DCSync
DCSync [T1003.006]
Information
Introduction
DCSync (T1003.006) is a sub-technique of the Credential Dumping technique within the MITRE ATT&CK framework. This method specifically involves adversaries simulating Domain Controller (DC) replication requests to extract credential hashes and other sensitive information from Active Directory (AD). By leveraging legitimate directory replication services, attackers can obtain critical credentials without directly interacting with the targeted domain controller or installing malicious software on it, significantly reducing the risk of detection.
Deep Dive Into Technique
DCSync leverages the Directory Replication Service Remote Protocol (MS-DRSR), a legitimate Active Directory protocol used by domain controllers to synchronize data. Attackers exploit this protocol by impersonating a domain controller and initiating replication requests, typically targeting sensitive attributes such as password hashes.
Key technical points:
Attackers require specific Active Directory permissions to perform DCSync operations, notably:
Replicating Directory Changes
Replicating Directory Changes All
Replicating Directory Changes in Filtered Set
These permissions are typically granted to domain controllers and certain privileged accounts.
Attackers commonly use tools such as Mimikatz, Impacket's secretsdump.py, or PowerSploit to conduct DCSync attacks.
The attack does not require code execution on domain controllers, thus minimizing forensic artifacts.
DCSync requests are performed remotely, making them harder to detect through traditional endpoint monitoring.
Typical execution steps:
Identify a compromised account with sufficient replication privileges or escalate privileges to obtain such permissions.
Use specialized tools (e.g., Mimikatz with
lsadump::dcsyncmodule) to request replication of sensitive information from a legitimate domain controller.Extract password hashes (NTLM hashes), Kerberos keys, and other sensitive domain credentials.
Utilize extracted credentials in further lateral movement, privilege escalation, or domain compromise activities.
When this Technique is Usually Used
DCSync is commonly employed in the following stages and scenarios of an attack:
Credential Access:
Attackers use this technique to dump credential hashes, enabling further lateral movement and privilege escalation within an Active Directory environment.
Privilege Escalation:
After initial compromise of a domain account, attackers escalate privileges by extracting credentials of higher-privileged accounts (e.g., Domain Admin).
Persistence and Domain Dominance:
Attackers leverage DCSync to maintain persistent access and control over the entire AD infrastructure by continuously harvesting credentials.
Post-Exploitation:
Often used after initial access and internal reconnaissance, enabling attackers to move deeper into sensitive systems without raising alarms associated with direct domain controller access.
How this Technique is Usually Detected
Detecting DCSync attacks requires monitoring and analyzing specific Active Directory and network events:
Event Log Monitoring:
Windows Security Event Logs, particularly event IDs:
4662 (An operation was performed on an object): Monitor for replication requests involving sensitive attributes.
4624 (Successful logon): Identify suspicious logons from non-domain controller endpoints.
Network Traffic Analysis:
Monitor MS-DRSR protocol traffic (TCP port 445, RPC calls over SMB) from unusual sources.
Tools like Zeek, Suricata, or Wireshark can help detect abnormal replication requests.
Behavioral Analytics:
Implement User and Entity Behavior Analytics (UEBA) solutions to identify anomalous replication requests or unusual account behavior.
Endpoint Detection and Response (EDR) Solutions:
Advanced EDR solutions can detect the use of tools such as Mimikatz, PowerSploit, or Impacket scripts.
Indicators of Compromise (IoCs):
Unusual replication requests originating from non-DC endpoints.
Unexpected access to sensitive AD attributes (e.g., password hashes, Kerberos keys).
Unusual usage patterns of privileged accounts with replication privileges.
Why it is Important to Detect This Technique
Early detection and mitigation of DCSync attacks are crucial due to their severe potential impacts:
Credential Theft:
Attackers gain access to sensitive credential hashes, enabling persistent access and lateral movement.
Privilege Escalation:
Compromise of high-privileged accounts (e.g., Domain Admin) can rapidly escalate into full domain takeover.
Persistence and Stealth:
DCSync attacks do not require malware installation or direct domain controller access, making them stealthy and difficult to detect.
Damage to Organizational Security Posture:
Successful DCSync attacks undermine Active Directory security, potentially leading to extensive data breaches, disruption of services, and loss of trust.
Regulatory and Compliance Implications:
Undetected credential compromises can result in regulatory fines, legal actions, and reputational damage.
Examples
Real-world examples of DCSync attacks include:
APT29 (Cozy Bear) Attacks:
Utilized DCSync technique to extract credential hashes from compromised Active Directory domains.
Tools used: Mimikatz, PowerSploit.
Impact: Enabled persistent access, lateral movement, and espionage operations.
Ryuk Ransomware Attacks:
Attackers leveraged DCSync to harvest credentials within targeted organizations, escalating privileges rapidly.
Tools used: Mimikatz, Impacket secretsdump.py.
Impact: Facilitated rapid lateral movement, domain compromise, and deployment of ransomware payloads.
FIN6 Financially Motivated Attacks:
Used DCSync to extract domain administrator hashes, enabling extensive lateral movement across financial institutions.
Tools used: Impacket, Mimikatz.
Impact: Led to significant financial theft, data breaches, and operational disruptions.
NotPetya Malware Incident:
Incorporated credential extraction methods including DCSync to propagate rapidly across compromised networks.
Tools used: Modified Mimikatz modules embedded within malware.
Impact: Massive global disruption, extensive financial damage, and widespread operational outages.
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