Attempt to get credential key by call package blocked by Credential Guard.

Calling Process Name: %1
Service Host Tag: %2

Fields #

Example Event #

{
  "system": {
    "provider": "Microsoft-Windows-NTLM",
    "guid": "AC43300D-5FCC-4800-8E99-1BD3F85F0320",
    "event_source_name": "",
    "event_id": 4014,
    "version": 0,
    "level": 2,
    "task": 0,
    "opcode": 0,
    "keywords": 9223372036854775808,
    "time_created": "2026-03-12T01:53:29.127433+00:00",
    "event_record_id": 1103,
    "correlation": {
      "ActivityID": "EFDC13CA-B670-4786-969E-784D6C91B8C8"
    },
    "execution": {
      "process_id": 720,
      "thread_id": 6076
    },
    "channel": "Microsoft-Windows-NTLM/Operational",
    "computer": "LAB-WIN11",
    "security": {
      "user_id": "S-1-5-18"
    }
  },
  "event_data": {
    "ImageName": "svchost",
    "SvcHostTag": ""
  },
  "message": ""
}

Description

NTLM client blocked: Outgoing NTLM authentication traffic to remote servers that is blocked.

Message #

NTLM client blocked: Outgoing NTLM authentication traffic to remote servers that is blocked.
Target server: %1
Supplied user: %2
Supplied domain: %3
PID of client process: %4
Name of client process: %5
LUID of client process: %6
User identity of client process: %7
Domain name of user identity of client process: %8
Mechanism OID: %9

An application on this computer attempted NTLM for authentication but the application explicitly blocks NTLM usage. Using an IP address or local user credentials from a remote computer may lead to an NTLM authentication attempt. This event does not mean that NTLM is blocked for all authentication attempts from this computer.

Fields #

Description

This machine attempted to authenticate to a remote resource via NTLM.

Message #

This machine attempted to authenticate to a remote resource via NTLM.

Process Information:
	Process Name: %1
	Process PID: %2

Client Information:
	Username: %3
	Domain: %4
	Hostname: %5 
	Sign-On Type: %6

Target Information:
	Target Machine: %7
	Target Domain: %8
	Target Resource: %9
	Target IP: %10
	Target Network Name: %11

NTLM Usage:
	Reason ID: %12
	Reason: %13

NTLM Security:
	Negotiated Flags: %14
	NTLM Version: %15
	Session Key Status: %16
	Channel Binding: %17
	Service Binding: %18
	MIC Status: %19
	AvFlags: %20
	AvFlags String: %21

For more information, see aka.ms/ntlmlogandblock

Fields #

Description

This machine attempted to authenticate to a remote resource via NTLM.

Message #

This machine attempted to authenticate to a remote resource via NTLM.

Process Information:
	Process Name: %1
	Process PID: %2

Client Information:
	Username: %3
	Domain: %4
	Hostname: %5 
	Sign-On Type: %6

Target Information:
	Target Machine: %7
	Target Domain: %8
	Target Resource: %9
	Target IP: %10
	Target Network Name: %11

NTLM Usage:
	Reason ID: %12
	Reason: %13

NTLM Security:
	Negotiated Flags: %14
	NTLM Version: %15
	Session Key Status: %16
	Channel Binding: %17
	Service Binding: %18
	MIC Status: %19
	AvFlags: %20
	AvFlags String: %21

For more information, see aka.ms/ntlmlogandblock

Fields #

Description

A remote client is using NTLM to authenticate to this workstation.

Message #

A remote client is using NTLM to authenticate to this workstation.

Process Information:
	Process Name: %1
	Process PID: %2

Remote Client Information:
	Username: %3
	Domain: %4
	Client Machine: %5
	Client IP: %6
	Client Network Name: %7

NTLM Security:
	Negotiated Flags: %8
	NTLM Version: %9
	Session Key Status: %10
	Channel Binding: %11
	Service Binding: %12
	Target Machine: %13
	Target Domain: %14
	MIC Status: %15
	AvlFlags: %16
	AvlFlags String: %17

Status: %18
Status Message: %19

For more information, see aka.ms/ntlmlogandblock

Fields #

Description

A remote client is using NTLM to authenticate to this workstation.

Message #

A remote client is using NTLM to authenticate to this workstation.

Process Information:
	Process Name: %1
	Process PID: %2

Remote Client Information:
	Username: %3
	Domain: %4
	Client Machine: %5
	Client IP: %6
	Client Network Name: %7

NTLM Security:
	Negotiated Flags: %8
	NTLM Version: %9
	Session Key Status: %10
	Channel Binding: %11
	Service Binding: %12
	Target Machine: %13
	Target Domain: %14
	MIC Status: %15
	AvlFlags: %16
	AvlFlags String: %17

Status: %18
Status Message: %19

For more information, see aka.ms/ntlmlogandblock

Fields #

Description

Auditing an attempt to use NTLMv1-derived credentials for Single Sign-On.

Message #

Auditing an attempt to use NTLMv1-derived credentials for Single Sign-On. 

Target server: %1
Supplied user: %2
Supplied domain: %3
PID of client process: %4
Name of client process: %5
LUID of client process: %6
User identity of client process: %7
Domain name of user identity of client process: %8
Mechanism OID: %9

For more information, see https://go.microsoft.com/fwlink/?linkid=2321802.

Fields #

Description

An attempt to use NTLMv1-derived credentials for Single Sign-On was blocked due to policy.

Message #

An attempt to use NTLMv1-derived credentials for Single Sign-On was blocked due to policy.

Target server: %1
Supplied user: %2
Supplied domain: %3
PID of client process: %4
Name of client process: %5
LUID of client process: %6
User identity of client process: %7
Domain name of user identity of client process: %8
Mechanism OID: %9

For more information, see https://go.microsoft.com/fwlink/?linkid=2321802.

Fields #

Description

NTLM client blocked audit: Audit outgoing NTLM authentication traffic that would be blocked.

Message #

NTLM client blocked audit: Audit outgoing NTLM authentication traffic that would be blocked.
Target server: %1
Supplied user: %2
Supplied domain: %3
PID of client process: %4
Name of client process: %5
LUID of client process: %6
User identity of client process: %7
Domain name of user identity of client process: %8
Mechanism OID: %9

Audit the NTLM authentication requests from this computer that would be blocked by the target server %1 if the security policy Network Security: Restrict NTLM: Outgoing NTLM traffic to remote servers is set to Deny all.

If you want all servers to accept NTLM authentication requests from this computer, set the security policy Network Security: Restrict NTLM: Outgoing NTLM traffic to remote servers to Allow all.

If you want only the target server %1 to accept NTLM authentication requests from this computer, set the security policy Network Security: Restrict NTLM: Outgoing NTLM traffic to remote servers to Deny all, and then set the security policy Network Security: Restrict NTLM: Add remote server exceptions and list the target server %1 as an exception to use NTLM authentication.

Fields #

References #

• Microsoft Learn https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2008-R2-and-2008/jj865682(v=ws.10)

Description

NTLM server blocked audit: Audit Incoming NTLM Traffic that would be blocked.

Message #

NTLM server blocked audit: Audit Incoming NTLM Traffic that would be blocked
Calling process PID: %1
Calling process name: %2
Calling process LUID: %3
Calling process user identity: %4
Calling process domain identity: %5
Mechanism OID: %6

Audit NTLM authentication requests to this server that would be blocked if the security policy Network Security: Restrict NTLM: Incoming NTLM Traffic is set to Deny all accounts or Deny all domain accounts.

If you want this server to allow NTLM authentication, set the security policy Network Security: Restrict NTLM: Incoming NTLM Traffic to Allow all.

Fields #

Example Event #

{
  "system": {
    "provider": "Microsoft-Windows-NTLM",
    "guid": "AC43300D-5FCC-4800-8E99-1BD3F85F0320",
    "event_source_name": "",
    "event_id": 8002,
    "version": 0,
    "level": 4,
    "task": 2,
    "opcode": 0,
    "keywords": 9223372036854775808,
    "time_created": "2026-03-12T02:56:00.824258+00:00",
    "event_record_id": 1104,
    "correlation": {
      "ActivityID": "CC8E79E3-F5C5-4F46-89CF-44829F945FA1"
    },
    "execution": {
      "process_id": 720,
      "thread_id": 12064
    },
    "channel": "Microsoft-Windows-NTLM/Operational",
    "computer": "LAB-WIN11",
    "security": {
      "user_id": "S-1-5-18"
    }
  },
  "event_data": {
    "CallerPID": 720,
    "ProcessName": "C:\\Windows\\System32\\lsass.exe",
    "ClientLUID": "0x3e4",
    "ClientUserName": "LAB-WIN11$",
    "ClientDomainName": "WORKGROUP",
    "MechanismOID": "(NULL)"
  },
  "message": ""
}

References #

• Microsoft Learn https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2008-R2-and-2008/jj865682(v=ws.10)

Description

NTLM server blocked in the domain audit: Audit NTLM authentication in this domain.

Message #

NTLM server blocked in the domain audit: Audit NTLM authentication in this domain
User: %1
Domain: %2
Workstation: %3
PID: %4
Process: %5
Logon type: %6
InProc: %7
Mechanism: %8

Audit NTLM authentication requests within this domain that would be blocked if the security policy Network Security: Restrict NTLM: NTLM authentication in this domain is set to Deny for domain servers or Deny domain accounts to domain servers.

If you want to allow NTLM authentication requests in the domain %1, set the security policy Network Security: Restrict NTLM: NTLM authentication in this domain to Disabled.

If you want to allow NTLM authentication requests to specific servers in the domain %1, set the security policy Network Security: Restrict NTLM: NTLM authentication in this domain to Deny for domain servers or Deny domain accounts to domain servers, and then set the security policy Network Security: Restrict NTLM: Add server exceptions in this domain to define a list of servers in this domain to use NTLM authentication.

Fields #

Example Event #

{
  "system": {
    "provider": "Microsoft-Windows-NTLM",
    "guid": "AC43300D-5FCC-4800-8E99-1BD3F85F0320",
    "event_source_name": "",
    "event_id": 8003,
    "version": 0,
    "level": 4,
    "task": 2,
    "opcode": 0,
    "keywords": 9223372036854775808,
    "time_created": "2026-03-09T00:55:20.842728+00:00",
    "event_record_id": 957,
    "correlation": {
      "ActivityID": "4F958266-269A-4D65-B9BD-F5FA499B7442"
    },
    "execution": {
      "process_id": 764,
      "thread_id": 3132
    },
    "channel": "Microsoft-Windows-NTLM/Operational",
    "computer": "LAB-WIN11.ludus.domain",
    "security": {
      "user_id": "S-1-5-18"
    }
  },
  "event_data": {
    "UserName": "domainuser",
    "DomainName": "LUDUS",
    "Workstation": "(NULL)",
    "CallerPID": 764,
    "ProcessName": "C:\\Windows\\System32\\lsass.exe",
    "LogonType": 3,
    "InProc": true,
    "MechanismOID": "(NULL)"
  },
  "message": ""
}

Community Notes #

Appearing prior to 4624/4776 may indicate unsuccessful coercion probes.

References #

• Microsoft Learn https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2008-R2-and-2008/jj865682(v=ws.10)