Detect DCSync in Microsoft Sentinel
Adversaries abuse the Windows Directory Replication Service (DRSUAPI) API to simulate replication from a domain controller and extract password data without direct access to the NTDS.dit file. Members of Administrators, Domain Admins, or Enterprise Admins groups can call IDL_DRSGetNCChanges to pull NTLM hashes and historical hashes for accounts including krbtgt. Mimikatz implements this as 'lsadump::dcsync'. Used by Mimikatz, Cobalt Strike, Earth Lusca, Mustang Panda, Storm-0501, and LAPSUS$. Enables Golden Ticket creation via krbtgt hash extraction.
MITRE ATT&CK
- Tactic
- Credential Access
- Technique
- T1003 OS Credential Dumping
- Sub-technique
- T1003.006 DCSync
- Canonical reference
- https://attack.mitre.org/techniques/T1003/006/
KQL Detection Query
let DCSyncAuditEvents = SecurityEvent
| where TimeGenerated > ago(24h)
| where EventID == 4662
| where ObjectType in~ ("domainDNS", "domain")
// DS-Replication-Get-Changes (1131f6aa) and DS-Replication-Get-Changes-All (1131f6ad)
| where Properties has "1131f6aa-9c07-11d1-f79f-00c04fc2dcd2"
or Properties has "1131f6ad-9c07-11d1-f79f-00c04fc2dcd2"
or AccessMask == "0x100"
// Exclude machine accounts (DCs replicate normally)
| where not(SubjectUserName endswith "$")
// Exclude known sync accounts (e.g., Azure AD Connect)
| project TimeGenerated, Computer, SubjectUserName, SubjectDomainName,
ObjectName, AccessMask, Properties;
let DCSyncTooling = DeviceProcessEvents
| where Timestamp > ago(24h)
| where ProcessCommandLine has_any (
"lsadump::dcsync", "dcsync", "DCSync",
"drsuapi", "GetNCChanges", "IDL_DRSGetNCChanges"
)
| project Timestamp, DeviceName, AccountName, FileName, ProcessCommandLine;
union DCSyncAuditEvents, DCSyncTooling
| sort by TimeGenerated desc, Timestamp descDetects DCSync attacks via two vectors: (1) Security Event ID 4662 showing DS-Replication-Get-Changes access from non-machine accounts on domain controllers (the network-based detection), and (2) process creation events for DCSync tooling like Mimikatz lsadump::dcsync. The EventID 4662 approach is the most reliable as it captures the actual replication request at the DC.
Data Sources
Required Tables
False Positives & Tuning
- Azure AD Connect and other legitimate directory synchronization services that use DRSUAPI (configure an explicit exclusion for the sync account)
- Active Directory replication between domain controllers — machine accounts (ending in $) are excluded but verify the exclusion is complete
- Privileged Identity Management (PIM) tooling that reads directory data via replication APIs
- Directory Services administrative tools run by authorized AD administrators during maintenance
Other platforms for T1003.006
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1DCSync via Mimikatz lsadump::dcsync (krbtgt)
Expected signal: Security EventID 4662 on DC: DS-Replication-Get-Changes and DS-Replication-Get-Changes-All access from the running user's account. Sysmon EventID 1 on workstation: process creation for mimikatz.exe with lsadump::dcsync in CommandLine. Network traffic on DRSUAPI RPC ports from workstation to DC.
- Test 2DCSync via Impacket secretsdump (Remote)
Expected signal: Security EventID 4662 on DC with DS-Replication-Get-Changes-All access from the provided account. Network connection from attacker IP to DC on port 445 and DRSUAPI RPC ports. SMB authentication events (EventID 4624) on DC from attacker IP.
- Test 3Check Account for Replication Rights (Reconnaissance)
Expected signal: PowerShell ScriptBlock Log EventID 4104 with Get-ADDomain and Get-Acl commands. Security EventID 4662 for domain object read access. Network connection to DC for LDAP query.
References (6)
- https://attack.mitre.org/techniques/T1003/006/
- https://adsecurity.org/?p=1729
- https://msdn.microsoft.com/library/cc228086.aspx
- https://github.com/gentilkiwi/mimikatz/wiki/module-~-lsadump
- https://blog.harmj0y.net/redteaming/mimikatz-and-dcsync-and-extrasids-oh-my/
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1003.006/T1003.006.md
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