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Features

Windows Event ID 4769 - A Kerberos service ticket was requested

Introduction

Windows event ID 4769 is generated every time the Key Distribution Center (KDC) receives a Kerberos Ticket Granting Service (TGS) ticket request.

Kerberos-authentication-protocol.
Figure 1. Kerberos authentication protocol

After the client successfully receives a ticket-granting ticket (TGT) from the KDC, it stores that TGT and sends it to the TGS with the Service Principal Name (SPN) of the resource the client wants to access. TGTs are valid for a certain period of time.

Event ID 4769 (S) — A Kerberos Ticket Granting Service (TGS) was successfully requested

The KDC verifies the TGT of the user before the TGS sends a valid session key for the service to the client. Event ID 4769 is recorded with the Result Code equal to “0x0” if the service ticket and the session key were granted.

Event ID 4769 (F) — A Kerberos Ticket Granting Service (TGS) request failed

If the TGS issue fails, the same event ID 4769 is logged but with the Result Code not equal tostrong> “0x0”. (View all result codes.)

Event ID 4768 is generated every time the KDC attempts to validate the credentials.

Event ID 4776 indicates an authentication attempt using NTLM authentication.

Figure 1. Event ID 4769 — General tab under Event Properties.

Event ID 4769 — General tab under Event Properties.

Figure 2. Event ID 4769 — Details tab under Event Properties.

Event ID 4769 — Details tab under Event Properties.

Description of the event fields.

Account Name: The User Principal Name (UPN) of the account that requested the service ticket.

Note:
The computer account name ends with a $ in a UPN. The Account Name field typically has the following format: user_account_name@FULL\_DOMAIN\_NAME.

User account example: mark@ADAP.WORKSHOP.COM
Computer account example: WIN12R2$@ADAP.WORKSHOP.COM

Account Domain: The name of the Kerberos Realm that the Account Name belongs to.

Logon GUID: A global unique identifier (GUID) is a 128-bit integer number used to identify resources, activities, or instances. The Logon GUID can help you correlate event ID 4769 with other events that can contain the same Logon GUID. These events include event IDs 4624, 4648(S), and 4964(S).

Service Name: The name of the service in the Kerberos Realm for which the TGS ticket was requested.

Service ID: The SID of the service account in the Kerberos Realm for which the TGS ticket was requested.

Client Address: The IP address of the computer from which the TGS request was received.

Client Port: The source port number of the client networdok (TGS request) connection. The Client Port is “0” for local (localhost) requests.

Ticket Options: A set of different ticket flags in hexadecimal format.

The most common values include:
0x40810010 — Forwardable, Renewable, Canonicalize, Renewable-ok
0x40810000 — Forwardable, Renewable, Canonicalize
0x60810010 — Forwardable, Forwarded, Renewable, Canonicalize, Renewable-ok

Ticket Encryption Type: The cryptographic suite that was used to encrypt the issued TGS.

Type Type Name Description
0x1 DES-CBC-CRC Disabled by default for Windows 7 or later and Windows Server 2008 R2 or later.
0x3 DES-CBC-MD5 Disabled by default for Windows 7 or later and Windows Server 2008 R2 or later.
0x11 AES128-CTS-HMAC-SHA1-96 Supported for Windows Server 2008 or later and Windows Vista or later.
0x12 AES256-CTS-HMAC-SHA1-96 Supported for Windows Server 2008 or later and Windows Vista or later.
0x17 RC4-HMAC Default suite for operating systems before Windows Server 2008 and Windows Vista.
0x18 RC4-HMAC-EXP Default suite for operating systems before Windows Server 2008 and Windows Vista.
0xFFFFFFFF or 0xffffffff - This type shows in Audit Failure events.

Failure Code: This is a set of different failure codes displayed in hexadecimal format. The result codes are listed in the following table:

See RFC1510 for more details.

Code Code name Description Possible causes
0x0 KDC_ERR_NONE No error No errors were found.
0x1 KDC_ERR_NAME_EXP Client's entry in KDC database has expired No information.
0x2 KDC_ERR_SERVICE_EXP Server's entry in KDC database has expired No information.
0x3 KDC_ERR_BAD_PVNO Requested Kerberos version number not supported No information.
0x4 KDC_ERR_C_OLD_MAST_KVNO Client's key encrypted in old master key No information.
0x5 KDC_ERR_S_OLD_MAST_KVNO Server's key encrypted in old master key No information.
0x6 KDC_ERR_C_PRINCIPAL_UNKNOWN Client not found in Kerberos database The username doesn’t exist.
0x7 KDC_ERR_S_PRINCIPAL_UNKNOWN Server not found in Kerberos database The domain controller can’t find the server’s name in Active Directory.
0x8 KDC_ERR_PRINCIPAL_NOT_UNIQUE Multiple principal entries in KDC database

Duplicate principal names exist.

Unique principal names are crucial for ensuring mutual authentication; duplicate principal names are strictly forbidden, even across multiple realms. Without unique principal names, the client has no way of ensuring that the server it's communicating with is the correct one

0x9 KDC_ERR_NULL_KEY The client or server has a null key (master key) No master key was found for the client or server. This usually means that the administrator should reset the password on the account.
0xA KDC_ERR_CANNOT_POSTDATE Ticket (TGT) not eligible for postdating A client has requested postdating of a Kerberos ticket (setting the ticket’s start time to a future date/time), or there is a time difference between the client and the KDC.
0xB KDC_ERR_NEVER_VALID Requested start time is later than the end time There is a time difference between the KDC and the client.
0xC KDC_ERR_POLICY Requested start time is later than the end time There are logon restrictions on the user’s account, like a workstation restriction, smart card authentication requirement, or logon time restriction.
0xD KDC_ERR_BADOPTION KDC cannot accommodate requested option The TGT is about to expire, or the client is attempting to delegate credentials to an SPN that’s not in its allowed-to-delegate-to list.
0xE KDC_ERR_ETYPE_NOTSUPP KDC has no support for encryption type The KDC or client received a packet that it can’t decrypt.
0xF KDC_ERR_SUMTYPE_NOSUPP KDC has no support for checksum type The KDC, server, or client received a packet that it doesn’t have an appropriate encryption key for, so it can’t decrypt the ticket.
0x10 KDC_ERR_PADATA_TYPE_NOSUPP KDC has no support for PADATA type (pre-authentication data)
  • Smart card logon is being attempted and the proper certificate can’t be located. This can happen because the wrong certificate authority (CA) is being queried or the proper CA can’t be contacted.
  • A domain controller doesn’t have a certificate installed for smart cards (Domain Controller or Domain Controller Authentication templates).

This error code can’t occur in event 4768, but it can occur in event 4771.

0x11 KDC_ERR_TRTYPE_NO_SUPP KDC has no support for transited type No information.
0x12 KDC_ERR_CLIENT_REVOKED Client’s credentials have been revoked There may be explicit restrictions on the account; the account could also be disabled, expired, or locked out.
0x13 KDC_ERR_SERVICE_REVOKED Credentials for server have been revoked No information.
0x14 KDC_ERR_TGT_REVOKED TGT has been revoked

Since the remote KDC may change its PKCROSS key while there are PKCROSS tickets still active, it should cache the old PKCROSS keys until the last issued PKCROSS ticket expires. Otherwise, the remote KDC will respond to a client with this error code.

See RFC1510 for more details.

0x15 KDC_ERR_CLIENT_NOTYET Client not yet valid—try again later No information.
0x16 KDC_ERR_SERVICE_NOTYET Server not yet valid—try again later No information.
0x17 KDC_ERR_KEY_EXPIRED Password has expired—change password to reset

The user’s password has expired.

This error code can’t occur in event 4768, but it does occur in event 4771.

0x18 KDC_ERR_PREAUTH_FAILED Pre-authentication information was invalid

The wrong password was provided.

This error code can’t occur in event 4768, but it does occur in event 4771.

0x19 KDC_ERR_PREAUTH_REQUIRED Additional pre-authentication required

Often occurs in UNIX interoperability scenarios. MIT-Kerberos clients do not request pre-authentication when they send a KRB_AS_REQ message. If pre-authentication is required (the default setting), Windows systems will send this error.

Most MIT-Kerberos clients will respond to this error by giving preauthentication, in which case the error can be ignored

0x1A KDC_ERR_SERVER_NOMATCH KDC does not know about the requested server No information.
0x1B KDC_ERR_SVC_UNAVAILABLE KDC is unavailable No information.
0x1F KRB_AP_ERR_BAD_INTEGRITY Integrity check on decrypted field failed

The authenticator was encrypted with something other than the session key, so the client can’t decrypt the resulting message.

The modification of the message could be the result of an attack or network noise.

0x20 KRB_AP_ERR_TKT_EXPIRED The ticket has expired

The smaller the value for the Kerberos policy setting Maximum lifetime for user ticket, the more likely it is that this error will occur.

Because ticket renewal is automatic, you shouldn’t have to do anything if you get this message.

0x21 KRB_AP_ERR_TKT_NYV The ticket is not yet valid

The clocks on the KDC and the client aren’t synchronized.

If cross-realm Kerberos authentication is being attempted, then you should verify time synchronization between the KDC in the target realm and the KDC in the client realm.

0x22 KRB_AP_ERR_REPEAT The request is a replay A specific authenticator showed up twice; in other words, the KDC detected that this session ticket duplicates one that it has already received.
0x23 KRB_AP_ERR_NOT_US The ticket is not for us The server has received a ticket that was meant for a different realm.
0x24 KRB_AP_ERR_BADMATCH The ticket and authenticator do not match
  • The KRB_TGS_REQ is being sent to the wrong KDC.
  • There was an account mismatch during protocol transition.
0x25 KRB_AP_ERR_SKEW The clock skew is too great A client computer sent a timestamp whose value differs from that of the server’s timestamp by more than the Maximum tolerance for computer clock synchronization setting in the Kerberos policy.
0x26 KRB_AP_ERR_BADADDR Network address in network layer header doesn't match address inside ticket
  • The address of the computer sending the ticket is different from the valid address in the ticket. A possible cause of this could be an IP address change.
  • A ticket was passed through a proxy server or NAT. The client is unaware of the address scheme used by the proxy server, so unless the program caused the client to request a proxy server ticket with the proxy server's source address, the ticket could be invalid.
0x28 KRB_AP_ERR_BADVERSION Protocol version numbers don't match (PVNO) An application checks the KRB_SAFE message to verify that the protocol version and type fields match the current version and KRB_SAFE, respectively. A mismatch generates this error code.
0x28 KRB_AP_ERR_MSG_TYPE Message type is unsupported
  • The target server finds that the message format is wrong. This applies to KRB_AP_REQ, KRB_SAFE, KRB_PRIV, and KRB_CRED messages.
  • The use of UDP protocol is being attempted with user-to-user authentication.
0x29 KRB_AP_ERR_MODIFIED Message stream modified and checksum didn't match
  • The authentication data was encrypted with the wrong key for the intended server.
  • The authentication data was modified in transit by a hardware or software error, or by an attacker.
  • The client sent the authentication data to the wrong server because of incorrect DNS data.
0x2A KRB_AP_ERR_BADORDER Message out of order (possible tampering)

This event generates for KRB_SAFE and KRB_PRIV messages if an incorrect sequence number is included or if a sequence number is expected but not present.

See RFC4120 for more details.

0x2C KRB_AP_ERR_BADKEYVER Specified version of key is not available The server can’t use the key version indicated by the ticket in the KRB_AP_REQ (e.g. it indicates an old key that the server doesn’t have a copy of).
0x2D KRB_AP_ERR_NOKEY Service key not available

The server doesn’t have the right key to decipher the ticket.

Because it's possible for the server to be registered in multiple realms with different keys in each realm, the realm field in the unencrypted portion of the ticket in the KRB_AP_REQ is used to specify which secret key the server should use to decrypt that ticket

0x2E KRB_AP_ERR_MUT_FAIL Mutual authentication failed No information.
0x2F KRB_AP_ERR_BADDIRECTION Incorrect message direction No information.
0x30 KRB_AP_ERR_METHOD Alternative authentication method required According to RFC4120, this error message is obsolete.
0x31 KRB_AP_ERR_BADSEQ Incorrect sequence number in message No information.
0x32 KRB_AP_ERR_INAPP_CKSUM Inappropriate type of checksum in message (checksum may be unsupported) When the KDC receives a KRB_TGS_REQ message, it decrypts it. Afterwards, the user-supplied checksum in the Authenticator must be verified against the contents of the request, and the message must be rejected if the checksums don't match (with an error code of KRB_AP_ERR_MODIFIED) or if the checksum is not collision-proof (with an error code of KRB_AP_ERR_INAPP_CKSUM).
0x33 KRB_AP_PATH_NOT_ACCEPTED Desired path is unreachable No information.
0x34 KRB_ERR_RESPONSE_TOO_BIG Too much data

The size of a ticket is too large to be transmitted reliably via UDP.

In a Windows environment, this message is purely informational. A Windows computer will automatically try TCP if UDP fails.

0x3C KRB_ERR_GENERIC Generic error
  • Group membership has overloaded the Privilege Account Certificate (PAC).
  • Multiple recent password changes haven't been propagated
  • Crypto subsystem error caused by running out of memory.
  • The SPN is too long.
  • The SPN has too many parts
0x3D KRB_ERR_FIELD_TOOLONG Field is too long for this implementation

If a KDC that does not understand how to interpret a set high bit of the length encoding receives a request with the high order bit of the length set, it must return a KRB-ERROR message with the error KRB_ERR_FIELD_TOOLONG, and it must close the TCP stream

Each request (KRB_KDC_REQ) and response (KRB_KDC_REP or KRB_ERROR) sent over the TCP stream is preceded by the length of the request as 4 octets in network byte order. The high bit of the length is reserved for future expansion and must currently be set to zero.

0x3E KDC_ERR_CLIENT_NOT_TRUSTED The client trust failed or is not implemented
  • A user’s smart card certificate has been revoked.
  • The root CA that issued the smart card certificate (in a chain) is not trusted by the domain controller.
0x3F KDC_ERR_KDC_NOT_TRUSTED The KDC server trust failed or could not be verified

The trustedCertifiers field contains a list of CAs trusted by the client, just in case the client doesn’t possess the KDC's public key certificate. If the KDC has no certificate signed by any of the trustedCertifiers, then it returns this error code.

0x40 KDC_ERR_INVALID_SIG The signature is invalid This error is related to PKINIT. If a PKI trust relationship exists, the KDC then verifies the client's signature on AuthPack (TGT request signature). If that fails, the KDC returns this error code.
0x41 KDC_ERR_KEY_TOO_WEAK A higher encryption level is needed If the clientPublicValue field is filled in, indicating that the client wishes to use the Diffie-Hellman key agreement, then the KDC checks to see that the parameters satisfy its policy. If they do not (e.g. the prime size is insufficient for the expected encryption type), then the KDC returns this error code.
0x42 KRB_AP_ERR_USER_TO_USER_REQUIRED User-to-user authorization is required The client doesn't know that a service requires user-to-user authentication, so it requests, receives, and forwards a conventional KRB_AP_REP to the server; the server generates this error code in response.
0x43 KRB_AP_ERR_NO_TGT No TGT was presented or available The service doesn’t have a TGT for user-to-user authentication.
0x44 KDC_ERR_WRONG_REALM Incorrect domain or principal

The client presented a cross-realm TGT to a realm other than the one specified in the TGT.

This error rarely occurs, but it’s typically caused by an incorrectly configured DNS.

Transited Services: This field contains a list of SPNs which were requested if Kerberos delegation was used.

Reasons to monitor event ID 4769:

  • Monitor the Client Address field to track logon attempts that are not from your internal IP range.
  • Monitor event ID 4769 for accounts that have an Account Name that corresponds to high-value accounts, including administrators, built-in local administrators, domain administrators, and service accounts.
  • If you have a list of accounts that are allowed to log on directly to domain controllers (rather than via network logon or Remote Desktop Connection), then monitor when Client Address is equal to “::1” to identify violations and possible malicious intent.
  • Monitor when Result Code is equal to “0x8” (multiple principal entries in KDC database) to detect duplicate SPNs and possible attempts of Kerberoasting.
  • Monitor when Result Code is equal to “0x22” (the request is a replay) to indicate that a specific authenticator showed up twice. It could be a sign of an attack.
  • Monitor any Ticket Encryption Type other than “0x11” and “0x12”. These are the expected values, and they represent AES-family algorithms. Ticket Encryption Type “0x1” or “0x3” means that the DES algorithm was used. DES should not be in use due to its poor security and known vulnerabilities.

The need for an auditing solution:

Auditing solutions like ADAudit Plus offer real-time monitoring, user and entity behavior analytics, and reports; together these features help secure your AD environment.

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Although you can attach a task to the security log and ask Windows to send you an email, you are limited to simply getting an email whenever event ID 4769 is generated. Windows also lacks the ability to apply more granular filters that are required to meet security recommendations

For example, Windows can send you an email every time event ID 4769 is generated, but it won't be able to only notify you when high-value accounts have generated the event ID, or if a Kerberos service ticket request came from an unauthorized endpoint. Getting more specific alerts reduces the chance of missing out on critical notifications hidden amongst a heap of false-positive alerts.

With a tool like ADAudit Plus, not only can you apply granular filters to focus on real threats, you can get notified in real time via SMS, too.

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