DC Machine Account TGT Request from Non-DC Source IP

SIGMA detection rule by Swachchhanda Shrawan Poudel (Nextron Systems) · Unknown

Detects a Kerberos TGT request (Event 4768) for a known Domain Controller machine account originating from an IP address that is not a known Domain Controller. DC machine accounts should only request TGTs from their own IP. Any TGT request for a DC account from a workstation or non-DC host is anomalous and indicates one of the following: - PKINIT abuse (CVE-2026-54121 / Certighost): attacker authenticating as a DC via a forged certificate from their workstation - Overpass-the-Hash: attacker converting a stolen DC machine account NTLM hash into a Kerberos TGT - Pass-the-Hash (RC4): attacker using the DC machine account hash directly with Kerberos

title: DC Machine Account TGT Request from Non-DC Source IP
id: 9c5d2b84-1f7e-4a3c-d6b8-e04f9a17c523
status: experimental
description: |
    Detects a Kerberos TGT request (Event 4768) for a known Domain Controller machine account
    originating from an IP address that is not a known Domain Controller. DC machine accounts
    should only request TGTs from their own IP. Any TGT request for a DC account from a
    workstation or non-DC host is anomalous and indicates one of the following:

      - PKINIT abuse (CVE-2026-54121 / Certighost): attacker authenticating as a DC via a
        forged certificate from their workstation
      - Overpass-the-Hash: attacker converting a stolen DC machine account NTLM hash into a
        Kerberos TGT
      - Pass-the-Hash (RC4): attacker using the DC machine account hash directly with Kerberos
references:
    - https://github.com/aniqfakhrul/CVE-2026-54121
    - https://gist.github.com/H0j3n/a5ef2609b5f2944ac2390a191a534c26
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2026-07-29
tags:
    - attack.credential-access
    - attack.lateral-movement
    - attack.t1649
    - attack.t1550.003
    - attack.t1558.001
    - cve.2026-54121
logsource:
    product: windows
    service: security
detection:
    selection:
        EventID: 4768
        Status: '0x0'
        TargetUserName|endswith: '$'
        TargetUserName|expand: '%dc_machine_accounts%'
    filter_main_dc_source:
        IpAddress|expand: '%dc_ip_addresses%'
    filter_main_loopback:
        - IpAddress:
              - '127.0.0.1'
              - '::1'
              - '::ffff:127.0.0.1'
              - '-'
        - IpAddress|startswith: 'fe80:'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Unlikely if %dc_machine_accounts% and %dc_ip_addresses% are correctly populated.
level: high

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