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Suspicious Machine Account Replication - DcSync Indicator

Detects suspicious Active Directory Replication Service (ADRS) requests originating from a machine account (SubjectUserName ending in '$') rather than a legitimate Domain Controller. Under normal operation, only…

Description

Detects suspicious Active Directory Replication Service (ADRS) requests originating from a machine account (SubjectUserName ending in '$') rather than a legitimate Domain Controller. Under normal operation, only Domain Controllers initiate replication requests carrying the DS-Replication-Get-Changes-All right. If a threat actor obtains valid machine account credentials — for example by abusing certificate-based authentication (PKINIT) to impersonate a DC after exploiting a CA vulnerability such as CVE-2026-54121 (Certighost), where a temporary machine account is created to request a DC certificate and then used to perform DCSync — they can dump all domain credential material including the krbtgt hash.

Detection logic

Detection requirements

Platform
Windows

The rule states no platform. This is derived from the ATT&CK technique it maps to.

Log source product
windows
Log source service
security

Known benign triggers

  • Valid DC Sync that is not covered by the filters; please report

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