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PublishedJune 8, 2026 at 03:29 PM
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SKILL.md · 100 lines · 3.3 KB
name: hunting-for-dcsync-attacks description: Detect DCSync attacks by analyzing Windows Event ID 4662 for unauthorized DS-Replication-Get-Changes requests from non-domain-controller accounts. domain: cybersecurity subdomain: threat-hunting tags:
- threat-hunting
- dcsync
- active-directory
- credential-access
- t1003.006
- mimikatz
- windows
- dfir
version: '1.0' author: mahipal license: Apache-2.0 d3fend_techniques:
- Application Protocol Command Analysis
- Network Isolation
- Network Traffic Analysis
- Client-server Payload Profiling
- Platform Monitoring
nist_csf:
- DE.CM-01
- DE.AE-02
- DE.AE-07
- ID.RA-05
mitre_attack:
- T1046
- T1057
- T1082
- T1083
- T1003
Hunting for DCSync Attacks
When to Use
- When hunting for DCSync credential theft (MITRE ATT&CK T1003.006)
- After detecting Mimikatz or similar tools in the environment
- During incident response involving Active Directory compromise
- When monitoring for unauthorized domain replication requests
- During purple team exercises testing AD attack detection
Prerequisites
- Windows Security Event Log forwarding enabled (Event ID 4662)
- Audit Directory Service Access enabled via Group Policy
- Domain Computers SACL configured on Domain Object for machine account detection
- SIEM with Windows event data ingested (Splunk, Elastic, Sentinel)
- Knowledge of legitimate domain controller accounts and replication partners
Workflow
- Enable Auditing: Ensure Audit Directory Service Access is enabled on domain controllers.
- Collect Events: Gather Windows Event ID 4662 with AccessMask 0x100 (Control Access).
- Filter Replication GUIDs: Search for DS-Replication-Get-Changes and DS-Replication-Get-Changes-All.
- Identify Non-DC Sources: Flag events where SubjectUserName is not a domain controller machine account.
- Correlate with Network: Cross-reference source IPs against known DC addresses.
- Validate Findings: Exclude legitimate replication tools (Azure AD Connect, SCCM).
- Respond: Disable compromised accounts, reset krbtgt, investigate lateral movement.
Key Concepts
| Concept | Description | |
|---|---|---|
| DCSync | Technique abusing AD replication protocol to extract password hashes | |
| Event ID 4662 | Directory Service Access audit event | |
| DS-Replication-Get-Changes | GUID 1131f6aa-9c07-11d1-f79f-00c04fc2dcd2 | |
| DS-Replication-Get-Changes-All | GUID 1131f6ad-9c07-11d1-f79f-00c04fc2dcd2 | |
| AccessMask 0x100 | Control Access right indicating extended rights verification | |
| T1003.006 | OS Credential Dumping: DCSync |
Tools & Systems
| Tool | Purpose | |
|---|---|---|
| Windows Event Viewer | Direct event log analysis | |
| Splunk | SIEM correlation of Event 4662 | |
| Elastic Security | Detection rules for DCSync patterns | |
| Mimikatz lsadump::dcsync | Attack tool used to perform DCSync | |
| Impacket secretsdump.py | Python-based DCSync implementation | |
| BloodHound | Identify accounts with replication rights |
Output Format
Hunt ID: TH-DCSYNC-[DATE]-[SEQ]Technique: T1003.006Domain Controller: [DC hostname]Subject Account: [Account performing replication]Source IP: [Non-DC IP address]GUID Accessed: [Replication GUID]Risk Level: [Critical/High/Medium/Low]Recommended Action: [Disable account, reset krbtgt, investigate]